Concurrent highly pathogenic porcine reproductive and respiratory syndrome virus infection accelerates Haemophilus parasuis infection in conventional pigs

Immune response of porcine alveolar macrophages to a concurrent infection with porcine reproductive and respiratory syndrome virus and Haemophilus parasuis in vitro

“…2A). Particularly strong overproduction of IL-1b during concurrent PRRSV and H. parasuis infections could explain the occurrence of the characteristic high fever in infected pigs (Yu et al, 2012). This result validates a possible additive effect between PRRSV and secondary bacterial infection in the induction of a high pro-inflammatory cytokine response by PAMs, as was proposed by Qiao et al (2011), who reported that infection of PAMs with PRRSV and concurrent application of lipopolysaccharides resulted in significant increase of IL-1b production.…”

“…Segales et al (1999) found no differences in bacteria distribution or localization in tissues of pigs dually infected from those infected only with bacteria. More recently, Yu et al (2012) demonstrated that concurrent highly pathogenic PRRSV infection accelerates H. parasuis infection in pigs.…”

“…(Pol et al, 1997;Solano et al, 1997;Thanawongnuwech et al, 2000;Wills et al, 2000 andThanawongnuwech et al, 2004). The additive effect of PRRSV infection and a secondary bacterial infection in the induction of multifactorial respiratory diseases is recognized in the case of H. parasuis (Yu et al, 2012).…”

Concurrent infection with porcine reproductive and respiratory syndrome virus and Haemophilus parasuis in two types of porcine macrophages: apoptosis, production of ROS and formation of multinucleated giant cells

“…[20–24]. The additive effect of PRRSV infection and a secondary bacterial infection in the induction of multifactorial respiratory diseases was described in the case of H. parasuis [25, 26]. …”

Field evaluation of the efficacy, compatibility and serologic profiling of a combined vaccine against porcine reproductive and respiratory syndrome and Haemophilus parasuis in nursery pigs

“…A higher incidence of secondary bacterial infections might be due to the immunosuppressive properties of PRRSV (Done and Paton, 1995). In Asia it was proved that a highly pathogenic PRRSV accelerates an H. parasuis infection in a model with conventional pigs (Yu et al, 2012). However, field observations indicating that PRRSV leads to a higher incidence of secondary infections could not be consistently reproduced under experimental conditions .…”