Efficacy of a modified live porcine reproductive and respiratory syndrome virus (PRRSV) vaccine in pigs naturally exposed to a heterologous European (Italian cluster) field strain: Clinical protection and cell-mediated immunity

A New Modified Live Porcine Reproductive and Respiratory Syndrome Vaccine Improves Growth Performance in Pigs under Field Conditions

“…Clinical respiratory signs were also improved in vaccinated animals on all 3 farms. There is minimal peer-reviewed information on the efficacy of the PRRSV vaccines based on the type 2 genotype under field conditions (16,17). To our knowledge, this is the first field study of the new modified live PRRS vaccine based on the type 2 genotype.…”

Comparative Measurement of Cell-Mediated Immune Responses of Swine to the M and N Proteins of Porcine Reproductive and Respiratory Syndrome Virus

“…The GP5 and GP4 proteins are representative antigens that contribute to the induction of neutralizing antibodies (13,27). However, it has become evident that T cell-mediated immunity is essential for effective protection against PRRSV (25,47). The increased cellular immunity was significantly related to the reduced clinical symptoms in PRRSV-infected piglets and sows (17,23).…”

Porcine Herd Health Management Practices for the Control of PRRSV Infection

“…The high heterogeneity among PRRSV strains is likely to be the main obstacle to effective control of PRRSV infection using current commercial vaccines (MLV and inactivated), since the immunity induced by one strain may be only partial against a different strain, even within the same genotype (Mateu & Diaz, 2008;Kimman et al, 2009). However, vaccine efficacy may be associated with an efficient cell-mediated immunity and it is not only related with its immunological properties, but also with the characteristics of the challenging strain to trigger an immune response (Martelli et al, 2009). Therefore, the ability of each strain to induce a strong cell-mediated immune response is more important than the genetic similarity between the vaccine strain and the field strains for inducing clinical protection (Mateu & Diaz, 2008).…”

“…The protective immune response induced by current commercial MLV vaccines is influenced by genetic diversity, as these vaccines do not always sufficiently protect (or only partially) against re-infection and transplacental infections caused by heterologous strains (Scortti et al, 2006;Prieto et al, 2008;Kimman et al, 2009). However, Martelli et al (2009) reported that vaccination of piglets at 5 weeks of age with a commercial MLV vaccine induced a partial clinical protection, associated with an efficient cell-mediated immune response, when the above vaccinated pigs were exposed to a heterologous field strain. Moreover, there are major concerns about the safety of current vaccination programmes with MLV vaccines.…”