Mycoplasma hyopneumoniae vaccination influence on porcine reproductive and respiratory syndrome virus and mycoplasma hyopneumoniae coinfection

Abstract

Simultaneous vaccination against porcine reproductive and respiratory syndrome virus and Mycoplasma hyopneumoniae can decrease the efficacy of the separate vaccination. The aim of present research was to clarify whether immunization against M. hyopneumoniae only protects against porcine reproductive and respiratory syndrome development. The challenge test with both porcine reproductive and respiratory syndrome virus and M. hyopneumoniae was performed in experimental conditions on swine groups with different immune protection against M. hyopneumoniae. The experiment was conducted on twenty specific pathogen free three-month-old piglets that previously acquired varying levels of protection against M. hyopneumoniae via oral or subcutaneous vaccination. The results suggest that M. hyopneumoniae initiates the pathogenic chain of M. hyopneumoniae - porcine reproductive and respiratory syndrome virus co-infection. Simultaneously vaccinated via oral and parenteral routes animals demonstrated maximal scoring of M. hyopneumoniae lesions (5.0 against 2.0 in control group), therefore such strategy seems unreasonable. The immunization against M. hyopneumoniae undoubtedly influences the development of porcine reproductive and respiratory syndrome virus - M. hyopneumoniae co-infection, however, the interactions between infectious agents and immune defense depend on the qualitative and quantitative parameters of immunity. These interactions are multi-factorial and too complicated for an absolutely correct prognosis. The protection against M. hyopneumoniae disease development can prevent or, at least, delay porcine reproductive and respiratory syndrome in piglets and vice versa: the lung lesions and immune suppression caused by M. hyopneumoniae can open the gate to porcine reproductive and respiratory syndrome virus, which additionally complicates pathogenesis and leads to unfavorable consequences.