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

Naomi Ariyama,Valentina Valdés,Belén Agüero,Victor Neira,Sergio Bucarey,Barbara Brito,Sunil Mor,Felipe Berrios

doi:10.3389/fvets.2021.789491

Naomi Ariyama, Valentina Valdés + Show 6 more

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https://doi.org/10.3389/fvets.2021.789491

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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.

Highlights

Porcine circoviruses (PCVs) are small (12–23 nm), nonenveloped, icosahedral, circular single-stranded DNA viruses [1]
Porcine Circovirus 2 (PCV2) is the most studied PCVs species due to its pathogenic potential, associated with multiple clinical conditions [2]. These are known as porcine circovirusassociated diseases (PCVAD); including the PCV2 systemic disease, formerly post-weaning multisystemic wasting syndrome (PMWS), and diverse respiratory, reproductive, intestinal, and neurological syndromes [3,4,5]
Due to the rapid emergence and spread of PCV2 genotypes, this study aims to review the current distribution of PCV2 genetic types in Chile

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Introduction

Porcine circoviruses (PCVs) are small (12–23 nm), nonenveloped, icosahedral, circular single-stranded DNA viruses [1]. Porcine Circovirus 2 (PCV2) is the most studied PCVs species due to its pathogenic potential, associated with multiple clinical conditions [2]. These are known as porcine circovirusassociated diseases (PCVAD); including the PCV2 systemic disease, formerly post-weaning multisystemic wasting syndrome (PMWS), and diverse respiratory, reproductive, intestinal, and neurological syndromes [3,4,5]. The most common PCV2 manifestation is subclinical [5]. PCV2 losses were estimated at £88 million/year in England only, with subclinical infections causing higher costs than clinical manifestations [5, 6]

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