Viral co-infections of the porcine respiratory tract: Insight into the local cytokine response

Infections of the porcine respiratory tract are frequently multifactorial, with more than one pathogen involved. They have a significant impact on the efficiency of pig production. One example of such a mixed infection is the porcine respiratory disease complex (PRDC). PRDC can be caused by various viral or bacterial agents. The main viral agents associated with PRDC and considered the primary pathogens are porcine reproductive and respiratory syndrome virus (PRRSV), swine influenza virus (SIV), and porcine circovirus type 2 (PCV2). PRRSV, SIV, and PCV2 are known as inducers of inflammatory cytokines. Cytokines play an important role in all aspects of immune responses, but their uncontrolled release in virus-induced diseases may aggravate the course of the disease and the severity of pathological lesions. Although data regarding the kinetics of the local cytokine response in porcine lungs during mono-infection with these pathogens are abundant, their impact on each other during simultaneous infection in different combinations is not thoroughly understood. This paper aims to present the available data on interactions between SIV, PRRSV, and PCV2 in mixed infections of the porcine respiratory tract and the influence of co-infections on local cytokine profiles in the lungs.

A candidate multi-epitope vaccine against porcine reproductive and respiratory syndrome virus and Mycoplasma hyopneumoniae induces robust humoral and cellular response in mice.

Porcine reproductive and respiratory syndrome virus (PRRSV) and Mycoplasma hyopneumoniae (M. hyopneumoniae, Mhp) are two of the most common pathogens involved in the porcine respiratory disease complex (PRDC) resulting in significant economic losses worldwide. Vaccination is the most effective approach to disease prevention. Since PRRSV and Mhp co-infections are very common, an efficient dual vaccine against these pathogens is required for the global swine industry. Compared with traditional vaccines, multi-epitope vaccines have several advantages, they are comparatively easy to produce and construct, are chemically stable, and do not have an infectious potential. In this study, to develop a safe and effective vaccine, B cell and T cell epitopes of PRRSV-GP5, PRRSV-M, Mhp-P46, and Mhp-P65 protein had been screened to construct a recombinant epitope protein rEP-PM that has good hydrophilicity, strong antigenicity, and high surface accessibility, and each epitope is independent and complete. After immunization in mice, rEP-PM could induce the production of high levels of antibodies, and it had good immunoreactivity with anti-rEP-PM, anti-PRRSV, and anti-Mhp antibodies. The anti-rEP-PM antibody specifically recognizes proteins from PRRSV and Mhp. Moreover, rEP-PM induced a Th1-dominant cellular immune response in mice. Our results showed that the rEP-PM protein could be a potential candidate for the development of a safe and effective multi-epitope peptide combined vaccine to control PRRSV and Mhp infections.