Complete genome characterization of porcine circovirus 3 recovered from wild boars in Southern Brazil

Infection and Coinfection of Porcine-Selected Viruses (PPV1 to PPV8, PCV2 to PCV4, and PRRSV) in Gilts and Their Associations with Reproductive Performance

Seven novel porcine parvoviruses (nPPVs) (PPV2 through PPV8) have been described, although their pathogenicity and possible effects on porcine reproductive failure (PRF) are undefined. In this study, these nPPVs were assessed in gilts from Colombia; their coinfections with PPV1, PCV2, PCV3, PCV4, and PRRSV and an association between the nPPVs and the reproductive performance parameters (RPPs) in sows were determined. For this, 234 serum samples were collected from healthy gilts from 40 herds in five Colombian regions, and the viruses were detected via real-time PCR. The results confirmed the circulation of PPV2 through PPV7 in Colombia, with PPV3 (40%), PPV5 (20%), and PPV6 (17%) being the most frequent. Additionally, no PCV4 or PPV8 was detected. PPV2 to PPV7 were detected in concurrence with each other and with the primary PRF viruses, and these coinfections varied from double to sextuple coinfections. Additionally, the association between nPPVs and PRF primary viruses was statistically significant for the presence of PPV6 in PCV3-positive (p < 0.01) and PPV5 in PPRSV-positive (p < 0.05) gilts; conversely, there was a significant presence of PPV3 in both PCV2-negative (p < 0.01) and PRRSV-negative (p < 0.05) gilts. Regarding the RPPs, the crude association between virus detection (positive or negative) and a high or low RPP was only statistically significant for PCV3 and the farrowing rate (FR), indicating that the crude odds of a low FR were 94% lower in herds with PCV3-positive gilts. This finding means that the detection of PCV3 in gilts (PCV3-positive by PCR) is associated with a higher FR in the farm or that these farms (with positive gilts) have lower odds (OR 0.06, p-value 0.0043) of a low FR. Additionally, a low FR tended to be associated with the detection of PPV4 and PPV5 (p-value < 0.20). This study is important for establishing the possible participation of nPPVs in PRF.

Compliance of biosecurity practices for compartmentalization to foot-mouth disease and classical swine fever viruses in commercial swine companies from southern Brazil

Classical swine fever (CSF) and foot-mouth disease (FMD) are both highly contagious disease and disruptive to commercial trades, but they are examples of foreign animal diseases that biosecurity-based compartmentalization could be used to support trade in free zones in response to an outbreak. This study aimed to evaluate biosecurity compliance to the Federal Normative Instruction #44 from December 4th, 2017 (BRAZIL, 2017) in commercial swine farms located in southern Brazil. A total of 604 swine farms from 10 commercial swine companies were sampled, from which 28.5% were breeding farms, 29.1% nursery, 32.8% finishing, 6.8% multipliers, and 2.8% farrow-to-finish. Cluster analyses revealed that farms with high compliance (n = 303, Cluster 1) performed 71% of the practices, moderate (n = 219, Cluster 2) 47%, and the low (n = 82, Cluster 3) 33%. A spatial logistic regression model estimated that biosecurity compliance was highest in only one of 10 commercial swine companies, and within a company, multipliers (when present) obtained the highest biosecurity compliance (p-value &lt; 0.01). These results suggest that major improvements in biosecurity practices are needed in breeding herds, nursery, and grow-finish farms to be compliant to the Federal Instruction #44. Based on the combination of these analyses, only one commercial swine company was more suitable to establish compartments for CSF and FMD with minimal investments. Still, this study revealed that the majority of commercial swine companies needs to improve biosecurity practice protocols to then target compartmentalization.

First complete genomic sequence analysis of porcine circovirus type 4 (PCV4) in wild boars

Porcine circovirus type 4 (PCV4), a unique circovirus with a different classification from other existing circovirus, was discovered in domestic pigs in several provinces of China. In this study, in order to investigate the epidemiology and genetic diversity of PCV4 in wild boars (Sus scrofa), a total number of 138 wild boar samples were collected from five different areas in Jiangxi Province of China, between January 2020 and December 2020. Taqman based real-time PCR were used to test PCV4 as well as PCV1, PCV2, and PCV3. Among 138 samples, 30 samples (21.7%) were positive for PCV1, 31 samples (22.5%) were positive for PCV2, 8 samples (5.8%) were positive for PCV3 and 27 samples (19.6%) were positive for PCV4, respectively. Some of the samples were co-infected with multiple PCVs. In this study, we successfully sequenced the complete genome of two PCV4 strains, which shared 98.5-99.8% of their genomic nucleotide similarity with the other five PCV4 strains discovered in domestic pigs. Phylogenetic analysis showed that the two PCV4 strains derived from wild boars were located in a closed relative branch with other PCV4 strains derived from domestic pigs, but were distinguished from other circovirus. These results of this study not only expand our understanding of the prevalence of PCVs, especially PCV4, in wild boars in Jiangxi province of China, but also showed the molecular epidemiology of PCV4. Nevertheless, the impact of wild boars infected with PCV4 on intensive farmed pigs industry remains to be further explored.

Recent Progress on Epidemiology and Pathobiology of Porcine Circovirus 3

The recently discovered porcine circovirus 3 (PCV3) belongs to the Circovirus genus of the Circoviridae family together with the other three PCVs, PCV1, PCV2, and PCV4. As reported, PCV3 can infect pig, wild boar, and several other intermediate hosts, resulting in single or multiple infections in the affected animal. The PCV3 infection can lead to respiratory diseases, digestive disorders, reproductive disorders, multisystemic inflammation, and immune responses. Up to now, PCV3 infection, as well as the disease caused by PCV3, has been reported in many swine farms worldwide with high positive rates, which indicates that the virus may be another important pathogen in the swine industry. Therefore, we reviewed the current progress on epidemiology and pathobiology of PCV3, which may provide the latest knowledge of the virus and PCV3-related diseases.

Detection of Porcine circovirus 3 from captured wild boars in Korea

Porcine circovirus 3 (PCV3) is a newly discovered ssDNA virus. The virus was first reported in pigs suffering from several clinical syndromes, including porcine dermatitis and nephropathy syndrome, reproductive disorders, respiratory disease and myocarditis. PCV3 was recently reported in wild boars with high prevalence as well. In this study, 266 wild boar anal swab, feces, nasal swab and whole blood samples were collected from three mainland provinces and one island province (Chungbuk, Gangwon, Gyeonggi, Jeju) of South Korea between 2019 and 2020 including 119 from male, 142 from female and 5 undetermined. PCV3 was diagnosed targeting conserved rep (replication associated protein) gene region using Direct PCR and sequencing. Out of 266 tested samples, 15 were positive for PCV3 with detection frequency at 5.6%. Among 266 samples tested, we obtained 14 partial rep gene sequences and one complete genome sequence of PCV3 with a genome size of 2000nt. Here we present the evidence of PCV3 circulation in Korean wild boars.

Porcine Circovirus 3a Field Strains in Free-Living Wild Boars in Paraná State, Brazil

Simple Summary

Porcine circovirus 3 (PCV-3) was first identified in pigs in the USA and was subsequently detected in several other countries, including Brazil. PCV-3 can be associated with diseases in pigs. To date, there are only a few reports of PCV-3 in wild boars worldwide. This study aimed to investigate the presence of PCV-3 in wild boars in Paraná state, Brazil. The results revealed that PCV-3 was present in the serum and lungs of the sampled boars. The complete genome of the PCV-3a strain was determined and compared with other PCV-3 strains around the world. Phylogenetic analysis has shown a close relationship to the strains already described in domestic and wild pigs. At this moment, there is no evidence that PCV-3 causes disease in wild boars. However, the monitoring of circulation of PCV-3 in wild boars is important for pig industry biosecurity because these animals share pathogens with domestic pigs.

Abstract

Porcine circovirus 3 (PCV-3) was identified in domestic pigs worldwide. Although PCV-3 has also been detected in wild boars, information regarding its circulation in this free-living animal species is scarce. To investigate PCV-3 occurrence in free-living wild boars in Brazil, 70 serum samples collected between January 2017 and June 2019 in Paraná state, Brazil were analyzed by PCR assay. Amplicons measuring 330 bp in length were amplified in seven (10.0%) of the serum samples and confirmed to be PCV3-specific by nucleotide (nt) sequencing. As the amplified products from the serum samples yielded only intermediate levels of viral DNA, lung samples from the seven PCR-positive wild boars were also evaluated by PCR. Of these samples, five lung samples were positive and provided high levels of viral DNA. The three lung samples that presented the highest levels of viral DNA were selected for amplification and sequencing of the whole PCV-3 genome. The three full-length sequences obtained were grouped in PCV-3 clade “a”, and the sequences exhibited 100% nucleotide similarity among them. The PCV-3 field strains of this study showed nucleotide and amino acid similarities of 98.5–99.8% and 98.8–100%, respectively, with whole-genome PCV-3 sequences from around the world.