Update of Genetic Diversity of Porcine Circovirus Type 2 in Chile Evidences the Emergence of PCV2d Genotype

Abstract

Porcine Circovirus 2 (PCV2) can cause multiple clinical conditions known as porcine circovirus-associated diseases (PCVAD). Before the wide availability of PCV2 vaccines, PCVAD resulted in significant losses to the global swine industry. PCV2's rapid evolutionary dynamics are comparable to single-stranded RNA viruses. Thus, shifts in the dominance and distribution of different genotypes may frequently occur, resulting in the emergence and spread of varying PCV2 genotypes and recombinant strains in swine. This study aims at identifying the PCV2 genotypes currently circulating in Chile. Seven hundred thirty-eight samples were obtained from 21 swine farms between 2020 and 2021. The samples were tested using PCR for species detection and genotyping. Sequencing and phylogenetic analyses were conducted in selected samples. PCV2 was detected in 26.9% of the PCR reactions and 67% of the sampled farms. The genotypes were determined in nine farms, PCV2a in one farm, PCV2b in four, and PCV2d in five, with PCV2b and PCV2d co-circulating in one farm. The phylogenetic analysis of twelve ORF2 sequences obtained (PCV2a = 5; PCV2b = 4; PCV2d = 3) showed a PCV2a Chilean strains monophyletic cluster; closely related to Chilean viruses collected in 2012 and 2013. Of the three different PCV2b sequenced viruses, two viruses were close to the root of the PCV2b group, whereas the remaining one grouped with a South Korean virus. PCV2d sequences were closely related to Asian viruses. A previously reported PCV2a/PCV2d recombinant strain was not detected in this study. Our results suggest the emergence and potential shift to PCV2d genotype in Chilean farms.

Detection of Porcine Circovirus 1/2/3 and Genetic Analysis of Porcine Circovirus 2 in Wild Boar from Jiangxi Province of China

“…First, failure to vaccinate pigs with PCV2 leads to immune response suppression, which lowers overall production efficiency [ 18 ]. Second, it is extremely expensive to control and prevent PCV2 infection [ 19 ]. Third, compared to PCV2 negative pigs, the secondary infection rate was considerably greater in PCV2 positive pigs [ 20 ].…”

Molecular Evolution and Genotype Shift of Porcine Circoviruses Type 2 in Vietnam

“…Despite this limitation, the identi cation of both strains detected in 2007 as belonging to PCV2b provided compelling evidence supporting this evolutionary shift. The subsequent signi cant global transition of PCV2 from the PCV2b to PCV2d genotype, observed around 2012, has garnered attention as a prevailing trend in numerous countries (Kwon et al 2017;Ariyama et al 2021;Tan et al 2022). Interestingly, our study did not distinctly observe this PCV2 transition.…”

Detection and Complete Genome Analysis of Porcine Circovirus 2 (PCV2) and an Unclassified CRESS DNA Virus from Diarrheic Pigs in the Dominican Republic: First Evidence for Predominance of PCV2d from the Caribbean Region

“…For the first time, PCV2d was identified as the predominant PCV2 genotype in a study from the Caribbean region. In the Americas, PCV2d has been identified as the major PCV2 genotype in the USA [48], and recently, some South American countries have reported the emergence/genotype shift to PCV2d [30,31,49,50]. On the other hand, previous studies from the Caribbean region (Cuba and St. Kitts) reported PCV2b as the sole genotype, except for identification of 3 PCV2b-PCV2d recombinant strains from St. Kitts [36][37][38].…”