Porcine Circovirus 3 Strains Research Articles

High detection frequency and genetic diversity of porcine circovirus 3 (PCV-3) in Namibian backyard farms and warthogs

Since its first identification in 2015, porcine circovirus 3 (PCV-3) has been reported worldwide with a high frequency and in the presence of several clinical conditions, although its impact on pig health and productivity is still debated. Data on the presence of PCV-3 in Africa are, however, limited. A previous study performed on commercial pigs in Namibia failed to identify the pathogen. In the present study, the viral circulation in backyard farms, characterised by lower biosecurity measures and frequent animal exchange between farms, was assessed. The susceptibility of warthogs to PCV-3 infection and their potential epidemiological role were also evaluated. Tonsils from 77 pigs from backyard piggeries and 55 warthogs were collected in different regions of Namibia and tested by PCR. Positive samples were sequenced and compared to PCV-3 strains circulating globally. Forty-two out of 77 pigs (54.54 %) and 12 out of 55 warthogs (21.82 %) tested positive, demonstrating the presence of PCV-3 in the country and suggesting that the high biosecurity measures implemented in the commercial farms that previously tested negative for PCV-3 probably prevented viral introduction. The partial ORF2 gene was successfully sequenced in samples from 27 pigs and 6 warthogs. Genetically, the identified strains were part of 3 distinct groups which included both backyard pigs and warthogs from different regions of Namibia. There is also evidence for the occurrence of multiple introduction events most likely from Asian countries, either directly into Namibia or through other African countries. Considering the strict Namibian regulations on live animal importation, understanding the source of viral introduction is challenging, although semen importation or the habit of feeding backyard pigs with human food waste might have played a role. Pig exchanges between farms for breeding purposes or wildlife movements could also have been involved in PCV-3 dispersal within Namibia. Despite the significant advances in the field, further studies should be undertaken to properly understand PCV-3 epidemiology in Namibia and its impact on pig productivity and wildlife health.

Porcine circoviruses in Malaysia

Abstract Over one decade since the first report, Malaysian porcine circovirus 2 (PCV2) molecular detection rates remain high at 83.78 and 83.54% for farm and sampled domestic pig population levels respectively. Clinically healthy finishers also showed a high detection rate of 94.74%. Most notably, a major genotype shift from genotype PCV2b to PCV2d was observed. PCV2 antigen was also detected in the Malaysian wild boar population, sharing significant nucleotide identity similarities with PCV2 strains of domestic pigs. Porcine circovirus 3 (PCV3), which was discovered not too long ago in 2017, has been confirmed to be present among the Malaysian commercial pig population at a molecular prevalence of 41.67% at the farm level and 17.02% at the sampled domestic pig population level respectively. Most recently, PCV4 had been detected in Malaysia, albeit at a much lower molecular prevalence of 4.08%. Both PCV4-positive samples originated from clinically healthy finishers. Phylogenetic analyses suggested the possibility of PCV3 and PCV4 being introduced by international trade activities. For practical and economic reasons, in the local Malaysian pig industry, field diagnostics of PCV2 cases generally rely on clinical and post-mortem findings, together with herd antibody titer and qPCR viremia titer. Currently, commercial PCV3 diagnostics service and vaccines are not available locally. With updated local PCV2 epidemiology, control and management efforts could be adapted into more effective strategies. A common management strategy for PCV2 challenge in farms could be applied for the time being to control potential PCV3 problems in the farms. As for PCV4, a larger number of field samples from cases of different clinical manifestations needs to be included to obtain a more accurate epidemiological picture.

Emergence of novel porcine circovirus 2d strains in Thailand, 2019-2020.

Porcine circovirus 2 (PCV2) has been recognized as a causative agent of porcine circovirus diseases (PCVDs) affecting the global swine industry. In this study, the genetic diversity of PCV2 strains circulating in Thailand between 2019 and 2020 was investigated using 742 swine clinical samples from 145 farms. The results showed PCV2-positive rates of 54.2% (402/742) and 81.4% (118/145) at the sample and farm levels, respectively. Genetic analysis of 51 Thai PCV2 genomic sequences showed that 84.3% (43/51) was PCV2d, 13.7% (7/51) was PCV2b and 1.9% (1/51) was PCV2b/2d recombinant virus. Surprisingly, the majority of the Thai PCV2d sequences from this study (69.77%, 30/43) formed a novel cluster on a phylogenetic tree and contained a unique 133HDAM136 on the ORF2 deduced amino acid sequence, which is in one of the previously identified immunoreactive domains strongly involved in virus neutralization. The PCV2b/2d recombinant virus also carried 133HDAM136. The emergence of the novel PCV2d strains predominating in Thailand was discussed. This study highlights the need for further investigations on the spreading of these PCV2d strains in other regions and the efficacy of current commercial vaccines.

Detection and Complete Genomic Analysis of Porcine circovirus 3 (PCV3) in Diarrheic Pigs from the Dominican Republic: First Report on PCV3 from the Caribbean Region.

The increasing detection of Porcine circovirus 3 (PCV3, family Circoviridae) in clinically ill pigs worldwide has raised concerns on the implications of the virus on porcine health and the pork industry. Although pork production constitutes an important component of the livestock economy and is a major source of animal protein in the Caribbean Islands, there are no reports on PCV3 in pigs from the region so far. In the present study, PCV3 was detected in 21% (21/100) of diarrheic pigs (sampled at three farms) from the Caribbean nation of the Dominican Republic (DR). Although the sample size varied between porcine age groups, the highest PCV3 detection rates (35.3% each, respectively) were observed in piglets and growers. Co-infections with PCV2 and porcine adenovirus were observed in 38.09% and 9.52% of the PCV3 positive samples, respectively. The complete genomes of 11 DR PCV3 strains were analyzed in the present study, revealing a unique deletion (corresponding to nucleotide residue at position 1165 of reference PCV3 sequences) in one of the DR PCV3 sequences. Based on sequence identities and phylogenetic analysis (open reading frame 2 and complete genome sequences), the DR PCV3 strains were assigned to genotype PCV3a, and shared high sequence homologies (>98% identities) between themselves and with those of other PCV3a (Clade-1) strains, corroborating previous observations on the genetic stability of PCV3 worldwide. To our knowledge, this is the first report on the detection and molecular characterization of PCV3 in pigs from the Caribbean region, providing important insights into the expanding global distribution of the virus, even in isolated geographical regions (the Island of Hispaniola). Our findings warrant further investigations on the molecular epidemiology and economic implications of PCV3 in pigs with diarrhea and other clinical conditions across the Caribbean region.

Epidemiological Analysis of Porcine Circovirus Type 2 (PCV2) Spatio-temporally of Circulation in Vietnam from 2004 to 2019

Introduction: Porcine circovirus 2 (PCV2) is a causative agent of postweaning multisystem wasting syndrome (PMWS), an epizootic disease that causes significant economic losses to pig producers worldwide, including Viet Nam. However, analyses of which groups of PCV2 strains cause disease in pigs in Viet Nam are still limited, leading to the delay or lack of application of specific vaccine sources to prevent PMWSs in other countries. Method: In this study, we aimed to analyze the geographical and temporal diversity of PCV2 in pig farms across 26 provinces in Vietnam, thus identifying the dominant strain for vaccine production. After samples from North, Central, and South Viet Nam were collected, phylogenetic trees were created to study the molecular genetic/evolutionary relationships, thereby classifying the existing PCV2 strains. The spatiotemporal distribution of strains is shown visually for observation. Finally, an analysis of the important evolutionary differences between the two strains, PCV2d and PCV2b, revealed that these strains were superior in Viet Nam. Results: Our study examined the diversity of PCV2 strains in Vietnam, ranging from the northern to southern regions, and the PCV2d strain was revealed to be the predominant strain. Interestingly, we observed the presence of 2 or 3 different genotypes of PCV2 in the same province and at the same time. We identified the presence of PCV2h, PCV2g, and PCV2e genotypes that had not been previously detected. Furthermore, we identified potential sites of positive selection in the capsid epitopes, which are believed to play a crucial role in evading the host immune system. Conclusions: The results showed that Viet Nam has 5 genotypes, namely, PCV2b, PCV2e, PCV2g, PCV2h and PCV2d—the main causative strains of the disease. The coexistence of strains in the same geographical area was also shown, indicating the importance of preparing vaccines and preventing livestock infection in Viet Nam.

Coinfections of African swine fever virus, porcine circovirus 2 and 3, and porcine parvovirus 1 in swine in Nigeria.

As pig production increases in Africa, it is essential to identify the pathogens that are circulating in the swine population to assess pig welfare and implement targeted control measures. For this reason, DNA samples collected from pigs in Nigeria in the context of African swine fever monitoring were further screened by PCR for porcine circovirus 2 (PCV-2), porcine circovirus 3 (PCV-3), and porcine parvovirus 1 (PPV1). Forty-seven (45%) pigs were positive for two or more pathogens. Sequence analysis identified PCV-2 genotypes a, b, and d, while limited genetic heterogenicity was observed among PCV-3 strains. All except one of the PPV1 sequences were genetically distinct from those previously identified in other countries.

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.

We report here high rates (47.5%, 48/101) of detection of porcine circovirus 2 (PCV2) in diarrheic pigs from three pig farms in the Dominican Republic. Seventeen of the PCV2 positive samples, representing the three pig farms, different age groups and sampling periods (2020–2021), were amplified for the complete PCV2 genome. Based on analysis of open reading frame 2 and complete genome sequences, the 17 PCV2 strains were assigned to the PCV2d genotype. Significant differences were observed in PCV2 detection rates between the vaccinated (20% (10/50)) and unvaccinated (62.5% (10/16) and 80% (28/35)) farms, corroborating previous observations that PCV2a-based vaccines confer protection against heterologous PCV2 genotypes. The present study is the first to report detection and molecular characterization of PCV2 from the Dominican Republic, warranting large-scale molecular epidemiological studies on PCV2 in pig farms and backyard systems across the country. For the first time, PCV2d was identified as the predominant PCV2 genotype in a study from the Caribbean region, suggesting that a genotype shift from PCV2b to PCV2d might be happening in the Caribbean region, which mirrored the current PCV2 genotype scenario in many other parts of the world. Besides PCV2, we also identified a pigeon circovirus-like virus, and a circular Replication-associated protein (Rep)-encoding single-stranded (CRESS) DNA virus, which was characterized for the complete genome. The CRESS DNA virus shared a similar genomic organization and was related to unclassified CRESSV2 DNA viruses (belonging to the Order Cirlivirales) from porcine feces in Hungary, indicating that related unclassified CRESS DNA viruses are circulating among pigs in different geographical regions, warranting further studies on the epidemiology and biology of these novel viruses.

Genotype Shift of Malaysian Porcine Circovirus 2 (PCV2) from PCV2b to PCV2d within a Decade.

Simple SummaryThis study aims to provide an updated Malaysian porcine circovirus 2 (PCV2) situation after a knowledge gap of one decade. Molecular detection rates of 83.78% and 83.54% at farm and sample population level were reported, close to previous publication. However, an obvious genotype shift from genotype PCV2b to PCV2d was revealed. Substitution rate for PCV2 cap gene sequences in this study was estimated at 1.102 × 10−3 substitutions/site/year, in agreement with the high substitution rate expected from PCV2 strains. Phylogenetic clustering pattern according to the year of sample origin was observed, suggesting possible nucleotide mutation occurring over time. Concurrent circulation of different PCV2 strains within one farm and within a single individual were also observed. This study also reports detection of PCV2 antigen across all production age groups from fetuses to sows; in abattoir lung samples from clinically healthy finishers; and in the wild boar population roaming Peninsular Malaysia. These observations of high molecular detection rates in farms, clinically healthy abattoir samples and in the wild boar population; and most importantly, a new wave of genotype shift from PCV2b to PCV2d—warrant further attention on the Malaysian PCV2 situation pertinent to the control and management strategy applicable to local swine farming.This paper aims to update the molecular status of porcine circovirus 2 (PCV2) in Malaysia. Firstly, the molecular detection rate of PCV2 in farm and sampled pig population were reported to be 83.78% (31/37 farms) and 83.54% (66/79 pigs) positive for PCV2, respectively. PCV2 was detected across all age groups, from fetuses, porkers to sows. Co-detection of PCV2 and PCV3 antigens was also reported at a rate of 28.77% (21/73). Secondly, PCV2 antigen was also detected in Malaysian abattoir lung samples: 18 out of 19 (94.74%) samples originating from clinically healthy finishers were tested positive. Further, this is the first study to confirm the circulation of PCV2 in the wild boar population roaming Peninsular Malaysia, where 28 out of 28 (100%) wild boar lung samples were found positive. One decade earlier, only genotype PCV2b was reported in Malaysia. This most recent update revealed that genotypes PCV2a, PCV2b and PCV2d were present, with PCV2d being the predominant circulating genotype. PCV2 cap gene nucleotide sequences in this study were found to be under negative selection pressure, with an estimated substitution rate of 1.102 × 10−3 substitutions/site/year (ssy).

Phylogenetic analysis of porcine circovirus 3 circulating in Canadian pigs

IntroductionPorcine circovirus 3 (PCV3) has been detected in pigs worldwide and associated with several clinical signs.MethodsTo investigate the genetic diversity of PCV3 strains circulating in Canada, 44 PCV3 positive samples from Saskatchewan (2/44), Manitoba (2/44), Quebec (4/44), Alberta (11/44) and Ontario (25/44) submitted to diagnostic laboratories in Canada between 2019 and 2021 were sequenced and analyzed.ResultsPhylogenetic analysis of capsid genes showed that all of the 44 Canadian strains classified into PCV3a and segregated into seven lineages with common amino acid changes observed at A24V, R27K, N56D, T77S, Q98R, L150I (F) and R168K positions.ConclusionFuture studies are required to determine whether the polymorphisms in capsid proteins, as revealed in this study, could be associated with differences in the pathogenicity or antigenicity of PCV3 strains. This is the first phylogenetic analysis of PCV3 strains among different provinces in Canada.

A retrospective study reveals the Porcine circovirus-2f genotype predominant in the indigenous pig population of North-eastern India.

Porcine circovirus-2 (PCV2) is a widespread virus and presents sub-clinically in most of the swineherd. Globally, eight genotypes of PCV2 have been identified that is PCV2a to 2h. To determine the region-wide genotype distribution of PCV2 infection, with additional reference to indigenous breeds, a total of 1314 pig's clinical samples from the eight states of North-eastern India between 2011 and 2014; were analyzed. The overall prevalence rate of PCV2 in this region was 28.2% (370/1314) by PCR. The state-wise PCR based PCV2 prevalence rate was: Tripura (20.8%), Nagaland (25.0%), Meghalaya (25.8%), Assam (32.1%), Sikkim (32.6%), Manipur (33.3%), Mizoram (36.7%) and Arunachal Pradesh (42.3%). Subsequently, a total of 29 complete genomes of PCV2 were amplified and sequenced from these PCV2 positive samples. The phylogenetic tree represents that the 29 PCV2 isolates of this study were divided into four distinct genetic groups; PCV2a, PCV2b, PCV2d, and PCV2f. Among these, 14 PCV2 strains were classified as PCV2f, 13 classified as PCV2d, and one isolate of each classified as PCV2a and PCV2b. All the 14 PCV2f strains appeared from indigenous pigs of this region. Based on the date of collection, the present study further describes that the PCV2f genotypes circulate in the indigenous pigs' population back in 2011. The amino acid residues and the atomic coordinate structure (3D model) of PCV2f capsid protein represents similarity to PCV2d capsid protein support the efficacy of the existing PCV2 vaccine against the PCV2f. The observation of this study helps to understand the genotype distribution of PCV2 and stands as a reference for future molecular epidemiological studies in North-eastern India.

Evidence of coinfection of pigs with African swine fever virus and porcine circovirus 2.

Archival swine DNA samples from Indonesia and Mongolia, some of which were previously shown to be positive for African swine fever virus, were screened for the presence of porcine circovirus 2 (PCV-2) and porcine circovirus 3 (PCV-3) by PCR. Samples from both countries were positive for PCV-2 (three from Mongolia and two from Indonesia), while none were positive for PCV-3. The PCV-2 amplicons were sequenced, and phylogenetic analysis revealed that the PCV-2 strains belonged to four different genotypes: PCV-2a (Mongolia), PCV-2b (Mongolia and Indonesia), PCV-2d (Indonesia), and PCV-2g (Mongolia). This is the first report of ASFV/PCV-2 coinfection in pigs and the first report of the presence of PCV-2 in Mongolia.

Genotyping of Porcine Circovirus 2 (PCV-2) in Vaccinated Pigs Suffering from PCV-2-Systemic Disease between 2009 and 2020 in Spain.

Vaccination against porcine circovirus 2 (PCV-2) is a common practice all over the world. Vaccines can prevent PCV-2-systemic disease (PCV-2-SD) outbreaks but not PCV-2 infection, which can be detectable in a percentage of vaccinated animals. Occasionally, PCV-2-SD is diagnosed in vaccinated farms. The objective of this study was to genotype the PCV-2 strains detected in vaccinated animals diagnosed with PCV-2-SD. Additionally, the evolution of the frequency of PCV-2 genotype detection at Spanish, European, and world levels was assessed. Fifty cases diagnosed as PCV-2-SD between 2009 and 2020 were included in this study. PCV-2 genotype was determined by sequencing the Cap gene region. Among them, only PCV-2b (23/50, 46%) and PCV-2d (27/50, 54%) genotypes were detected. Although the frequency of detection of these two genotypes was similar, their temporal distribution was different. Whereas most PCV-2b sequences (17/23, 74%) were detected between 2009 and 2012, PCV-2d sequences were obtained from 2013 to 2020. Indeed, a predominance of the PCV-2d genotype was observed from 2013 onwards, a trend also noticed at European and world levels. The results suggest that detection of particular genotypes in vaccinated animals probably reflects the general prevalence of the genotypes over time rather than genotype-specific vaccine-immunity escaping.

Porcine circovirus 3 in North and South America: Epidemiology and genetic diversity.

Porcine circovirus 3 (PCV3) is a recently discovered virus that has been detected in the swine population worldwide. PCV3 infection has been associated with several signs, but its pathogenicity is currently uncertain. This review article aimed to analyse the PCV3 strains that circulate in different countries in North and South America. We demonstrated the main regions of polymorphisms in the capsid protein structure. Furthermore, we found that PCV3 has at least six different lineages circulating in the Americas. Additional studies are required to determine the role of PCV3 in different clinical syndromes and its epidemiology in swine herds in North and South American countries.

Genetic diversity of porcine circovirus 3 strains and the first detection of two different PCV3 strains coinfecting the same host in Minas Gerais, Brazil.

Porcine circovirus 3 (PCV3) is a recently emerged circovirus discovered in 2016 that has drawn the attention of the swine industry worldwide. In this study, we evaluated the genetic diversity of PCV3 strains on pig farms. A total of 261 samples from sows, weaning pigs, growing pigs, and stillborn/mummified fetuses were analyzed by quantitative real-time PCR. The results revealed that at least two main lineages of PCV3 are circulating in Brazil. For the first time, it was possible to detect the presence of two different PCV3 strains in the same host.

Porcine Circovirus Type 3 in Pig Farms Experiencing Diarrhea in Jiangxi, China: Prevalence, Genome Sequence and Pathogenicity.

Simple SummaryPorcine circovirus 3 (PCV3) is a new species of PCV that was associated with porcine dermatitis and nephropathy syndrome (PDNS), respiratory disease, cardiac and multisystem inflammation in nursery and finishing pigs, and reproductive failure problems, including abortion, mummified fetuses, and stillbirth in sows. To date, the reports on the PCV3 present in diarrhea pigs are limited and the genetic characteristics of PCV3 from diarrheal pigs and pathogenicity on pigs were inconsistent. This study aimed to investigate the prevalence of PCV3 in pigs with/without diarrhea, to analyze the genome sequence of PCV3 from diarrheal pigs, and to inquire into the associated pathogenicity of PCV3 to piglets experimentally infected with PCV3-positive intestinal contents. The results demonstrated that PCV3 was widely circulating in diarrheal suckling and weaned piglets. Clinical signs, gross lesions, and histological changes were observed in suckling piglets inoculated with PCV3. The complete genome of a PCV3a strain was determined and two mutations (V24A and K27R) were present when compared with PCV3b strains. The findings of this study increase the knowledge of the epidemiology, viral genetics, pathogenicity, and pathogenesis of PCV3.Porcine circovirus 3 (PCV3) infections have been reported in different clinical presentations. However, the prevalence and pathogenicity of PCV3 associated with diarrhea in piglets have been limited. Herein, we present an investigation and genome analyses of PCV3 in piglets experiencing diarrhea, and observed clinical signs, gross lesions, and histological changes in pigs negative for all known pathogens associated with diarrhea but positive for PCV3 alone. Among the feces (n = 141) tested, 16.31% (23/141) were positive for PCV3. Of which, 27.28% (15/55) and 14.29% (5/35) were present in diarrheal samples from suckling and weaned piglets, respectively. Moderate to severe atrophic villi was confined in duodenum, jejunum, and ileum, and significantly decreased average heights of villi, and the depths of crypt were observed in PCV3-infected piglets. The complete genome of a representative strain of PCV3, designated as JX/CH/2018, was determined. Multialignment analysis indicated that JX/CH/2018 had 97.7–99.7% nucleotide identity at the complete genome level, and 97.2–100% at the amino acid level of the capsid protein when compared with reference PCV3 strains. Phylogenetic analysis showed that the PCV3 strain identified in this study belonged to PCV3a lineage. The present study demonstrated that PCV3 is a common virus in diarrheal suckling and weaned piglets.

Detection and phylogenetic analysis of porcine circovirus 3 in part of northern China from 2016 to 2018.

Porcine circovirus 3 (PCV3) is a recently identified virus that is associated with reproductive failure, porcine dermatitis and nephropathy syndrome, and multi-systemic inflammation. To investigate the molecular epidemic characteristics and genetic evolution of PCV3 in northern China, a commercial TaqMan-based real-time quantitative PCR kit was used to detect PCV3 in 435 tissue specimens collected from pigs with various clinical signs from 105 different swine farms in northern China. The results showed that 48 out of 105 (45.7%) farms and 97 out of 435 (22.3%) samples tested positive for PCV3. Of the 97 PCV3-positive samples, 80 (82.5%) tested positive for other pathogens. PCV3 was found more frequently in pigs with reproductive failure than in those with other clinical signs. This study is the first to detect PCV3 in Tianjin. The complete genome sequences of six PCV3 isolates and the capsid (Cap) protein gene sequences of 11 isolates were determined. Based on the predicted amino acids at positions 24 and 27 of the Cap protein and their evolutionary relationships, the 17 PCV3 strains obtained from northern China and 49 reference strains downloaded from the GenBank database were divided into four major groups (3a-3d). An analysis of selection pressure and polymorphism indicated that the PCV3 Cap protein seems to be evolving under balancing selection, that the population is in dynamic equilibrium, and that no population expansion occurred during the study period. Our results provide new information about the molecular epidemiology and evolution of PCV3.

Genetic Characterization of Porcine Circovirus 3 Strains Circulating in Sardinian Pigs and Wild Boars.

Porcine circovirus 3 (PCV3) is a recently discovered member of the Circoviridae family. So far, its presence has been reported in North America, Asia, South America, and Europe. In this study, blood and tissue samples from 189 Sardinian suids (34 domestic pigs, 115 feral free ranging pigs, and 39 wild boars) were used to genetically characterize the PCV3 strains from Sardinia. PCV3 infection in the animals was confirmed by real time PCR. The detection rate in the three groups analyzed was l7.64% in domestic pigs, 77.39% in free ranging pigs, and 61.54% in wild boars. Moreover, our results showed that co-infection of PCV3 with other viruses is quite a common occurrence. Molecular characterization of Sardinian PCV3 strains was performed by sequencing 6 complete genomes and 12 complete cap genes. Our results revealed that there is a high similarity between our strains and those identified in different countries, confirming the genetic stability of PCV3 regardless of geographical origin. Haplotype network analysis revealed the presence of 6 whole genomes or 12 unique ORF2 haplotypes and a nonsynonymous mutation in ORF2 that leads to an R14K amino acid substitution. Phylogenetic analysis of whole genome and ORF2 was also conducted. The Sardinian strains were allocated in three different clusters of phylogenetic trees of both complete genome and ORF2. With this study, we have provided a snapshot of PCV3 circulation in Sardinia. Our findings might help to achieve a deeper understanding of this emerging porcine virus.

High rates of detection and complete genomic analysis of porcine circovirus 2 (PCV2) in the Lesser Antilles island of St. Kitts: Identification of PCV2b-PCV2d recombinants.

Although porcine circovirus 2 (PCV2) is an economically important pathogen of swine, there is a lack of information on PCV2 from the Lesser Antilles. In this retrospective study, we report high rates of detection of PCV2 DNA in porcine faecal (41.3%, 26/63) and kidney (32.8%, 20/61) samples from the Lesser Antilles island of St. Kitts. Most of the PCV2-positive faecal samples were from diarrhoeic piglets (23/26), with 15 animals exhibiting stunted growth and/or weight loss. Although the PCV2-positive kidneys were from slaughter age, clinically healthy pigs, microscopically, various degrees of inflammation (mild, moderate or severe) were observed in 18 kidneys. Rotavirus-A, porcine parvovirus and torque teno sus virus were detected in 2, 4 and 14 PCV2-positive samples, respectively. The complete genomes of 18 St. Kitts PCV2 strains were amplified using three overlapping nested PCR assays designed in the present study. By phylogenetic analysis of PCV2 open reading frame 2 (ORF2) and complete genomes, 15 St. Kitts strains were assigned to genotype PCV2b. The remaining three PCV2 strains were identified as PCV2b-PCV2d recombinants, with the involvement of ORF2 in two of the strains. To our knowledge, this is the first report on detection and genotyping of PCV2 strains from the Lesser Antilles. Considering the significant contributions of pig farming to the regional livestock economy and increasing demand for local pork in the Lesser Antilles, our findings emphasize the importance of future studies on surveillance and genotyping of PCV2 in other Caribbean islands of the region.

Detection and genetic characterization of porcine circovirus 3 (PCV3) in pigs in India.

Porcine circovirus type 3 (PCV3), a novel circovirus, has been reported recently from major swine growing countries globally, and the virus is associated with diseases like porcine dermatitis, nephropathy syndrome and reproductive failure. This report describes the identification of PCV3 associated with reproductive failure in sows and piglet mortality and circulation of the virus in healthy pigs in India. The pathological changes in various tissues from stillborn piglet and characterization of the virus genomes were reported. The genome sequences of Indian PCV3 strains showed 91.4%-99.8% nucleotide identity with other sequences of PCV3 strains circulating worldwide. The phylogenetic analysis showed clustering of Indian strains into a separate group with the isolate from USA (MN/2016) under PCV3a genotype. The results confirmed the circulation of PCV3 in Indian pigs and its association with clinical cases. This study speculates emergence of PCV3 as an important pig pathogen in the country, which warrants the thorough investigation on PCV3 epidemiology, pathogenesis and to implement the control measures.

Porcine circovirus type 3 detection in a Hungarian pig farm experiencing reproductive failures.

Porcine circovirus 3 (PCV3) infection has been reported in piglets and sows with porcine dermatitis and nephropathy syndrome, reproductive failure, and cardiac and multisystemic inflammation. Few studies linked PCV3 infection to increased incidence of abortion and weak-born piglets. This is the first report of a detection of PCV3 Hungarian strain in several organs of aborted and weak-born piglets, including the thymus, lymph node, placenta, spleen, kidney and the liver. The tissue tropism of PCV3 in affected litters was analysed using real-time quantitative PCR, and the result showed the highest load of viral DNA in the thymus and lymph nodes. The ORF2 of Hungarian PCV3 strains was 524 nucleotides in length, and the sequence identity to GenBank sequences ranged from 98.5 per cent to 99.2 per cent. The results suggest that PCV3 may have a relevant role in reproductive failure in gilts.