Phylogenetic Analysis of Porcine Circovirus Type 2 in Wild Boars from Argentina

Abstract

PCV2 ORF 2 is highly variable and allows classification of PCV2 in eight genotypes, with type ‘b’ and ‘d’ being the most prevalent in domestic swine. Wild boars are considered an important reservoir of viruses, and for this reason, our goal is to investigate the genetic diversity of PCV2 in Argentina. A total of 152 animals were captured in two seasons according to national disposition. Blood, lung, heart, kidney, spleen, liver, and lymph node samples were obtained from each animal and analyzed by virological and molecular methods. From the total samples collected during 2018–2019, 11.53% were detected as PCV2 positive by PCR. However, in 2022–2023, the percentage of positivity was 52.7% by PCR. By ELISA test, the total of positive samples from 2018 to 2019 was 71 (91%), and 55 (74%) in 2022–2023. PCV2 antigens were detected by immunohistochemistry only in the lymph node samples. From all positive PCR samples, seven sequences of the complete ORF2 gene were obtained; five were closely related to wild boar type ‘d’ strains from China and Italy, with an amino acid identity in the range of 99.14–100%, and two sequences clustered with PCV2 type ‘a’, showing an identity between 96.54 and 99.56% with a strain from Canada.