Inactivation and Disinfection of Poliovirus Type 1 on Nonporous Carriers

Poliovirus is a clinically relevant enterovirus from the Picornaviridae family of non-enveloped viruses. Prior to the introduction of inactivated and attenuated poliovirus vaccines in the 1950’s, the virus caused considerable global panic from 1890 onward [1]. Although the majority of poliovirus infections result in an abortive flu-like prodrome or are asymptomatic, in ~5% of infections, a meningitic phase with varying degrees of flaccid paralytic outcome follow the prodrome [2]. Enteroviruses, including polioviruses, are viruses which are transmitted through the oral/fecal route. As implied by this, oral secretions and fecal excretions from infected individuals are capable of infecting new hosts via the gastrointestinal tract of a noninfected individual. Interruption of the cycle of infection and reinfection of enteroviruses may be facilitated by disinfection interventions that are capable of inactivating the virus. In order to be of practical use, such disinfectants should cause a significant reduction in pathogen load on environmental surfaces (fomites) under ambient conditions following a relatively short contact time. Non-enveloped viruses are not susceptible to detergents or lipid solvents, and other types of chemical disinfectants must be used. For preparation of the inactivated (Salk) poliomyelitis vaccines of the 1950’s, poliovirus was inactivated with formaldehyde. Incomplete inactivation of vaccine poliovirus leading to iatrogenic poliomyelitis in ~200 individuals was attributed to the presence of viral aggregates or of an excess of foreign protein in the inactivation solutions [1]. In particular, the presence of cell debris in the vaccine pools due to inadequate purification prevented suitable exposure of the viral particles to formaldehyde, resulting in incomplete inactivation [3,4]. Protection, by viral aggregation or by sequestering in a protein matrix, of viruses from exposure to disinfectant active agents is suggested by this unfortunate case of inactivation failure. The presence of organic load at the time of deposition of a virus onto a fomite is therefore an important factor that must be considered when assessing viral inactivation efficacy.