Vaccines against porcine reproductive and respiratory syndrome virus (PRRSV): writing a history

The porcine reproductive and respiratory syndrome virus (PRRSV) constitutes one of the most serious problems of the pig industry in the world. It affects pigs of all ages and causes reproductive and respiratory disorders that create great economic losses. These increase due to the rapid spread of the disease and the inefficiency of the commercial vaccines. Modified live and killed vaccines are the two types of commercial vaccines currently available on the market for American and European strains. Although these vaccines can reduce disease symptoms and viremia, they do not prevent infection in any way and cross-presentation is variable against heterologous virus. Furthermore, it has been reported that the vaccine's virus can spread to other susceptible animals. For these reason, many studies focused on the development of new vaccines that include different vectors for the development of DNA vaccines by evaluating various structural proteins. The use of PRRSV infectious clones, as well as the construction of viral chimeras between the vaccine virus and highly infectious virus have also been evaluated. All these strategies have failed to develop an effective vaccine against PRRSV; therefore it remains as a major challenge.