Vaccine manufacturing costs prevent a significant portion of the world's population from accessing protection from vaccinepreventable diseases. To enhance vaccine production at reduced costs, a genome-wide RNA interference (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 clustered regularly interspaced short palindromic repeat (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 replication of enterovirus 71, a clinically relevant virus to which vaccines are being targeted. The discovery that host gene modulation can markedly increase virus vaccine production dramatically alters mammalian cell-based vaccine manufacturing possibilities and should facilitate polio eradication using the inactivated poliovirus vaccine. IMPORTANCEUsing a genome-wide RNAi screen, a collection of host virus resistance genes was identified that, upon silencing, increased poliovirus and enterovirus 71 production by from 10-fold to >50-fold in a Vero vaccine manufacturing cell line. This report provides novel insights into enterovirus-host interactions and describes an approach to developing the next generation of vaccine manufacturing through engineered vaccine cell lines. The results show that specific gene silencing and knockout events can enhance viral titers of both attenuated (Sabin strain) and wild-type polioviruses, a finding that should greatly facilitate global implementation of inactivated polio vaccine as well as further reduce costs for live-attenuated oral polio vaccines. This work describes a platform-enabling technology applicable to most vaccine-preventable diseases. Vaccines are important defenses in the fight against infectious disease. Currently, a complex set of factors such as population dynamics and bioproduction costs limit the ability to provide adequate immunization coverage to many economically distressed countries. The current efforts to eradicate poliovirus exemplify these challenges. The oral polio vaccine (OPV), consisting of attenuated Sabin strains, has reduced the total number of poliomyelitis cases by Ͼ99% since the late 1980s. However, live attenuated strains carry the risk of phenotypic reversion to a neurovirulent "vaccine-derived poliovirus" (VDPV) capable of inducing vaccine-associated paralytic poliomyelitis (VAPP) (1, 2). To prevent the emergence and circulation of VDPVs during the polio eradication effort and beyond, OPV must be replaced by the inactivated poliovirus vaccine (IPV) (3). The cost of IPV, which is approximately $3.00 per dose compared to approximately $0.20 for OPV, is a major o...

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.