[Poliovirus immunology: vaccines, problems for the prevention/eradication and future interventions]

Polio is a contagious disease that is caused by the poliovirus, an enterovirus in the family Picornaviridae. The virus enters through the oral mucosa and multiplies in epithelial cells of both the oropharynx as the gastrointestinal tract, releasing virus in oropharyngeal secretions and through the stool. The mode of transmission is fecal-oral and/or oral-oral. The virus preferentially infects children under 5 years. Most infections are asymptomatic and self-limiting gastrointestinal tract. Eventually it spreads to the central nervous system and affects the anterior horn motor neurons of the spinal cord causing paralysis and even death. We will describe host-virus interaction and the natural history of infection which depends on many factors, including the type of viral inoculum (serotypes VP1, 2 and 3) and host factors, such as nutritional status, concurrent infections and the ability to induce protective immune responses, such as, humoral anti-viral antibody responses with neutralizing antibodies, mucosal immunity and systemic adaptative immune responses. We will discuss the relevant aspects of the immuno-pathogenesis of the infection by poliovirus and the problems related to the host-virus interactions in the subjects vaccinated, with the latest advances in the strategies to develop optimal protection with the different poliovirus vaccines that could allow the development of a more effective immunization with induction of the effect or mechanisms that would prevent development of the disease, transmission of the virus, out-breaks and eventually the poliovirus eradication.