Last data update: Nov 04, 2024. (Total: 48056 publications since 2009)
Records 1-19 (of 19 Records) |
Query Trace: Thor S[original query] |
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Antigenic characterization of circulating and emerging SARS-CoV-2 variants in the U.S. Throughout the Delta to Omicron waves
Di H , Pusch EA , Jones J , Kovacs NA , Hassell N , Sheth M , Lynn KS , Keller MW , Wilson MM , Keong LM , Cui D , Park SH , Chau R , Lacek KA , Liddell JD , Kirby MK , Yang G , Johnson M , Thor S , Zanders N , Feng C , Surie D , DeCuir J , Lester SN , Atherton L , Hicks H , Tamin A , Harcourt JL , Coughlin MM , Self WH , Rhoads JP , Gibbs KW , Hager DN , Shapiro NI , Exline MC , Lauring AS , Rambo-Martin B , Paden CR , Kondor RJ , Lee JS , Barnes JR , Thornburg NJ , Zhou B , Wentworth DE , Davis CT . Vaccines (Basel) 2024 12 (5) Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has evolved into numerous lineages with unique spike mutations and caused multiple epidemics domestically and globally. Although COVID-19 vaccines are available, new variants with the capacity for immune evasion continue to emerge. To understand and characterize the evolution of circulating SARS-CoV-2 variants in the U.S., the Centers for Disease Control and Prevention (CDC) initiated the National SARS-CoV-2 Strain Surveillance (NS3) program and has received thousands of SARS-CoV-2 clinical specimens from across the nation as part of a genotype to phenotype characterization process. Focus reduction neutralization with various antisera was used to antigenically characterize 143 SARS-CoV-2 Delta, Mu and Omicron subvariants from selected clinical specimens received between May 2021 and February 2023, representing a total of 59 unique spike protein sequences. BA.4/5 subvariants BU.1, BQ.1.1, CR.1.1, CQ.2 and BA.4/5 + D420N + K444T; BA.2.75 subvariants BM.4.1.1, BA.2.75.2, CV.1; and recombinant Omicron variants XBF, XBB.1, XBB.1.5 showed the greatest escape from neutralizing antibodies when analyzed against post third-dose original monovalent vaccinee sera. Post fourth-dose bivalent vaccinee sera provided better protection against those subvariants, but substantial reductions in neutralization titers were still observed, especially among BA.4/5 subvariants with both an N-terminal domain (NTD) deletion and receptor binding domain (RBD) substitutions K444M + N460K and recombinant Omicron variants. This analysis demonstrated a framework for long-term systematic genotype to antigenic characterization of circulating and emerging SARS-CoV-2 variants in the U.S., which is critical to assessing their potential impact on the effectiveness of current vaccines and antigen recommendations for future updates. |
Swine-to-Ferret Transmission of Antigenically Drifted Contemporary Swine H3N2 Influenza A Virus Is an Indicator of Zoonotic Risk to Humans.
Souza CK , Kimble JB , Anderson TK , Arendsee ZW , Hufnagel DE , Young KM , Gauger PC , Lewis NS , Davis CT , Thor S , Vincent Baker AL . Viruses 2023 15 (2) Human-to-swine transmission of influenza A (H3N2) virus occurs repeatedly and plays a critical role in swine influenza A virus (IAV) evolution and diversity. Human seasonal H3 IAVs were introduced from human-to-swine in the 1990s in the United States and classified as 1990.1 and 1990.4 lineages; the 1990.4 lineage diversified into 1990.4.A-F clades. Additional introductions occurred in the 2010s, establishing the 2010.1 and 2010.2 lineages. Human zoonotic cases with swine IAV, known as variant viruses, have occurred from the 1990.4 and 2010.1 lineages, highlighting a public health concern. If a variant virus is antigenically drifted from current human seasonal vaccine (HuVac) strains, it may be chosen as a candidate virus vaccine (CVV) for pandemic preparedness purposes. We assessed the zoonotic risk of US swine H3N2 strains by performing phylogenetic analyses of recent swine H3 strains to identify the major contemporary circulating genetic clades. Representatives were tested in hemagglutination inhibition assays with ferret post-infection antisera raised against existing CVVs or HuVac viruses. The 1990.1, 1990.4.A, and 1990.4.B.2 clade viruses displayed significant loss in cross-reactivity to CVV and HuVac antisera, and interspecies transmission potential was subsequently investigated in a pig-to-ferret transmission study. Strains from the three lineages were transmitted from pigs to ferrets via respiratory droplets, but there were differential shedding profiles. These data suggest that existing CVVs may offer limited protection against swine H3N2 infection, and that contemporary 1990.4.A viruses represent a specific concern given their widespread circulation among swine in the United States and association with multiple zoonotic cases. |
Interspecies Transmission from Pigs to Ferrets of Antigenically Distinct Swine H1 Influenza A Viruses with Reduced Reactivity to Candidate Vaccine Virus Antisera as Measures of Relative Zoonotic Risk.
Kimble JB , Souza CK , Anderson TK , Arendsee ZW , Hufnagel DE , Young KM , Lewis NS , Davis CT , Thor S , Vincent Baker AL . Viruses 2022 14 (11) During the last decade, endemic swine H1 influenza A viruses (IAV) from six different genetic clades of the hemagglutinin gene caused zoonotic infections in humans. The majority of zoonotic events with swine IAV were restricted to a single case with no subsequent transmission. However, repeated introduction of human-seasonal H1N1, continual reassortment between endemic swine IAV, and subsequent drift in the swine host resulted in highly diverse swine IAV with human-origin genes that may become a risk to the human population. To prepare for the potential of a future swine-origin IAV pandemic in humans, public health laboratories selected candidate vaccine viruses (CVV) for use as vaccine seed strains. To assess the pandemic risk of contemporary US swine H1N1 or H1N2 strains, we quantified the genetic diversity of swine H1 HA genes, and identified representative strains from each circulating clade. We then characterized the representative swine IAV against human seasonal vaccine and CVV strains using ferret antisera in hemagglutination inhibition assays (HI). HI assays revealed that 1A.3.3.2 (pdm09) and 1B.2.1 (delta-2) demonstrated strong cross reactivity to human seasonal vaccines or CVVs. However, swine IAV from three clades that represent more than 50% of the detected swine IAVs in the USA showed significant reduction in cross-reactivity compared to the closest CVV virus: 1A.1.1.3 (alpha-deletion), 1A.3.3.3-clade 3 (gamma), and 1B.2.2.1 (delta-1a). Representative viruses from these three clades were further characterized in a pig-to-ferret transmission model and shown to exhibit variable transmission efficiency. Our data prioritize specific genotypes of swine H1N1 and H1N2 to further investigate in the risk they pose to the human population. |
Pathogenesis and Transmission of Human Seasonal and Swine-origin A(H1) Influenza Viruses in the Ferret Model.
Pulit-Penaloza JA , Brock N , Jones J , Belser JA , Jang Y , Sun X , Thor S , Pappas C , Zanders N , Tumpey TM , Todd Davis C , Maines TR . Emerg Microbes Infect 2022 11 (1) 1-20 Influenza A viruses (IAVs) in the swine reservoir constantly evolve, resulting in expanding genetic and antigenic diversity of strains that occasionally cause infections in humans and pose threat of emerging as a strain capable of human-to-human transmission. For these reasons, there is an ongoing need for surveillance and characterization of newly emerging strains to aid pandemic preparedness efforts, particularly for the selection of candidate vaccine viruses and conducting risk assessments. Here, we performed a parallel comparison of the pathogenesis and transmission of genetically and antigenically diverse swine-origin A(H1N1) variant (v) and A(H1N2)v, and human seasonal A(H1N1)pdm09 IAVs using the ferret model. Both groups of viruses were capable of replication in the ferret upper respiratory tract; however, variant viruses were more frequently isolated from the lower respiratory tract as compared to the human-adapted viruses. Regardless of virus origin, observed clinical signs of infection differed greatly between strains, with some viruses causing nasal discharge, sneezing and, in some instances, diarrhea in ferrets. The most striking difference between the viruses was the ability to transmit through the air. Human-adapted viruses were capable of airborne transmission between all ferret pairs. In contrast, only one out of the four tested variant viruses was able to transmit via the air as efficiently as the human-adapted viruses. Overall, this work highlights the need for sustained monitoring of emerging swine IAVs to identify strains of concern such as those that are antigenically different from vaccine strains and that possess adaptations required for efficient respiratory droplet transmission in mammals. |
Addressing personal protective equipment (PPE) decontamination: Methylene blue and light inactivates severe acute respiratory coronavirus virus 2 (SARS-CoV-2) on N95 respirators and medical masks with maintenance of integrity and fit.
Lendvay TS , Chen J , Harcourt BH , Scholte FE , Lin YL , Kilinc-Balci FS , Lamb MM , Homdayjanakul K , Cui Y , Price A , Heyne B , Sahni J , Kabra KB , Lin YC , Evans D , Mores CN , Page K , Chu LF , Haubruge E , Thiry E , Ludwig-Begall LF , Wielick C , Clark T , Wagner T , Timm E , Gallagher T , Faris P , Macia N , Mackie CJ , Simmons SM , Reader S , Malott R , Hope K , Davies JM , Tritsch SR , Dams L , Nauwynck H , Willaert JF , De Jaeger S , Liao L , Zhao M , Laperre J , Jolois O , Smit SJ , Patel AN , Mayo M , Parker R , Molloy-Simard V , Lemyre JL , Chu S , Conly JM , Chu MC . Infect Control Hosp Epidemiol 2021 43 (7) 1-83 OBJECTIVE: The coronavirus disease 2019 (COVID-19) pandemic has resulted in shortages of personal protective equipment (PPE) underscoring the urgent need for simple, efficient, and inexpensive methods to decontaminate SARS-CoV-2-exposed masks and respirators. We hypothesized that methylene blue (MB) photochemical treatment, which has various clinical applications, could decontaminate PPE contaminated with coronavirus. DESIGN: The two arms of the study included: 1) PPE inoculation with coronaviruses followed by MB with light (MBL) decontamination treatment, and 2) PPE treatment with MBL for 5 cycles of decontamination (5CD) to determine maintenance of PPE performance. METHODS: MBL treatment was used to inactivate coronaviruses on three N95 filtering facepiece respirator (FFR) and two medical mask (MM) models. We inoculated FFR and MM materials with three coronaviruses, including SARS-CoV-2, and treated with 10 µM MB and exposed to 50,000 lux of white light or 12,500 lux of red light for 30 minutes. In parallel, integrity was assessed after 5CD using multiple US and international test methods and compared to the FDA-authorized vaporized hydrogen peroxide plus ozone (VHP+O3) decontamination method. RESULTS: Overall, MBL robustly and consistently inactivated all three coronaviruses with 99.8 - to >99.9% virus inactivation across all FFRs and MMs tested. FFR and MM integrity was maintained after 5 cycles of MBL treatment, whereas one FFR model failed after 5 cycles of VHP+O3. CONCLUSIONS: MBL treatment decontaminated respirators and masks by inactivating three tested coronaviruses without compromising integrity through 5CD. MBL decontamination is effective, low-cost and does not require specialized equipment, making it applicable in all-resource settings. |
Genetically and antigenically divergent influenza A(H9N2) viruses exhibit differential replication and transmission phenotypes in mammalian models.
Belser JA , Sun X , Brock N , Pappas C , Pulit-Penaloza JA , Zeng H , Jang Y , Jones J , Carney PJ , Chang J , Van Long N , Diep NT , Thor S , Di H , Yang G , Cook PW , Creager HM , Wang D , McFarland J , Van Dong P , Wentworth DE , Tumpey TM , Barnes JR , Stevens J , Davis CT , Maines TR . J Virol 2020 94 (17) Low pathogenicity avian influenza A(H9N2) viruses, enzootic in poultry populations in Asia, are associated with fewer confirmed human infections but higher rates of seropositivity compared to A(H5) or A(H7) subtype viruses. Co-circulation of A(H5) and A(H7) viruses leads to the generation of reassortant viruses bearing A(H9N2) internal genes with markers of mammalian adaptation, warranting continued surveillance in both avian and human populations. Here, we describe active surveillance efforts in live poultry markets in Vietnam in 2018 and compare representative viruses to G1 and Y280 lineage viruses that have infected humans. Receptor binding properties, pH thresholds for HA activation, in vitro replication in human respiratory tract cells, and in vivo mammalian pathogenicity and transmissibility were investigated. While A(H9N2) viruses from both poultry and humans exhibited features associated with mammalian adaptation, one human isolate from 2018, A/Anhui-Lujiang/39/2018, exhibited increased capacity for replication and transmission, demonstrating the pandemic potential of A(H9N2) viruses.IMPORTANCE A(H9N2) influenza viruses are widespread in poultry in many parts of the world, and for over twenty years, have sporadically jumped species barriers to cause human infection. As these viruses continue to diversify genetically and antigenically, it is critical to closely monitor viruses responsible for human infections, to ascertain if A(H9N2) viruses are acquiring properties that make them better suited to infect and spread among humans. In this study, we describe an active poultry surveillance system established in Vietnam to identify the scope of influenza viruses present in live bird markets and the threat they pose to human health. Assessment of a recent A(H9N2) virus isolated from an individual in China in 2018 is also reported and was found to exhibit properties of adaptation to humans and, importantly, show similarities to strains isolated from the live bird markets of Vietnam. |
Comparison of nucleic acid extraction methods for next-generation sequencing of avian influenza A virus from ferret respiratory samples.
Di H , Thor S , Trujillo AA , Stark T , Marinova-Petkova A , Jones J , Wentworth DE , Barnes J , Davis CT . J Virol Methods 2019 270 95-105 Influenza A virus is a negative-sense RNA virus with a segmented genome consisting of eight RNA segments. Avian influenza A virus (AIV) primarily infects avian hosts and sporadically infects mammals, which can lead to adaptation to new species. Next-generation sequencing (NGS) of emerging AIV genomes extracted from respiratory samples collected on sequential days from animal models and clinical patients enables analysis of the emergence of evolutionary variants within the virus population over time. However, obtaining codon complete AIV genome at a sufficient coverage depth for nucleotide variant calling remains a challenge, especially from post-inoculation respiratory samples collected at late time points that have low viral titers. In this study, nasal wash samples from ferrets inoculated with different subtypes of AIV were collected on various days post-inoculation. Each nasal wash sample was aliquoted and extracted using five commercially available nucleic acid extraction methods. Extracted influenza virus RNA was amplified and NGS conducted using Illumina Mi-Seq. For each nasal wash sample, completeness of AIV genome segments and coverage depth were compared among five extraction methods. Nucleic acids extracted by MagNA pure compact RNA isolation consistently yielded codon complete sequences for all eight genome segments at the required coverage depth at each time point sampled. The study revealed that DNase treatment was critical to the amplification of influenza genome segments and the downstream success of codon complete NGS from nasal wash samples. The findings from this study can be applied to improve NGS of influenza and other RNA viruses that infect the respiratory tract and are collected from respiratory samples. |
Attenuation of highly pathogenic avian influenza A(H5N1) viruses in Indonesia following the reassortment and acquisition of genes from low pathogenicity avian influenza A virus progenitors.
Dharmayanti Nlpi , Thor SW , Zanders N , Hartawan R , Ratnawati A , Jang Y , Rodriguez M , Suarez DL , Samaan G , Pudjiatmoko , Davis CT . Emerg Microbes Infect 2018 7 (1) 147 The highly pathogenic avian influenza (HPAI) A(H5N1) virus is endemic in Indonesian poultry and has caused sporadic human infection in Indonesia since 2005. Surveillance of H5N1 viruses in live bird markets (LBMs) during 2012 and 2013 was carried out to provide epidemiologic and virologic information regarding viral circulation and the risk of human exposure. Real-time RT-PCR of avian cloacal swabs and environmental samples revealed influenza A-positive specimens, which were then subjected to virus isolation and genomic sequencing. Genetic analysis of specimens collected at multiple LBMs in Indonesia identified both low pathogenicity avian influenza (LPAI) A(H3N8) and HPAI A(H5N1) viruses belonging to clade 2.1.3.2a. Comparison of internal gene segments among the LPAI and HPAI viruses revealed that the latter had acquired the PB2, PB1, and NS genes from LPAI progenitors and other viruses containing a wild type (wt) genomic constellation. Comparison of murine infectivity of the LPAI A(H3N8), wt HPAI A(H5N1) and reassortant HPAI A(H5N1) viruses showed that the acquisition of LPAI internal genes attenuated the reassortant HPAI virus, producing a mouse infectivity/virulence phenotype comparable to that of the LPAI virus. Comparison of molecular markers in each viral gene segment suggested that mutations in PB2 and NS1 may facilitate attenuation. The discovery of an attenuated HPAI A(H5N1) virus in mice that resulted from reassortment may have implications for the capability of these viruses to transmit and cause disease. In addition, surveillance suggests that LBMs in Indonesia may play a role in the generation of reassortant A(H5) viruses and should be monitored. |
Antigenic characterization of highly pathogenic avian influenza A(H5N1) viruses with chicken and ferret antisera reveals clade-dependent variation in hemagglutination inhibition profiles
Thi Nguyen D , Shepard SS , Burke DF , Jones J , Thor S , Nguyen LV , Nguyen TD , Balish A , Hoang DN , To TL , Iqbal M , Wentworth DE , Spackman E , van Doorn HR , Davis CT , Bryant JE . Emerg Microbes Infect 2018 7 (1) 100 Highly pathogenic avian influenza (HPAI) A(H5N1) viruses pose a significant economic burden to the poultry industry worldwide and have pandemic potential. Poultry vaccination against HPAI A(H5N1) viruses has been an important component of HPAI control measures and has been performed in Vietnam since 2005. To systematically assess antigenic matching of current vaccines to circulating field variants, we produced a panel of chicken and ferret antisera raised against historical and contemporary Vietnamese reference viruses representing clade variants that were detected between 2001 and 2014. The antisera were used for hemagglutination inhibition (HI) assays to generate data sets for analysis by antigenic cartography, allowing for a direct comparison of results from chicken or ferret antisera. HI antigenic maps, developed with antisera from both hosts, revealed varying patterns of antigenic relationships and clustering of viruses that were dependent on the clade of viruses analyzed. Antigenic relationships between existing poultry vaccines and circulating field viruses were also aligned with in vivo protection profiles determined by previously reported vaccine challenge studies. Our results establish the feasibility and utility of HPAI A(H5N1) antigenic characterization using chicken antisera and support further experimental and modeling studies to investigate quantitative relationships between genetic variation, antigenic drift and correlates of poultry vaccine protection in vivo. |
Antigenically diverse swine-origin H1N1 variant influenza viruses exhibit differential ferret pathogenesis and transmission phenotypes.
Pulit-Penaloza JA , Jones J , Sun X , Jang Y , Thor S , Belser JA , Zanders N , Creager HM , Ridenour C , Wang L , Stark TJ , Garten R , Chen LM , Barnes J , Tumpey TM , Wentworth DE , Maines TR , Davis CT . J Virol 2018 92 (11) Influenza A(H1) viruses circulating in swine represent an emerging virus threat as zoonotic infections occur sporadically following exposure to swine. A fatal infection caused by an H1N1 variant (H1N1v) virus was detected in a patient with reported exposure to swine and who presented with pneumonia, respiratory failure, and cardiac arrest. To understand the genetic and phenotypic characteristics of the virus, genome sequence analysis, antigenic characterization, and ferret pathogenesis and transmissibility experiments were performed. Antigenic analysis of the virus isolated from the fatal case, A/Ohio/09/2015, demonstrated significant antigenic drift away from classical swine H1N1 variant viruses and H1N1 pandemic 2009 viruses. A substitution in the H1 hemagglutinin (G155E) was identified that likely impacted antigenicity, and reverse genetics was employed to understand the molecular mechanism of antibody escape. Reversion of the substitution to 155G, in a reverse genetics A/Ohio/09/2015 virus, showed that this residue was central to the loss of hemagglutination inhibition by ferret antisera raised against a prototypical H1N1 pandemic 2009 virus (A/California/07/2009), as well as gamma lineage classical swine H1N1 viruses, demonstrating the importance of this residue for antibody recognition of this H1 lineage. When analyzed in the ferret model, A/Ohio/09/2015 and another H1N1v virus (A/Iowa/39/2015), as well as A/California/07/2009, replicated efficiently in the respiratory tract of ferrets. The two H1N1v viruses transmitted efficiently among cohoused ferrets, but respiratory droplet transmission studies showed that A/California/07/2009 transmitted through the air more efficiently. Pre-existing immunity to A/California/07/2009 did not fully protect ferrets from challenge with A/Ohio/09/2015.IMPORTANCE Human infections with classical swine influenza A(H1N1) viruses that circulate in pigs continue to occur in the United States following exposure to swine. To understand the genetic and virologic characteristics of a virus (A/Ohio/09/2015) associated with a fatal infection and a virus associated with a non-fatal infection (A/Iowa/39/2015), we performed genome sequence analysis, antigenic testing, and pathogenicity and transmission studies in a ferret model. Reverse genetics was employed to identify a single antigenic site substitution (HA G155E) responsible for antigenic variation of A/Ohio/09/2015 compared to related classical swine influenza A(H1N1) viruses. Ferrets with pre-existing immunity to the pandemic A(H1N1) virus were challenged with A/Ohio/09/2015 demonstrating decreased protection. This data illustrates the potential for currently circulating swine influenza viruses to infect and cause illness in humans with pre-existing immunity to H1N1 pandemic 2009 viruses and a need for ongoing risk assessment and development of candidate vaccine viruses for improved pandemic preparedness. |
Avian influenza A(H7N2) virus in human exposed to sick cats, New York, USA, 2016
Marinova-Petkova A , Laplante J , Jang Y , Lynch B , Zanders N , Rodriguez M , Jones J , Thor S , Hodges E , De La Cruz JA , Belser J , Yang H , Carney P , Shu B , Berman L , Stark T , Barnes J , Havers F , Yang P , Trock SC , Fry A , Gubareva L , Bresee JS , Stevens J , Daskalakis D , Liu D , Lee CT , Torchetti MK , Newbury S , Cigel F , Toohey-Kurth K , St George K , Wentworth DE , Lindstrom S , Davis CT . Emerg Infect Dis 2017 23 (12) 2046-9 An outbreak of influenza A(H7N2) virus in cats in a shelter in New York, NY, USA, resulted in zoonotic transmission. Virus isolated from the infected human was closely related to virus isolated from a cat; both were related to low pathogenicity avian influenza A(H7N2) viruses detected in the United States during the early 2000s. |
Assessment of Molecular, Antigenic, and Pathological Features of Canine Influenza A(H3N2) Viruses That Emerged in the United States.
Pulit-Penaloza JA , Simpson N , Yang H , Creager HM , Jones J , Carney P , Belser JA , Yang G , Chang J , Zeng H , Thor S , Jang Y , Killian ML , Jenkins-Moore M , Janas-Martindale A , Dubovi E , Wentworth DE , Stevens J , Tumpey TM , Davis CT , Maines TR . J Infect Dis 2017 216 S499-s507 Background: A single subtype of canine influenza virus (CIV), A(H3N8), was circulating in the United States until a new subtype, A(H3N2), was detected in Illinois in spring 2015. Since then, this CIV has caused thousands of infections in dogs in multiple states. Methods: In this study, genetic and antigenic properties of the new CIV were evaluated. In addition, structural and glycan array binding features of the recombinant hemagglutinin were determined. Replication kinetics in human airway cells and pathogenesis and transmissibility in animal models were also assessed. Results: A(H3N2) CIVs maintained molecular and antigenic features related to low pathogenicity avian influenza A(H3N2) viruses and were distinct from A(H3N8) CIVs. The structural and glycan array binding profile confirmed these findings and revealed avian-like receptor-binding specificity. While replication kinetics in human airway epithelial cells was on par with that of seasonal influenza viruses, mild-to-moderate disease was observed in infected mice and ferrets, and the virus was inefficiently transmitted among cohoused ferrets. Conclusions: Further adaptation is needed for A(H3N2) CIVs to present a likely threat to humans. However, the potential for coinfection of dogs and possible reassortment of human and other animal influenza A viruses presents an ongoing risk to public health. |
Update: Increase in human infections with novel Asian lineage avian influenza A(H7N9) viruses during the fifth epidemic - China, October 1, 2016-August 7, 2017
Kile JC , Ren R , Liu L , Greene CM , Roguski K , Iuliano AD , Jang Y , Jones J , Thor S , Song Y , Zhou S , Trock SC , Dugan V , Wentworth DE , Levine MZ , Uyeki TM , Katz JM , Jernigan DB , Olsen SJ , Fry AM , Azziz-Baumgartner E , Davis CT . MMWR Morb Mortal Wkly Rep 2017 66 (35) 928-932 Among all influenza viruses assessed using CDC's Influenza Risk Assessment Tool (IRAT), the Asian lineage avian influenza A(H7N9) virus (Asian H7N9), first reported in China in March 2013, is ranked as the influenza virus with the highest potential pandemic risk. During October 1, 2016-August 7, 2017, the National Health and Family Planning Commission of China; CDC, Taiwan; the Hong Kong Centre for Health Protection; and the Macao CDC reported 759 human infections with Asian H7N9 viruses, including 281 deaths, to the World Health Organization (WHO), making this the largest of the five epidemics of Asian H7N9 infections that have occurred since 2013. This report summarizes new viral and epidemiologic features identified during the fifth epidemic of Asian H7N9 in China and summarizes ongoing measures to enhance pandemic preparedness. Infections in humans and poultry were reported from most areas of China, including provinces bordering other countries, indicating extensive, ongoing geographic spread. The risk to the general public is very low and most human infections were, and continue to be, associated with poultry exposure, especially at live bird markets in mainland China. Throughout the first four epidemics of Asian H7N9 infections, only low pathogenic avian influenza (LPAI) viruses were detected among human, poultry, and environmental specimens and samples. During the fifth epidemic, mutations were detected among some Asian H7N9 viruses, identifying the emergence of high pathogenic avian influenza (HPAI) viruses as well as viruses with reduced susceptibility to influenza antiviral medications recommended for treatment. Furthermore, the fifth-epidemic viruses diverged genetically into two separate lineages (Pearl River Delta lineage and Yangtze River Delta lineage), with Yangtze River Delta lineage viruses emerging as antigenically different compared with those from earlier epidemics. Because of its pandemic potential, candidate vaccine viruses (CVV) were produced in 2013 that have been used to make vaccines against Asian H7N9 viruses circulating at that time. CDC is working with partners to enhance surveillance for Asian H7N9 viruses in humans and poultry, to improve laboratory capability to detect and characterize H7N9 viruses, and to develop, test and distribute new CVV that could be used for vaccine production if a vaccine is needed. |
Shifting clade distribution, reassortment, and emergence of new subtypes of highly pathogenic avian influenza A(H5) viruses collected in Vietnamese poultry from 2012 to 2015.
Nguyen DT , Jang Y , Nguyen TD , Jones J , Shepard SS , Yang H , Gerloff N , Fabrizio T , Nguyen LV , Inui K , Yang G , Creanga A , Wang L , Mai DT , Thor S , Stevens J , To TL , Wentworth DE , Nguyen T , Pham DV , Bryant JE , Davis CT . J Virol 2016 91 (5) Whole genome sequences of representative highly pathogenic avian influenza A(H5) viruses from Vietnam were generated, comprising samples from poultry outbreaks and active market surveillance collected from January 2012 to August 2015. Six hemagglutinin gene clades were characterized. Clade 1.1.2 was predominant in southern Mekong provinces throughout 2012 and 2013, but gradually disappeared and was not detected after April 2014. Clade 2.3.2.1c viruses spread rapidly during 2012 and were detected in the south and center of the country. A number of clade 1.1.2 and 2.3.2.1c inter-clade reassortant viruses were detected with different combinations of internal genes derived from 2.3.2.1a and 2.3.2.1b viruses indicating extensive co-circulation. Although reassortment generated genetic diversity at the genotype level, there was relatively little genetic drift within the individual gene segments suggesting genetic stasis over recent years. Antigenically, clade 1.1.2, 2.3.2.1a, 2.3.2.1b, 2.3.2.1c viruses remained related to earlier viruses and WHO recommended pre-pandemic vaccine strains representing these clades. Clade 7.2 viruses, although only detected in small numbers, were the exception as indicated by introduction of a genetically and antigenically diverse strain in 2013. Clade 2.3.4.4 viruses (H5N1 and H5N6) were likely introduced in April 2014 and appeared to gain dominance across northern and central regions. Antigenic analyses of clade 2.3.4.4 viruses compared to existing clade 2.3.4 candidate vaccine viruses (CVV) indicated the need for an updated vaccine virus. A/Sichuan/26221/2014 (H5N6), was developed and ferret antisera generated against this virus was demonstrated to inhibit some but not all clade 2.3.4.4 viruses suggesting consideration of alternative clade 2.3.4.4 CVVs. IMPORTANCE: Highly pathogenic avian influenza (HPAI) A(H5) viruses have circulated continuously in Vietnam since 2003 resulting in hundreds of poultry outbreaks and sporadic human infections. Despite significant reduction in the number of human infections in recent years, poultry outbreaks continue to occur and the virus continues to diversify. Vaccination of poultry has been used as a means to control spread and impact of the virus but due to the diversity and changing distribution of antigenically distinct viruses, the utility of vaccines in the face of mismatched circulating strains remains questionable. This study assesses the putative amino acid changes in viruses leading to antigenic variability, underscoring the complexity of vaccine selection for both veterinary and public health purposes. Given the overlapping geographic distribution of multiple, antigenically distinct clades of HPAI A(H5) viruses in Vietnam, the vaccine efficacy of bivalent poultry vaccine formulations should be tested in the future. |
Genetic Diversity and Protective Efficacy of the RTS,S/AS01 Malaria Vaccine.
Neafsey DE , Juraska M , Bedford T , Benkeser D , Valim C , Griggs A , Lievens M , Abdulla S , Adjei S , Agbenyega T , Agnandji ST , Aide P , Anderson S , Ansong D , Aponte JJ , Asante KP , Bejon P , Birkett AJ , Bruls M , Connolly KM , D'Alessandro U , Dobano C , Gesase S , Greenwood B , Grimsby J , Tinto H , Hamel MJ , Hoffman I , Kamthunzi P , Kariuki S , Kremsner PG , Leach A , Lell B , Lennon NJ , Lusingu J , Marsh K , Martinson F , Molel JT , Moss EL , Njuguna P , Ockenhouse CF , Ragama Ogutu B , Otieno W , Otieno L , Otieno K , Owusu-Agyei S , Park DJ , Pellé K , Robbins D , Russ C , Ryan EM , Sacarlal J , Sogoloff B , Sorgho H , Tanner M , Theander T , Valea I , Volkman SK , Yu Q , Lapierre D , Birren BW , Gilbert PB , Wirth DF . N Engl J Med 2015 373 (21) 2025-2037 BACKGROUND: The RTS,S/AS01 vaccine targets the circumsporozoite protein of Plasmodium falciparum and has partial protective efficacy against clinical and severe malaria disease in infants and children. We investigated whether the vaccine efficacy was specific to certain parasite genotypes at the circumsporozoite protein locus. METHODS: We used polymerase chain reaction-based next-generation sequencing of DNA extracted from samples from 4985 participants to survey circumsporozoite protein polymorphisms. We evaluated the effect that polymorphic positions and haplotypic regions within the circumsporozoite protein had on vaccine efficacy against first episodes of clinical malaria within 1 year after vaccination. RESULTS: In the per-protocol group of 4577 RTS,S/AS01-vaccinated participants and 2335 control-vaccinated participants who were 5 to 17 months of age, the 1-year cumulative vaccine efficacy was 50.3% (95% confidence interval [CI], 34.6 to 62.3) against clinical malaria in which parasites matched the vaccine in the entire circumsporozoite protein C-terminal (139 infections), as compared with 33.4% (95% CI, 29.3 to 37.2) against mismatched malaria (1951 infections) (P=0.04 for differential vaccine efficacy). The vaccine efficacy based on the hazard ratio was 62.7% (95% CI, 51.6 to 71.3) against matched infections versus 54.2% (95% CI, 49.9 to 58.1) against mismatched infections (P=0.06). In the group of infants 6 to 12 weeks of age, there was no evidence of differential allele-specific vaccine efficacy. CONCLUSIONS: These results suggest that among children 5 to 17 months of age, the RTS,S vaccine has greater activity against malaria parasites with the matched circumsporozoite protein allele than against mismatched malaria. The overall vaccine efficacy in this age category will depend on the proportion of matched alleles in the local parasite population; in this trial, less than 10% of parasites had matched alleles. (Funded by the National Institutes of Health and others.). |
Generation and Characterization of Live Attenuated Influenza A(H7N9) Candidate Vaccine Virus Based on Russian Donor of Attenuation.
Shcherbik S , Pearce N , Balish A , Jones J , Thor S , Davis CT , Pearce M , Tumpey T , Cureton D , Chen LM , Villanueva J , Bousse TL . PLoS One 2015 10 (9) e0138951 BACKGROUND: Avian influenza A (H7N9) virus has emerged recently and continues to cause severe disease with a high mortality rate in humans prompting the development of candidate vaccine viruses. Live attenuated influenza vaccines (LAIV) are 6:2 reassortant viruses containing the HA and NA gene segments from wild type influenza viruses to induce protective immune responses and the six internal genes from Master Donor Viruses (MDV) to provide temperature sensitive, cold-adapted and attenuated phenotypes. METHODOLOGY/PRINCIPAL FINDINGS: LAIV candidate A/Anhui/1/2013(H7N9)-CDC-LV7A (abbreviated as CDC-LV7A), based on the Russian MDV, A/Leningrad/134/17/57 (H2N2), was generated by classical reassortment in eggs and retained MDV temperature-sensitive and cold-adapted phenotypes. CDC-LV7A had two amino acid substitutions N123D and N149D (H7 numbering) in HA and one substitution T10I in NA. To evaluate the role of these mutations on the replication capacity of the reassortants in eggs, the recombinant viruses A(H7N9)RG-LV1 and A(H7N9)RG-LV2 were generated by reverse genetics. These changes did not alter virus antigenicity as ferret antiserum to CDC-LV7A vaccine candidate inhibited hemagglutination by homologous A(H7N9) virus efficiently. Safety studies in ferrets confirmed that CDC-LV7A was attenuated compared to wild-type A/Anhui/1/2013. In addition, the genetic stability of this vaccine candidate was examined in eggs and ferrets by monitoring sequence changes acquired during virus replication in the two host models. No changes in the viral genome were detected after five passages in eggs. However, after ten passages additional mutations were detected in the HA gene. The vaccine candidate was shown to be stable in the ferret model; post-vaccination sequence data analysis showed no changes in viruses collected in nasal washes present at day 5 or day 7. CONCLUSIONS/SIGNIFICANCE: Our data indicate that the A/Anhui/1/2013(H7N9)-CDC-LV7A reassortant virus is a safe and genetically stable candidate vaccine virus that is now available for distribution by WHO to vaccine manufacturers. |
Detection and Characterization of Clade 1 Reassortant H5N1 Viruses Isolated from Human Cases in Vietnam during 2013.
Thor SW , Nguyen H , Balish A , Hoang AN , Gustin KM , Nhung PT , Jones J , Thu NN , Davis W , Ngoc TN , Jang Y , Sleeman K , Villanueva J , Kile J , Gubareva LV , Lindstrom S , Tumpey TM , Davis CT , Long NT . PLoS One 2015 10 (8) e0133867 Highly pathogenic avian influenza (HPAI) H5N1 is endemic in Vietnamese poultry and has caused sporadic human infection in Vietnam since 2003. Human infections with HPAI H5N1 are of concern due to a high mortality rate and the potential for the emergence of pandemic viruses with sustained human-to-human transmission. Viruses isolated from humans in southern Vietnam have been classified as clade 1 with a single genome constellation (VN3) since their earliest detection in 2003. This is consistent with detection of this clade/genotype in poultry viruses endemic to the Mekong River Delta and surrounding regions. Comparison of H5N1 viruses detected in humans from southern Vietnamese provinces during 2012 and 2013 revealed the emergence of a 2013 reassortant virus with clade 1.1.2 hemagglutinin (HA) and neuraminidase (NA) surface protein genes but internal genes derived from clade 2.3.2.1a viruses (A/Hubei/1/2010-like; VN12). Closer analysis revealed mutations in multiple genes of this novel genotype (referred to as VN49) previously associated with increased virulence in animal models and other markers of adaptation to mammalian hosts. Despite the changes identified between the 2012 and 2013 genotypes analyzed, their virulence in a ferret model was similar. Antigenically, the 2013 viruses were less cross-reactive with ferret antiserum produced to the clade 1 progenitor virus, A/Vietnam/1203/2004, but reacted with antiserum produced against a new clade 1.1.2 WHO candidate vaccine virus (A/Cambodia/W0526301/2012) with comparable hemagglutination inhibition titers as the homologous antigen. Together, these results indicate changes to both surface and internal protein genes of H5N1 viruses circulating in southern Vietnam compared to 2012 and earlier viruses. |
Identification of molecular markers associated with alteration of receptor-binding specificity in a novel genotype of highly pathogenic avian influenza A(H5N1) viruses detected in Cambodia in 2013.
Rith S , Davis CT , Duong V , Sar B , Horm SV , Chin S , Ly S , Laurent D , Richner B , Oboho I , Jang Y , Davis W , Thor S , Balish A , Iuliano AD , Sorn S , Holl D , Sok T , Seng H , Tarantola A , Tsuyuoka R , Parry A , Chea N , Allal L , Kitsutani P , Warren D , Prouty M , Horwood P , Widdowson MA , Lindstrom S , Villanueva J , Donis R , Cox N , Buchy P . J Virol 2014 88 (23) 13897-909 Human infections with influenza A(H5N1) virus in Cambodia increased sharply during 2013. Molecular characterization of viruses detected in clinical specimens from human cases revealed the presence of mutations associated with alteration of receptor-binding specificity (K189R, Q222L) and respiratory droplet transmission in ferrets (N220K with Q222L). Discovery of quasispecies at position 222 (Q/L), in addition to absence of the mutations in poultry/environmental samples, suggested the mutations occurred during human infection and did not transmit further. |
Emergence of multiple clade 2.3.2.1 influenza A (H5N1) virus subgroups in Vietnam and detection of novel reassortants
Creanga A , Thi Nguyen D , Gerloff N , Thi Do H , Balish A , Dang Nguyen H , Jang Y , Thi Dam V , Thor S , Jones J , Simpson N , Shu B , Emery S , Berman L , Nguyen HT , Bryant JE , Lindstrom S , Klimov A , Donis RO , Davis CT , Nguyen T . Virology 2013 444 12-20 Phylogenetic analyses of 169 influenza A(H5N1) virus genomes were conducted for samples collected through active surveillance and outbreak responses in Vietnam between September 2010 and September 2012. While clade 1.1 viruses persisted in southern regions, three genetically distinct subgroups of clade 2.3.2.1 were found in northern and central Vietnam. The identification of each subgroup corresponded with detection of novel reassortants, likely due to their overlapping circulation throughout the country. While the previously identified clade 1.1 and A/Hubei/1/2010-like 2.3.2.1 genotypes remained the predominant viruses detected, four viruses were found to be reassortants between A/Hubei/1/2010-like (HA, NA, PB2, PB1, PA, NP) and A/duck/Vietnam/NCVD-885/2010-like (M, NS) viruses and one virus was identified as having A/duck/Vietnam/NCVD-885/2010-like HA, NA, PB1, and NP with A/Hubei/1/2010-like PB2 and PA genes. Additionally, clade 2.3.2.1 A/Hong Kong/6841/2010-like viruses, first detected in mid-2012, were identified as reassortants comprised of A/Hubei/1/2010-like PB2 and PA and A/duck/Vietnam/NCVD-885/2010-like PB1, NP, NA, M, NS genes. |
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