Presence of Six Potentially Pathogenic Viruses in Pigs Suffering from PMWS22 October 2014
This Slovakian study examined the role of multiple virus infections in young pigs of different ages with post-weaning multisystemic wasting syndrome (PMWS). They found that the presence of PRRSV exacerbated the symptoms of PMWS and that a PCV2 vaccination reduced viral co-infections.
In a paper in BMC Veterinary Research recently, Stefan Vilcek and colleagues at the University of Veterinary Medicine and Pharmacy in Kosice, Slovakia, explain that porcine circovirus type 2 (PCV2) is an aetiological agent of porcine circovirus diseases (PCVDs). Post-weaning multisystemic wasting syndrome (PMWS) as the most important PCVD is considered a multifactorial disease.
It has previously been demonstrated that not only PCV2 but several viruses are associated with PMWS. However, studies of viral co-infections in PMWS pigs led often to controversial results.
The aim of theirwork was to determine the presence of emerging (PRRSV), re-emerging (PTV) and newly-emerging (TTSuV1, TTSuV2, PBoV1) viruses in samples of dead pigs suffering from PMWS.
The researchers also investigated the impact of vaccination against PCV2 and the influence of age on the occurrence of single and multiple viral infections in pigs.
Viruses were detected by PCR, RT-PCR and real-time PCR in the pooled tissue samples (lymph nodes, liver and spleen) of pigs with PMWS (n=56) which were divided into three groups: suckling piglets, post-weaning pigs and fattening pigs.
In addition, lymph node samples were collected from apparently healthy fattening pigs (n=59).
The effect of vaccination against PCV2 with Ingelvac CircoFlex vaccine was also investigated.
Among non-vaccinated pigs, the highest prevalence of individual viruses and multiple viral infections were found in diseased post-weaning and fattening animals with PMWS.
Severe clinical disease was observed in swine co-infected with PCV2 and PRRSV.
The prevalence of TTSuV1 and TTSuV2 was high in all groups of pigs and did not appear to have a significant effect on the syndrome.
Simultaneous infection with TTSuV1 and PBoV1 was frequently confirmed in pigs with PMWS.
No healthy pig was found to be infected with PRRSV, PTV or PBoV1.
Vaccination against PCV2 did not influence the prevalence of TTSuVs but significantly protected pigs against multiple viral infections.
Vilcek and colleagues concluded that post-weaning PMWS pigs were more often co-infected with viral pathogens than suckling or fattening pigs.
They also found that co-infection with PRRSV enforces clinical signs of PMWS but the influence of other viral co-infections was not clear.
Vaccination against PCV2 significantly reduced viral co-infections in pigs, the Kosice-based group added.
Vlasakova M., V. Leskova, I. Sliz, A. Jackova and S. Vilcek. 2014. The presence of six potentially pathogenic viruses in pigs suffering from post-weaning multisystemic wasting syndrome. BMC Veterinary Research. 10:221. doi:10.1186/s12917-014-0221-8