Comparison of pathogenicity of 4 porcine circovirus type 2 (PCV2) genotypes (2a, 2b, 2d, and 2e) in experimentally infected pigs

The objective of the current study was to compare the virulence of four porcine circovirus type 2 (PCV2) genotypes (PCV2a, 2b, 2d, and 2e) in pigs. Pigs were inoculated at 42 days of age with one of four PCV2 genotypes, then necropsied at 63 days of age. PCV2 genotype groups were evaluated through a comparison of clinical outcomes, antibody titers, level of PCV2 loads in blood and lymph nodes, and lymphoid lesion severity. Statistical differences did not occur between the evaluated genotype groups. Pigs inoculated with PCV2a, PCV2b, or PCV2d had a significantly (P<0.05) higher levels of PCV2 loads in blood and lymph node compared to pigs inoculated with PCV2e. The results of this study indicated that the PCV2a, PCV2b, and PCV2d are more virulent than PCV2e based on blood and lymphoid viral load of PCV2.