Detection and characterisation of porcine circoviruses in wild boars in northeastern Serbia

The objective was to expand and update the knowledge on the presence and genotype diversity of porcine circoviruses 2 and 3 (PCV2 and PCV3) in the wild boar populations from the hunting grounds in northeastern Serbia. The presence of PCV3 was not determined, and PCV2 was confirmed in 40.32% of the organ samples from 124 wild boars hunted from 2018 to 2019, indicating their significance in virus circulation since traditional pig farms with irregular PCV2 vaccination strategies are widespread in this region. The most prevalent genotype was PCV2d, followed by PCV2b and PCV2a in 55.6%, 38.9%, and 5.5% of the examined samples, respectively. Nucleotide sequences of the detected strains were homogenous within the genotype and clustered within the subgroups PCV2d-2, PCV2b-1A/B, and PCV2a-2D with high identity to European, Chinese, and Serbian domestic pig sequences suggesting their origin. Wild boars presented with no clinical or pathological signs of infection, implying that these animals might be less susceptible to disease, particularly since the cofactors present in pig farming systems that support the disease development are absent in the wild. The high PCV2 detection frequency demonstrates the importance of wildlife monitoring to track virus population dynamics, especially in regions with free-range pig farming in order to plan adequate disease control strategies.

Vaccination of Sows against Porcine Circovirus Type 2 (PCV2) in a Subclinically Infected Herd Does Not Impact Reproductive Performance

Porcine circovirus type 2 (PCV2) vaccination in piglets has become one of the crucial and indisputable procedures in modern swine production. The role of PCV2 vaccination in breeding animals is less explored. In the present study, the evaluation of the impact of sow vaccination on reproductive parameters was performed in a high health status, PCV2 subclinically infected herd of 3200 sows. The comparison of the number of liveborn, stillborn, and weak born piglets between groups of sows vaccinated on 1 or 28 days after weaning, or nonvaccinated, did not show any statistically significant differences. Although in the tested farm the vaccination of sows appeared to have no effect on reproductive performance, the results should not be generalized. Careful and individualized analysis of diagnostic and production data is crucial in economizing infectious disease control programs in sow herds and pig populations.

The effect of porcine circovirus type 2 (PCV2) vaccination of male piglets on sperm quality at the age of puberty

The objective of the study was to investigate the effect of porcine circovirus type 2 (PCV2) vaccination in piglets on sperm quality of young boars. A total of 136 sows were divided in four groups of 34 animals each (17 vaccinated with Circovac®, Merial and 17 unvaccinated in each group). A total of 1 200 piglets were selected, half of which were vaccinated against PCV2 on the 21st day (Porcilis® PCV, MSD) and the other half was left unvaccinated. Four groups of 300 pigs each were formed as follows: PS group (vaccinated sows + piglets), S group (vaccinated sows + unvaccinated piglets), P group (unvaccinated sows + vaccinated piglets), C group (unvaccinated sows + piglets). Furthermore, 80 boars (20 piglets per group) were selected and slaughtered at the age of 5.5 months and weight of 95 ± 5.5 kg and their epididymal sperm was collected and evaluated for motility and kinetics, concentration and morphology. Additionally, 10 pigs from each group were used for blood sampling and serological testing for PCV2 IgM and IgG antibodies at the age of 21, 70, 110 and 150 days. The IgG and IgM patterns suggested that the piglets were coming into contact with PCV2 early in life. The S group demonstrated significantly lower curvilinear velocity (VCL, μm/s), amplitude of lateral head displacement (ALH, μm) and significantly higher head abnormalities (%) compared to other groups (P < 0.05). In conclusion, vaccinated young boars showed some improved epididymal sperm kinetic indices and head morphology.

Cross-sectional study on viraemia and shedding of porcine circovirus type 2 in a subclinically infected multiplier sow herd

Vertical and horizontal transmission of porcine circovirus type 2 (PCV2) plays an important role for the spread of PCV2 within piglet-producing farms and following production steps. Further information is crucial to learn about the principles of PCV2 circulation among sows in piglet-producing farms to improve preventive healthcare concerning porcine circovirus diseases (PCVD) in downstream production steps. The present study was conducted as a cross-sectional study in a 400 sow multiplier herd in Germany with no PCV2 vaccination. Blood, faeces and saliva of the sows in all stages of production were tested for PCV2-DNA by real-time PCR. Results were analysed under respect of the parity and stage of production of the sows. PCV2-DNA in faeces or saliva was observed especially in young sows. Highest rates of viraemia in productive sows were found in the early stages of pregnancy. The results revealed that particularly gilts from the quarantine and rearing area and sows up to the second parity play a major role for the spread of PCV2 and thus for the maintenance of PCV2 infection in sow herds. Furthermore, the stage of production had a significant influence on the detection rate of PCV2-DNA in serum, saliva or faeces of the sows.