Vaccine manufacturing costs prevent a significant portion of the world's population from accessing protection from vaccine-preventable diseases. To enhance vaccine production at reduced costs, a genome-wide RNAi screen was performed to identify gene knockdown events that enhanced poliovirus replication. Primary screen hits were validated in a Vero vaccine manufacturing cell line using attenuated and wild type poliovirus strains. Multiple single and dual gene silencing events increased poliovirus titers >20-fold and >50-fold, respectively. Host gene knockdown events did not affect virus antigenicity and CRISPR-Cas9-mediated knockout of the top candidates dramatically improved viral vaccine strain production. Interestingly, silencing of several genes that enhanced poliovirus replication also enhanced enterovirus 71, a clinically relevant virus for which vaccines are being targeted. The discovery that host gene modulation can markedly increase virus vaccine production dramatically alters mammalian cell-based vaccine manufacturing and should facilitate polio eradication using the inactivated poliovirus vaccine. IMPORTANCE: Using a genome-wide RNAi screen, a collection of host virus-resistance genes was identified that upon silencing increased poliovirus and enterovirus 71 production from 10-fold to >50-fold in a Vero vaccine manufacturing cell line. This study provides novel insights into enterovirus-host interactions, and describes an approach toward developing the next generation of vaccine manufacturing through engineered vaccine cell lines. The findings show that specific gene silencing and knockout events can enhance viral titers of both attenuated (Sabin) and wild polioviruses, a finding that should greatly facilitate global implementation of inactivated polio vaccine, as well as further reducing costs for live-attenuated oral polio vaccines. This work describes a platform-enabling technology applicable to most vaccine preventable diseases.

Laboratories of the Dutch Working Group on Clinical Virology have routinely performed enterovirus diagnostics in the Netherlands since the early 1960s, with country-wide coverage. Enterovirus-positive samples are typed for clinical and epidemiological purposes, as well as to document the absence of poliovirus circulation. Human parechoviruses 1 and 2, initially recognized as enteroviruses, and since 2006 also the higher numbered human parechovirus types, have been detected as part of this surveillance. The purpose of this report is to describe the national enterovirus surveillance data from stool specimens collected in the Netherlands between 1996 and 2011 by all the participating laboratories. Since 2007, the average annual percentage of human enterovirus- and parechovirus-positive specimens increased from 6.5 to 10.8 % and from 0.3 to 2.5 % of the total numbers of specimens tested, respectively, following a gradual implementation of molecular diagnostics directly on clinical samples. Increased detection rates were observed for human enterovirus species A coxsackieviruses (from 0.1 to 0.5 %). Human enteroviruses of species B, C, and D were detected at average rates of 4.7, 0.04, and 0.005 %, respectively. The introduction of molecular diagnostics also resulted in an increase in the number of untyped enterovirus-positive specimens for which the presence of poliovirus was not excluded (from 1.3 to 3.1 % since 2007). To increase knowledge on human entero- and parechovirus epidemiology and type-specific pathogenesis, as well as to warrant the quality of the poliovirus surveillance in the Netherlands, it is of importance to continue the typing of enterovirus- and parechovirus-positive samples.