Prevalence Of Porcine Circovirus Type 2 Research Articles

Detection of PCV2d in Vaccinated Pigs in Colombia and Prediction of Vaccine T Cell Epitope Coverage against Circulating Strains Using EpiCC Analysis.

Porcine circovirus type 2 (PCV2) is strongly linked to a group of syndromes referred to as porcine-circovirus-associated diseases (PCVADs), which are controlled through vaccination; however, this does not induce sterilizing immunity but is instead involved in the evolution of the virus and is considered a factor in vaccine failure. This study sampled 84 herds (167 pigs) vaccinated against PCV2 and with clinical signs of PCVADs in five provinces across Colombia. PCV2 was identified and further characterized at the molecular level via genotyping and phylogenetic reconstructions. In addition, PCV2-associated lesions were examined via histopathology. Furthermore, the PCV2-Cap sequences retrieved were compared with three vaccines via the EpiCC tool and T cell epitope coverage. The prevalence of PCV2 was 82% in pigs and 92.9% in herds. The highest viral loads were identified in lymphoid tissue, and PCV2d emerged as the most predominant in pigs and herds (93.4% and 92.3%). Sequences for PCV2-ORF2 (n = 57; 55 PCV2d and 2 PCV2a) were determined, and PCV2d sequences were highly similar. The most common pneumonia pattern was suppurative bronchopneumonia, while the most common lung lesion was exudation in the airways; in lymphoid tissue, there was lymphoid depletion. The bivalent vaccine (PCV2a and PCVb) exhibited a higher EpiCC score (8.36) and T cell epitope coverage (80.6%) than monovalent PCV2a vaccines. In conclusion, PCV2d currently circulates widely in Colombia. Despite vaccination, there are clinical cases of PCV2, and immunoinformatic analyses demonstrate that bivalent vaccines improved the average coverage.

Investigation of porcine circovirus type 2 and porcine circovirus type 3 infections based on dual TaqMan fluorescent quantitative PCR method and genetic evolutionary analysis of these two viruses.

Porcine circovirus type 2 (PCV2) is the pathogen of Porcine Circovirus Associated Diseases. Porcine circovirus type 3 (PCV3) is a novel porcine circovirus associated with porcine dermatitis and nephropathy syndrome (PDNS) and reproductive failure. PCV2 is clearly pathogenic, while the pathogenicity of PCV3 remains controversial, so it is crucial to monitor the prevalence of PCV2 and PCV3 in healthy and diseased pigs to investigate the effects of PCV3 and PCV2 on the health status of pigs. Here, we developed a PCV2 and PCV3 dual TaqMan quantitative PCR (qPCR) method to test samples from healthy and diseased pigs, to clarify the differences in the positive rates and viral copy numbers of PCV2 and PCV3, and to analyze the genetic evolution and molecular characterization of the viral genomes obtained with sequence alignment and phylogenetic analysis, homology and structural analysis of Cap proteins, and selection pressure analysis. We successfully established a dual TaqMan qPCR method for PCV2 and PCV3 with good repeatability, specificity and sensitivity. In total, 1,385 samples from 15 Chinese provinces were tested with the established qPCR. The total positive rates were 37.47% for PCV3 and 57.95% for PCV2, and the coinfection rate for was 25.49%. The positive rates of PCV3 and PCV2 in 372 healthy pigs were 15.05 and 69.89%, respectively, and the coinfection rate was 12.90%. The positive rates of PCV3 and PCV2 in 246 diseased pigs were 55.69 and 83.33%, respectively, and the coinfection rate was 47.97%. Eighteen PCV3 genomes and 64 PCV2 genomes were identified, including nine each of the PCV3a-1 and PCV3b genotypes, eight of PCV2a, 16 of PCV2b, and 40 of PCV2d. The amino acid identity within the PCV3 Cap proteins was 94.00-100.0%, whereas the PCV2 Cap proteins showed an identity of 81.30-100.0%. PCV3 Cap was most variable at amino acid sites 24, 27, 77, 104 and 150, whereas PCV2 Cap had 10-13 unique sites of variation between genotypes. These results clarify the prevalence and variations of PCV2 and PCV3 in healthy and diseased pigs, which will provide a basis for the prevention and control of the two viral infections.

Complete genome sequence of a porcine circovirus type 2 strain, PCV2/CN/GD/2018/10, obtained in Guangdong, China, in 2018.

Porcine circovirus type 2 (PCV2) poses significant issue for the global swine industry. We conducted a comprehensive analysis of the complete genome sequence of a Chinese PCV2 strain belonging to genotype PCV2a, which was designated as PCV2/CN/GD/2018/10. Our findings provide insights into the prevalence of PCV2 in China.

Prevalence and phylogenetic analysis of porcine circovirus type 2 (PCV2) and type 3 (PCV3) in the Southwest of China during 2020-2022.

Porcine circovirus type 2 (PCV2) is considered one of the viruses with substantial economic impact on swine industry in the word. Recently, porcine circovirus type 3 (PCV3) has been found to be associated with porcine dermatitis and nephropathy syndrome (PDNS)-like disease. And the two viruses were prone to co-infect clinically. To further investigate the prevalence and genetic diversity of the two viruses, 257 pig samples from 23 different pig farms in southwest China with suspected PCVAD at different growth stages were analyzed by real-time PCR between 2020 and 2022 to determine the presence of PCV2 and PCV3. Results showed high prevalence of PCV2 and PCV3: 26.46% samples were PCV2 positive and 33.46% samples were PCV3 positive. The coinfection rate was doubled from 2020 (5.75%) to 2022 (10.45%). Subsequently, the whole genome sequences of 13 PCV2 and 18 PCV3 strains were obtained in this study. Of these, 1 strain was PCV2a, 5 strains were PCV2b and 7 strains were PCV2d, indicating that PCV2d was the predominant PCV2 genotype prevalent in the Southwest of China. In addition, the phylogenetic analysis of PCV3 showed high nucleotide homology (>98%) between the sequences obtained in this study and reference sequences. And 3 mutations (A24V, R27K and E128D) were found in PCV3 antibody recognition domains, which might be related to the mechanism of viral immune escape. Thus, this study will enhance our understanding of the molecular epidemiology and evolution of PCV2 and PCV3, which are conducive to the further study of the genotyping, immunogenicity and immune evasion of PCVs.

Prevalence and genetic diversity of porcine circovirus type 2 in northern Guangdong Province during 2016–2021

The emergence and widespread of porcine circovirus-associated diseases (PCVADs), mainly caused by porcine circovirus type 2 (PCV2), threatens the Chinese swine industry. In this study, to investigate the recent prevalence of PCV2 in northern Guangdong Province of China, 573 tissue samples from 132 pig farms were collected during 2016–2021 and analyzed via PCR. Overall, 51.38% (297/573, 95%CI 47.74–55.92) samples were tested PCV2 positive. The detection rate of PCV2 was significantly lower in samples collected before 2016-2018 than after the outbreak of African Swine Fever (2019-2021), being 59.85% (158/264, 95%CI 53.94–65.76) and 41.47% (141/340, 95%CI 36.43–46.71), respectively. On the other end, the genetic characteristics of 26 PCV2 strains were further analyzed. These PCV2 strains belonged to three genotypes, including PCV2a, PCV2b, and PCV2d. Specifically, the predominant genotype prevalent during two periods (2016–2018 and 2019–2021) wasPCV2b (81.82%, 9/11) and PCV2d (80.0%, 12/15), respectively. The results above illustrated the high prevalence and the genetic evolution feature of PCV2 in Guangdong Province in recent years.

Prevalence of Porcine Circoviruses in Slaughterhouses in Central Shanxi Province, China.

BackgroundPorcine circovirus disease is currently the greatest threat to pig farming. Four main porcine circovirus genotypes are circulating worldwide.ObjectiveThe study aimed to assess the prevalence of porcine circovirus genotypes in the central part of Shanxi province.MethodsWe investigated the prevalence of porcine circovirus type 2 (PCV2), porcine circovirus type 3 (PCV3), and porcine circovirus type 4 (PCV4). Porcine circoviruses were analyzed by polymerase chain reaction (PCR) in the lung tissues of 180 pigs from 7 slaughterhouses in central Shanxi, China.ResultsThe prevalence of PCV2, PCV3, and PCV4 were 56.8, 80, and 9.4%, respectively, and the negative rate was 10% for all three pathogens. The co-infection with PCV2 + PCV3, PCV2 + PCV4, PCV3 + PCV4, and PCV2 + PCV3 + PCV4 were 47.2, 7.4, 7.4, and 5.6%, respectively. Among PCV4-positive samples, the positive rate of PCV4 + PCV2 was 52.9% (9/17), whereas that of PCV4 + PCV3 was 100% (17/17). On the other hand, PCV2 and PCV3 were detected in 57.1% (93/163) and in 78.5% (128/163) of PCV4-negative samples, respectively. Phylogenetic analysis demonstrated that PCV2, PCV3, and PCV4 were not in the same clade and were distant from each other.ConclusionThe high positive rates of PCV3, PCV2 + PCV3, and PCV3 + PCV4 suggest that PCV3 may play a decisive role in PCV2 and PCV4 infections. Therefore, further control of PCV3 is needed to reduce the spread of the virus.

Genetic Diversity of Porcine Circovirus 2 in Wild Boar and Domestic Pigs in Ukraine.

Porcine circovirus type 2 (PCV2) is responsible for a number of porcine circovirus-associated diseases (PCVAD) that can severely impact domestic pig herds. For a non-enveloped virus with a small genome (1.7 kb ssDNA), PCV2 is remarkably diverse, with eight genotypes (a–h). New genotypes of PCV2 can spread through the migration of wild boar, which are thought to infect domestic pigs and spread further through the domestic pig trade. Despite a large swine population, the diversity of PCV2 genotypes in Ukraine has been under-sampled, with few PCV2 genome sequences reported in the past decade. To gain a deeper understanding of PCV2 genotype diversity in Ukraine, samples of blood serum were collected from wild boars (n = 107) that were hunted in Ukraine during the November–December 2012 hunting season. We found 34/107 (31.8%) prevalence of PCV2 by diagnostic PCR. For domestic pigs, liver samples (n = 16) were collected from a commercial market near Kharkiv in 2019, of which 6 out of 16 (37%) samples were positive for PCV2. We sequenced the genotyping locus ORF2, a gene encoding the PCV2 viral capsid (Cap), for 11 wild boar and six domestic pig samples in Ukraine using an Oxford Nanopore MinION device. Of 17 samples with resolved genotypes, the PCV2 genotype b was the most common in wild boar samples (10 out of 11, 91%), while the domestic pigs were infected with genotypes b and d. We also detected genotype b/d and b/a co-infections in wild boars and domestic pigs, respectively, and for the first time in Ukraine we detected genotype f in a wild boar from Poltava. Building a maximum-likelihood phylogeny, we identified a sublineage of PCV2 genotype b infections in both wild and domestic swine, suggesting a possible epizootic cluster and an ecological interaction between wild boar and domestic pig populations in northeastern Ukraine.

First Study to Describe the Prevalence of Porcine Reproductive and Respiratory Syndrome Virus and Porcine Circovirus Type 2 among the Farmed Pig Population in the Hong Kong Special Administrative Region.

Infection of pig farms with porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus type 2 (PCV2) causes substantial economic losses globally. However, little epidemiological data of PRRSV and PCV2 in the Hong Kong Special Administrative Region (HKSAR) were available. This pilot study aimed to provide baseline information of the prevalences of PPRSV and PCV2 in the HKSAR. A complex survey was conducted from 3 February 2020 to 11 March 2021 on 29 of the 40 pig farms in the HKSAR, with five pigs each from seven age groups (representing key production stages) tested using a real-time PCR. Evidence of presence of PRRSV European strain (PRRSV-1), PRRSV North American strain (PRRSV-2) and PCV2 was confirmed on 48%, 86% and 79% of farms, with overall prevalences of 7.6% (95% CI: 4.8–10.3%), 12.2% (95% CI: 9.6–14.7%) and 20.3% (95% CI: 14.3–26.2%) in the HKSAR pig population based on pooling results from all pigs across all farms. PRRSV-1 and PRRSV-2 were more prevalent in younger pigs, with the highest prevalences of 32.1% (95% CI: 20.8–45.0%) and 51.5% (95% CI: 38.9–64.0%) for 8-week-old pigs. In contrast, the distribution of PCV2 prevalence across age groups appeared to be more symmetrical, with higher prevalences reported in pigs from 12 weeks old to 24 weeks old but lower prevalences in younger pigs and sows. The results of this study demonstrate that PRRSV-1, PRRSV-2 and PCV2 are widely spread across pig farms in the HKSAR, which indicates that the current farm management and control protocols should be improved. We recommend the implementation of on-farm intervention strategies combined with ongoing surveillance to reduce these viruses, and their consequences, in the HKSAR pig population.

Genetic Diversity and Prevalence of Porcine Circovirus Type 2 in China During 2000-2019.

As the major pathogen for porcine circovirus-associated disease (PCVAD), porcine circovirus type 2 (PCV2) is no longer treated as an emerging virus anymore. The wide distribution of PCV2 infection in China causes huge economic losses in the swine industry. Currently, it is generally believed that PCV2 has eight genotypes (PCV2a to PCV2h), with PCV2a, PCV2b, and PCV2d being widely distributed. To comprehensively explore the genetic diversity and prevalence of PCV2 in China, PCV-2 sequences submitted from China in the GenBank database were retrieved. With a total of 714 PCV2 strains were retrieved, we found that early-submitted PCV2 sequences were mainly collected from coastal provinces in the southeast part of China, which may indicate PCV2 was initially circulating in those regions. From 2002 to 2008, PCV2b was the dominant prevalent genotype in those retrieved sequences. From 2009, PCV2d became the dominant genotype in those sequences, dropping a hint that a potential shift of PCV2b to PCV2d might occur in 2009, which is similar to the patterns at the global level. In addition to the PCV2a, PCV2b, and PCV2d genotypes, novel strains were also characterized. We further revealed that the amino acid sequences consistency of PCV2a Cap is higher than those in other genotypes. Together, this study provided clues for the possible prevalent genotypes and dynamics of genetic diversity in China from 2000 to 2019.

Correlations between lung pneumonic lesions and serologic status for key respiratory pathogens in slaughtered pigs in northern Uganda

BackgroundA cross-sectional study of slaughtered pigs was conducted in Lira district, Uganda, to (1) determine the prevalence and severity of pneumonia and (2) establish relationships between pneumonia types and the serological status for key respiratory pathogens. Using enzyme-linked immunosorbent assays (ELISAs), sera were screened for antibodies against Mycoplasma hyopneumoniae (M. hyo), Actinobacillus pleuropneumoniae (App), porcine reproductive and respiratory syndrome virus (PRRSv) and porcine circovirus type 2 (PCV2). Postmortem, lungs were grossly scored for pneumonia types and pneumonic lesions. Pneumonia types were characterized as catarrhal purulent bronchopneumonia (CPBP), pleuropneumonia (PLP) and pleuritis. The percent of lung surface affected by pneumonia was determined by estimating the affected surface area of each lung lobe. Each lobe was assigned scores based on the approximate volume represented and the total percentage of lung surface affected obtained as a sum of individual lobe scores. Metastrongylus spp. helminth infection was determined by examining lungs for gross presence or absence. RStudio was used for data analysis and presentation. Wilcoxon rank sum tests were used to compare median pneumonia lesion scores and serostatus for each studied pathogen. An ordinal logistic regression model was fitted to evaluate the odds of multiple pneumonia, with pathogen serostatus and Metastrongylus spp. infection as predictors.ResultsOne hundred sixty-seven (n = 167) lungs were examined for pneumonic lesions. The prevalences of CPBP, PLP and pleuritis were 29.9% (95% CI 22.9–36.9), 74.2% (95% CI 67.5–80.9) and 17.3% (95% CI 22.4–36.3), respectively. The true prevalence of PCV2 was 9.7% (95% CI 4.5–16.8), that of PRRSv was 7.5% (95% CI 2.7–14.2), that of M. hyo was 11.5% (95% CI 7.2–18.0), that of App was 25.1% (95% CI 18.5–38.0), and that of Metastrongylus spp. was 29.3% (95% CI 22.9–36.6). The odds of multiple pneumonia forms increased in pigs with multiple pathogens (ORs 2.6, p = 0.01) and Metastrongylus spp. infestation (OR 2.5, p = 0.003), suggesting synergistic effects of coinfections in the induction of lesions.ConclusionsThis study revealed a high prevalence and severity of pneumonic lesions in slaughtered pigs. It provides baseline information and evidence for the magnitude of pneumonia associated with the studied pathogens and justifies future studies on their potential economic impacts on Ugandan pigs.

Prevalence of Porcine Circovirus Type 2 (PCV-2) in Smallholder Pig Farms in Thung-Yai, Nakhon Si Thammarat, Thailand

Porcine circovirus type 2 (PCV2), which is a member of the Circovirus genus in the family of Circoviridae, is a small non-enveloped, closed-circular ssDNA. The PCV2-associated disease is one of the most important infectious agents on pig productivity worldwide, including China, India, Malaysia, and Thailand. It caused 2 major syndromes; postweaning multisystemic wasting syndrome (PMWS) and porcine dermatitis and nephropathy syndrome (PDNS). In addition, PCV2 may cause complexity with a pathogenic agent into porcine circovirus associated diseases (PCVADs). This study aimed to determine the prevalence of PCV2 in smallholder farms in Thung Yai district, Nakhon Si Thammarat, Thailand. A cross-sectional study was performed; 100 blood samples were collected from 13 smallholder pig farms. The samples were classified into 4 groups based on the pig’s age; gilts, 6 sows, nursery-to-starter, and from growing to finishing pigs. Blood samples were carried out for DNA +extraction and nested-PCR. The epidemiological study showed 9 % positive by genetic detection. The result suggested that growing-to-finishing pigs had significant PCV2 infection, followed by nursery-to-starter pigs and sow groups. In addition, multiple farms showed a high positive and significant correlation (Cr ≈ 0.245). These results reveal a low prevalence of PCV2 in endemic regions in southern Thailand, which may help in the local control evaluation and eradication programs. Furthermore, the phylogenic study of local strain should be investigated for the occurrence of PCV2 genetic evolution in Thailand and neighboring countries.

Prevalence of porcine circovirus 2 throughout China in 2015–2019: A systematic review and meta-analysis

Porcine circovirus type 2 (PCV2) causes infectious diseases in pigs leading to considerable economic losses in the pig industry. To prevent and control PCV2 infections, is important to understand the prevalence and geographical distribution of the virus. We performed the first systematic review and meta-analysis to estimate the prevalence of PCV2 in China. From PubMed, ScienceDirect, Chinese Web of Knowledge, Wanfang, and VIP Chinese Journal, we extracted 53 studies published in China between 2015 and 2019. There were 29,051 samples, 14,230 of which were positive for PCV2. The pooled prevalence of PCV2 was 46.0%, with the highest in Northeastern China (58.1%). The highest prevalence was 86.3% in Xinjiang province. Nursery pigs had the highest prevalence of PCV2 (50.9%), and the serological test detected the highest number of cases (58.5%). PCV2 prevalence was 50.1% in intensive farms and 37.5% in extensive farms. Our findings showed that PCV2 is common throughout China. Effective control measures are necessary to reduce PCV2 infections.

Efficacy in pigs of a new inactivated vaccine combining porcine circovirus type 2 and Mycoplasma hyorhinis

Coinfection with porcine circovirus type 2 (PCV2) and Mycoplasma hyorhinis (Mhr) can induce more-severe disease than a single infection with either. We evaluated the efficacy of a new vaccine combining inactivated PCV2 and Mhr, in a model of PCV2 and Mhr infection. Twenty-five 35-day-old PCV2- and Mhr-free pigs were randomly divided into five groups, with five pigs in each group. The pigs in groups 1 and 2 were vaccinated with the combined vaccine and then challenged with Mhr or PCV2, respectively. The pigs in groups 3 and 4 were not vaccinated and then challenged with PCV2 or Mhr, respectively, and group 5 was used as the unvaccinated unchallenged control. Two weeks after booster immunization via the intramuscular route, all the pigs except those in control group 5 were challenged with PCV2 or Mhr. All the pigs were euthanized 28 days after challenge. The pigs in vaccinated groups 1 and 2 showed a significant increase in weight after challenge with PCV2 or Mhr (P < 0.001), with an average daily gain (ADG) of 0.315 kg compared with unvaccinated groups 3 and 4 (0.279 kg). Mhr was isolated from the unvaccinated pig lungs after Mhr challenge, whereas it was not isolated from the vaccinated pigs. No PCV2 or Mhr was detected with PCR or histochemical staining in vaccinated groups 1 and 2. A statistical analysis showed that the PCV2 and Mhr combined vaccine providing protected against PCV2 infection causing viremia and inguinal lymphadenopathy (5 pigs protected out 5) or against Mhr infection causing fiber inflammation (4 pigs out 5). Thus, we have developed an effective combined vaccine for the prevention and control of PCV2 or Mhr infections in swine herds, this will help reduce prevalence of PCV2 and Mhr coinfections.

Phylogenetic analysis of porcine circovirus type 2 (PCV2) between 2015 and 2018 in Henan Province, China

BackgroundPorcine circovirus type 2 (PCV2) is the pathogen of porcine circovirus associated diseases (PCVAD) and one of the main pathogens in the global pig industry, which has brought huge economic losses to the pig industry. In recent years, there has been limited research on the prevalence of PCV2 in Henan Province. This study investigated the genotype and evolution of PCV2 in this area.ResultsWe collected 117 clinical samples from different regions of Henan Province from 2015 to 2018. Here, we found that the PCV2 infection rate of PCV2 was 62.4%. Thirty-seven positive clinical samples were selected to amplify the complete genome of PCV2 and were sequenced. Based on the phylogenetic analysis of PCV2 ORF2 and complete genome, it was found that the 37 newly detected strains belonged to PCV2a (3 of 37), PCV2b (21 of 37) and PCV2d (13 of 37), indicating the predominant prevalence of PCV2b and PCV2d strains. In addition, we compared the amino acid sequences and found several amino acid mutation sites among different genotypes. Furthermore, the results of selective pressure analysis showed that there were 5 positive selection sites.ConclusionsThis study indicated the genetic diversity, molecular epidemiology and evolution of PCV2 genotypes in Henan Province during 2015–2018.

Real-Time PCR Detection Patterns of Porcine Circovirus Type 2 (PCV2) in Polish Farms with Different Statuses of Vaccination against PCV2.

Porcine circovirus type 2 (PCV2) is a globally spread pathogen controlled with generally highly efficacious vaccination protocols. In order to compare PCV2 detection profiles in farms with different vaccination statuses, serum (359) and fecal pools (351) and oral fluids (209) from four farms that do not vaccinate against PCV2 (NON-VAC) and from 22 farms that do vaccinate (VAC) were tested with quantitative real-time PCR. Additionally, nucleotide sequences of ORF2 of the virus were obtained from selected samples. Three genotypes, PCV2a, PCV2b, and PCV2d, were detected. Significant differences (p < 0.05) in PCV2 prevalence and quantities between the VAC and NON-VAC farms were evident. In five VAC farms, no viremia or shedding in feces was detected. On the other hand, in four VAC farms, the results were very similar to those from NON-VAC farms. No significant difference in PCV2 prevalence in oral fluids was observed between VAC and NON-VAC farms. An examination of viremia can be recommended for the detection of vaccination efficacy issues. The median of the PCV2 viral loads >6.0 log10 copies/mL in pooled sera from the vaccinated population should be considered a very strong indication that the vaccination protocol needs revision.

Changes on the viral capsid surface during the evolution of porcine circovirus type 2 (PCV2) from 2009 till 2018 may lead to a better receptor binding.

Porcine circovirus type 2 (PCV2) is the primary causative agent of porcine circovirus-associated diseases (PCVAD). Three major PCV2 genotypes (PCV2a, PCV2b, and PCV2d) have been identified globally. Despite their worldwide distribution, the prevalence and genetic evolution of PCV2 in Belgium has not previously been determined. In this study, 319 samples from animals suffering from diseases likely to be associated with PCV2 were collected from 2009 to 2018 and analysed by virus titration. The overall prevalence of PCV2 in PCVAD-suspected cases was 15.7 per cent (50/319). The phylogenetic analysis demonstrated that at least three genotypes (PCV2a, PCV2b, and PCV2d) circulated in Belgium from 2009 till 2018, and that PCV2 evolved from PCV2a to PCV2b and from PCV2d-1 to PCV2d-2. Sequence comparison among the forty-three PCV2 isolates showed that they had 89.7–100 per cent nucleotide-sequence and 88.5–100 per cent amino-acid-sequence identities. Three amino acid sites were under positive selection. Three-dimensional analysis of genotype-specific amino acids revealed that most of the mutations were on the outside of the cap protein with a few conserved mutations present on the inner side. Mutations toward more basic amino acids were found on the upper and tail parts of two connecting capsid proteins which form one big contact region, most probably involved in receptor binding. The lower part was relatively conserved. This polarity change together with the formation of an extruding part drive the virus to a more efficient GAG receptor binding. Taken together, these results showed a genotype shift from PCV2a to PCV2b and later on from PCV2d-1 to PCV2d-2, and a PCV2 evolution toward a better receptor binding capacity.

Seroprevalence of PCV2 in north eastern hill states of India

This study describe the seroprevalence of porcine circovirus type 2 (PCV2) in north eastern hill (NEH) states of India. Information on PCV2 from NEH states is lacking. Serum samples (306) were collected from the pigs and different epidemiological parameters like age, sex, and litter size of drift or sounder, system of rearing and different clinical symptoms from November 2017 to May 2018. Samples were screened for PCV2 infection by commercially available ELISA kit (INGEZIM PCV IgG and INGEZIM PCV IgM, Ingenasa, Madrid, Spain). Out of 306 serum samples tested, 151 samples were positive for PCV2 infection. An overall PCV2 prevalence of 49.35% was recorded in NEH states of India. Highest prevalence was found in Sikkim (94%) and lowest prevalence in Nagaland (4%). This study revealed that PCV2 is prevalent in all the north eastern states of India which necessitates the need for implementation of prevention and control measures.

The prevalence of PCV2 viremia in newborn piglets on four endemically infected Dutch sow farms is very low

Porcine circovirus type 2 (PCV2) systemic disease is currently considered one of the most relevant infectious diseases in swine industry worldwide from an economical point of view. Although piglets generally become diseased between 8 and 16 weeks of age, they can be infected much earlier, even already in utero. However, data on the prevalence of PCV2 infection in newborn piglets are very variable (lower than 40 up to 82%) and most of the studies have been performed in US. In European pig farms, using group-housing systems for gestating sows, a different herd PCV2 infection and immunological status may be expected and was recently reported in Germany. If that is the current scenario in most European farms, strategies to prevent horizontal transmission become essential for the control of the infection.The aim of our study was to determine the PCV2 prevalence in newborn piglets on 4 endemically infected farms in the Netherlands under European conditions. Eleven sows and 8 piglets per litter from 4 farms selected by their assumed PCV2 endemic infection status were sampled. Plasma from piglets was analysed with a PCV2 qPCR and serum from the sows was analysed with a commercial circovirus IgG ELSIA, circovirus IgM ELISA and PCV2 qPCR. In none of the samples from the piglets PCV2 was detected by the qPCR. None of the samples from the sows tested positive in the qPCR and circovirus IgM ELISA. The true- and apparent prevalence of IgG at herd and sow level were 0.75 and 0.81 and, 0.30 and 0.32, respectively, and no statistically significant association with sow parity was observed. These results reveal a very low prevalence of PCV2 in newborn piglets on endemically infected farms in The Netherlands, opening the opportunity of re-evaluation of the control measures applied in these farms.

Phylogenetic analysis of two goat-origin PCV2 isolates in China

Complete genome characterization of non-porcine origin Porcine circovirus type 2 (PCV2) was first described in 2014 in China. In the present study, we first identified PCV2 nucleotides in goat samples and the prevalence of PCV2 in goat was 6.15%. However, only two new strains, Goat2014-4 and Goat2014-5, could be completely sequenced. The genome of the strain Goat2014-4, which collected from the goat infected with PPRV, contains 1766 nt; strain Goat2014-5, which originated from a healthy goat, is comprised of 1767 nt. The results showed that they shared the highest nucleotide identity with BDH and the lowest similarity with DK1980PMWSfree strain and they belonged only to genotype PCV2d. Meanwhile, they shared higher homology with porcine-origin PCV2 strains than others. Moreover, a detailed analysis of the capsid amino acid sequences revealed that there were distinct differences for goat2014-4 (708 bp) and goat2014-5 (705 bp); strain Goat2014-4 showed an elongation of two amino acids, and strains Goat2014-5 showed an elongation of one amino acid compared with other reference strains. This is the first report of the genetic analysis of goat-origin PCV2 isolates. It also provides an additional supported evidence for cross-species transmission of PCV2.

Retrospective study of porcine circovirus type 2 infection reveals a novel genotype PCV2f.

Porcine postweaning multisystemic wasting syndrome (PMWS) caused by porcine circovirus type 2 (PCV2) is a disease causing severe economic losses annually worldwide to the pig industry. PCV2 infection was first reported in China in 2000, and currently has three major genotypes, PCV2a, b and d, circulating in this country. To further elucidate the origin and prevalence of PCV2 in China, 123 clinical pig tissue samples collected in 25 provinces between 1990 and 1999 were analysed by PCV2-specific PCR, resulting in identification of 23 PCV2 strains collected between 1996 and 1999. Phylogenetic analysis based on the nucleotide sequences of open reading frame 2 (ORF2) showed that 20 of the 23 grouped within PCV2a, while the remaining three strains formed an independent clade, so far unreported and therefore named PCV2f. This genotype shared lower sequence identity with other known genotypes. This study provides further understanding of the genetic diversity and evolution of PCV2 and has tracked PCV2 infection in China back to 1996 rather than 2000.