Implications of Cross-Reactivity and Cross-Protection for Pneumococcal Vaccine Development.

Pneumococcal vaccines are a cornerstone for the prevention of pneumococcal diseases, reducing morbidity and mortality in children and adults worldwide. Pneumococcal vaccine composition is based on the polysaccharide capsule of Streptococcus pneumoniae, which is one of the most important identified contributors to the pathogen's virulence. Similarities in the structural composition of polysaccharides included in licensed pneumococcal vaccines may result in cross-reactivity of immune response against closely related serotypes, including serotypes not included in the vaccine. Therefore, it is important to understand whether cross-reactive antibodies offer clinical protection against pneumococcal disease. This review explores available evidence of cross-reactivity and cross-protection associated with pneumococcal vaccines, the challenges associated with the assessment of cross-reactivity and cross-protection, and implications for vaccine design and development.

Post-SARS-CoV-2 infection and post-vaccine-related neurological complications share clinical features and the same positivity to anti-ACE2 antibodies.

Introduction: A potential overlap in symptoms between post-acute COVID-19 syndrome and post-COVID-19 vaccination syndrome has been noted. We report a paired description of patients presenting with similar manifestations involving the central (CNS) or peripheral nervous system (PNS) following SARS-CoV-2 infection or vaccination, suggesting that both may have triggered similar immune-mediated neurological disorders in the presence of anti-idiotype antibodies directed against the ACE2 protein. Patients and methods: Four patients exhibited overlapping neurological manifestations following SARS-CoV-2 infection or vaccination: radiculitis, Guillain-Barré syndrome, and MRI-negative myelitis, respectively, sharing positivity for anti-ACE2 antibodies. Autoantibodies against AQP-4, MOG, GlyR, GAD, and amphiphysin, onconeural antibodies for CNS syndromes, and anti-ganglioside antibodies for PNS syndromes tested negative in all patients. Discussion: Anti-idiotype antibodies against ACE2 have been detected in patients who recovered from COVID-19 infection, and it has been hypothesized that such antibodies may mediate adverse events following SARS-CoV-2 infection or vaccination, resulting in the activation of the immune system against cells expressing ACE2, such as neurons. Our data reveal clinically overlapping syndromes triggered by SARS-CoV-2 infection or vaccination, sharing positivity for anti-ACE2 antibodies. Their presence, in the absence of other classic autoimmune markers of CNS or PNS involvement, suggests that they might play an active role in the context of an aberrant immune response. Conclusion: Anti-idiotype antibodies directed against ACE2 may be triggered by both SARS-CoV-2 infection and vaccination, possibly contributing to neurological autoimmune manifestations. Their pathogenic role, however, remains to be demonstrated in large-scale, more structured studies.

High serum prevalence of autoreactive IgG antibodies against peripheral nerve structures in patients with neurological post-COVID-19 vaccination syndrome.

Background: Patients suffering from neurological symptoms after COVID-19 vaccination (post-COVID-19 vaccination syndrome (PCVS)) have imposed an increasing challenge on medical practice, as diagnostic precision and therapeutic options are lacking. Underlying autoimmune dysfunctions, including autoantibodies, have been discussed in neurological disorders after SARS-CoV-2 infection and vaccination. Here, we describe the frequency and targets of autoantibodies against peripheral nervous system tissues in PCVS. Methods: Sera from 50 PCVS patients with peripheral neurological symptoms after COVID-19 vaccination and 35 vaccinated healthy controls were used in this study. IgG autoreactivity was measured via indirect immunofluorescence assays on mouse sciatic nerve teased fibers. The frequencies of autoantibodies were compared between groups using Fisher's exact test. Serum anti-ganglioside antibodies were measured in ganglioside blots. Autoantibody target identification was performed using immunoprecipitation coupled to mass spectrometry. Subsequent target confirmation was conducted via cell-based assays and ELISA. Results: Compared with controls, PCVS patients had a significantly greater frequency of autoantibodies against peripheral nervous system structures (9/50(18%) vs 1/35(3%); p=0.04). Autoantibodies bound to paranodes (n=5), axons (n=4), Schmidt-Lanterman incisures (n=2) and Schwann cell nuclei (n=1). Conversely, antibodies against gangliosides were absent in PCVS patients. Target identification and subsequent confirmation revealed various subunits of neurofilaments as well as DFS-70 as autoantibody epitopes. Conclusion: Our data suggest that autoantibodies against nervous system tissue could be relevant in PCVS patients. Autoantibodies against neurofilaments and cell nuclei with so far non-established links to this disease spectrum should be further elucidated to determine their biomarker potential.

Surveillance of invasive pneumococcal disease in Spain exploring the impact of the COVID-19 pandemic (2019-2023).

OBJECTIVES: Dynamic trends of invasive pneumococcal disease (IPD) including the evolution of prevalent serotypes are very useful to evaluate the impact of current and future pneumococcal conjugate vaccines (PCVs) and the rise of non-vaccine serotypes. In this study, we include epidemiological patterns of S. pneumoniae before and after COVID-19 pandemic. METHODS: We characterized all national IPD isolates from children and adults received at the Spanish Pneumococcal Reference Laboratory during 2019-2023. RESULTS: In the first pandemic year 2020, we found a general reduction in IPD cases across all age groups, followed by a partial resurgence in children in 2021 but not in adults. By 2022, IPD cases in children had returned to pre-pandemic levels, and partially in adults. In 2023, IPD rates surpassed those of the last pre-pandemic year. Notably, the emergence of serotype 3 is of significant concern, becoming the leading cause of IPD in both pediatric and adult populations over the last two years (2022-2023). Increase of serotype 4 in young adults occurred in the last epidemiological years. CONCLUSIONS: The COVID-19 pandemic led to a temporary decline in all IPD cases during 2020 attributable to non-pharmaceutical interventions followed by a subsequent rise. Employing PCVs with broader coverage and/or enhanced immunogenicity may be critical to mitigate the marked increase of IPD.

Immunogenicity of Current and Next-Generation Pneumococcal Conjugate Vaccines in Children: Current Challenges and Upcoming Opportunities.

Global use of pneumococcal conjugate vaccines (PCVs) with increasingly broader serotype coverage has helped to reduce the burden of pneumococcal disease in children and adults. In clinical studies comparing PCVs, higher-valency PCVs have met noninferiority criteria (based on immunoglobulin G geometric mean concentrations and response rates) for most shared serotypes. A numeric trend of declining immunogenicity against shared serotypes with higher-valency PCVs has also been observed; however, the clinical relevance is uncertain, warranting additional research to evaluate the effectiveness of new vaccines. Novel conjugation processes, carriers, adjuvants, and vaccine platforms are approaches that could help maintain or improve immunogenicity and subsequent vaccine effectiveness while achieving broader protection with increasing valency in pneumococcal vaccines.

Epizootiological surveillance of porcine circoviruses in free-ranging wild boars in China.

Four species of porcine circoviruses (PCV1-4) have been reported to circulate in Chinese domestic pigs, while the epizootiology of these viruses in free-ranging wild boars in China remains unknown. In this study, tissue and serum samples collected from diseased or apparently healthy wild boars between 2018 and 2020 in 19 regions of China were tested for the prevalence of PCV1-4 infections. Positive rates of PCV1, PCV2, and PCV3 DNA in the tissue samples of Chinese wild boars were 1.6% (4/247), 58.3% (144/247), and 10.9% (27/247) respectively, with none positive for PCV4. Sequence analysis of viral genome showed that the four PCV1 strains distributed in Hunan and Inner Mongolia shared 97.5%-99.6% sequence identity with global distributed reference strains. Comparison of the ORF2 gene sequences showed that 80 PCV2 strains widely distributed in 18 regions shared 79.5%-100% sequence identity with reference strains from domestic pigs and wild boars, and were grouped into PCV2a (7), PCV2b (31) and PCV2d (42). For PCV3, 17 sequenced strains shared 97.2%-100% nucleotide identity at the genomic level and could be divided into PCV3a (3), PCV3b (2) and PCV3c (12) based on the phylogeny of ORF2 gene sequences. Serological data revealed antibody positive rates against PCV1 and PCV2 of 11.4% (19/167) and 53.9% (90/167) respectively. The data obtained in this study improved our understanding about the epidemiological situations of PCVs infection in free-ranging wild boars in China and will be valuable for the prevention and control of diseases caused by PCVs infection.

Spread of multidrug resistance in non-PCV13/PCV20 serotypes of Streptococcus pneumoniae: A cross-sectional study ten years after the introduction of pneumococcal conjugate vaccine in Japan.

Ten years after the introduction of the pneumococcal conjugate vaccine (PCV) in Japan, the prevalence rates of non-PCV13 and non-PCV20 serotypes among pediatric pneumococcal isolates were 94.0% and 73.7%, respectively. The predominant non-PCV13/PCV20 serotypes (15A, 35B, and 23A) were mostly multidrug-resistant (≥80.5%), exhibiting non-susceptibility to penicillin.

COVID-19, post-acute COVID-19 syndrome (PACS, "long COVID") and post-COVID-19 vaccination syndrome (PCVS, "post-COVIDvac-syndrome"): Similarities and differences.

Worldwide there have been over 760 million confirmed coronavirus disease 2019 (COVID-19) cases, and over 13 billion COVID-19 vaccine doses have been administered as of April 2023, according to the World Health Organization. An infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can lead to an acute disease, i.e. COVID-19, but also to a post-acute COVID-19 syndrome (PACS, "long COVID"). Currently, the side effects of COVID-19 vaccines are increasingly being noted and studied. Here, we summarise the currently available indications and discuss our conclusions that (i) these side effects have specific similarities and differences to acute COVID-19 and PACS, that (ii) a new term should be used to refer to these side effects (post-COVID-19 vaccination syndrome, PCVS, colloquially "post-COVIDvac-syndrome"), and that (iii) there is a need to distinguish between acute COVID-19 vaccination syndrome (ACVS) and post-acute COVID-19 vaccination syndrome (PACVS) - in analogy to acute COVID-19 and PACS ("long COVID"). Moreover, we address mixed forms of disease caused by natural SARS-CoV-2 infection and COVID-19 vaccination. We explain why it is important for medical diagnosis, care and research to use the new terms (PCVS, ACVS and PACVS) in order to avoid confusion and misinterpretation of the underlying causes of disease and to enable optimal medical therapy. We do not recommend to use the term "Post-Vac-Syndrome" as it is imprecise. The article also serves to address the current problem of "medical gaslighting" in relation to PACS and PCVS by raising awareness among the medical professionals and supplying appropriate terminology for disease.

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

A number of disorders that harm pig production are linked to porcine circoviruses, including PCV2. PCV2 infection is a substantial contributor to porcine-circovirus-associated illnesses (PCAS) and the post-weaning multi-systemic wasting syndrome (PMWS), which have a significant negative economic impact on pig production. Additionally, PCV infection has been labeled as a global concern to cattle and wildlife. This study's objectives were to examine the prevalence of PCV1/2/3 in Jiangxi Province, China, and to clarify the epidemiological significance of wild boar in PCV epidemiology. The 2020 hunting seasons resulted in the collection of 138 wild boar samples for PCV1/2/3 detection, which was followed by the genetic clarification of PCV2 strains. According to our data, 21.7% (30/138) of the population had PCV1 positivity, 22.5% (31/138) had PCV2 positivity, and 5.8% (8/138) had PCV3 positivity. Additionally, 10 out of 138 wild boar samples had PCV1 and PCV2 co-infections, while 5 out of 138 wild boar samples had PCV2 and PC3 co-infections. Nineteen full-length PCV2 genomes measuring 1767 nt were recovered from various animal tissues using conventional PCR. Eighteen out of nineteen PCV2 strains were identified as PCV2b by phylogenetic tree analysis, which was completed by the reference strain HLJ2015 obtained from domestic pigs in 2015. Additionally, one genotype of PCV2d JX11-2020 (MW889021) shared a sub-branch with the referenced strain TJ (AY181946), which was isolated in domestic pigs in 2002. This finding raises the possibility that domestic pigs could contract PCV2 strains from wild boar, posing a serious threat to the Jiangxi province of China's pig production industry.

The Prevalence and Genetic Diversity of PCV3 and PCV2 in Colombia and PCV4 Survey during 2015-2016 and 2018-2019.

Four genotypes of circovirus have been recognized in swine, with PCV2 and PCV3 being the most associated with clinical manifestations, while PCV4 does not have a defined disease. In addition, PCV2 is associated with different syndromes grouped as diseases associated with porcine circovirus (PCVAD), while PCV3 causes systemic and reproductive diseases. In the present study, we retrospectively detected PCV2, PCV3, and PCV4 in Colombia during two periods: A (2015-2016) and B (2018-2019). During period A, we evaluated stool pools from the 32 Colombian provinces, finding a higher prevalence of PCV3 compared to PCV2 as well as PCV2/PCV3 co-infection. Furthermore, we determined that PCV3 had been circulating since 2015 in Colombia. Regarding period B, we evaluated sera pools and tissues from abortions and stillborn piglets from the five provinces with the highest pig production. The highest prevalence found was for PCV3 in tissues followed by sera pools, while PCV2 was lower and only in sera pools. In addition, PCV2/PCV3 co-infection in sera pools was also found for this period. The complete genome sequences of PCV3 and PCV3-ORF2 placed the Colombian isolates within clade 1 as the majority in the world. For PCV2, the predominant genotype currently in Colombia is PCV2d. Likewise, in some PCV3-ORF2 sequences, a mutation (A24V) was found at the level of the Cap protein, which could be involved in PCV3 immunogenic recognition. Regarding PCV4, retrospective surveillance showed that there is no evidence of the presence of this virus in Colombia.

International links between Streptococcus pneumoniae vaccine serotype 4 sequence type (ST) 801 in Northern European shipyard outbreaks of invasive pneumococcal disease.

BACKGROUND: Pneumococcal disease outbreaks of vaccine preventable serotype 4 sequence type (ST)801 in shipyards have been reported in several countries. We aimed to use genomics to establish any international links between them. METHODS: Sequence data from ST801-related outbreak isolates from Norway (n = 17), Finland (n = 11) and Northern Ireland (n = 2) were combined with invasive pneumococcal disease surveillance from the respective countries, and ST801-related genomes from an international collection (n = 41 of > 40,000), totalling 106 genomes. Raw data were mapped and recombination excluded before phylogenetic dating. RESULTS: Outbreak isolates were relatively diverse, with up to 100 SNPs (single nucleotide polymorphisms) and a common ancestor estimated around the year 2000. However, 19 Norwegian and Finnish isolates were nearly indistinguishable (0-2 SNPs) with the common ancestor dated around 2017. CONCLUSION: The total diversity of ST801 within the outbreaks could not be explained by recent transmission alone, suggesting that harsh environmental and associated living conditions reported in the shipyards may facilitate invasion of colonising pneumococci. However, near identical strains in the Norwegian and Finnish outbreaks does suggest that transmission between international shipyards also contributed to those outbreaks. This indicates the need for improved preventative measures in this working population including pneumococcal vaccination.

Prevalence of Pneumococcal Carriage among Jordanian Infants in the First 6 Months of Age, 2008-2016.

BACKGROUND: Streptococcus pneumoniae is an opportunistic human-adapted pathogen driven by nasopharyngeal carriage. AIMS: To find the pneumococcal carriage rate, resistance, serotypes, and coverage of pneumococcal conjugate vaccines (PCVs) among infants in the first six months of age in the period from March 2008 to April 2016. METHODS: Nasopharyngeal swabs (NP) were taken from healthy infants from the northern part of Jordan. Swabs were processed for cultivation, identification, resistance testing and serotyping according to standard methods. RESULTS: During the surveillance period, 484 infants of this age group were tested, with a total carriage rate of 56.2%. 96.2% of infants one to two months of age got one PCV7 injection and were 58% carriers at the time of the first injection. At age three to four months, 84.9% had received two injections, with a carriage rate of 54.9% at the time of the second injection. At ages five to six months, 12.5% had received one to three injections, with a carriage rate of 43.8%. Predominant serotypes in all age groups were 19F (12.5%), 6A (11.4%), 11A (8.4%), 19A (7.0%), 6B (6.6%), 23F (5.9%), 15B (5.1%), 15A and 23A (4.0% each). Coverage of PCV7, PCV13 and the future PCV20 among all cases were 30.5%, 50.7% and 70.6%, respectively. The highest coverage rate of 78.6% was noticed in the age group at five to six months with the future PCV20. Antibiotic resistance was the highest in the first age group. CONCLUSIONS: Pneumococcal carriage starts from the first month of the infant's life. The highest coverage was noticed for PCV20, which implies the necessity for inoculation with future vaccines.

Serotypes in Adult Pneumococcal Pneumonia in Spain in the Era of Conjugate Vaccines.

We studied changes in serotype distribution and antimicrobial susceptibility in adult pneumococcal pneumonia in Spain (2011-2019). Among 895 pneumococci collected (433 bacteremic [BPP] and 462 non-bacteremic [non-BPP]), serotypes 3 (17%), 19A (10%), 8 (6.7%) and 11A (6.7%) were the most frequent. Serotypes 16F, 19A and 24F were associated with old people (≥65) and serotypes 4, 7F, 8, 12F and 19F to young adults. Serotypes 12F, 24F and 1 were significantly more frequent in BPP and serotypes 11A, 23A and 19F in non-BPP. Amoxicillin resistance was higher in non-BPP (17% vs. 11%) while penicillin non-susceptibility (37% vs. 24%) and macrolide resistance (29% vs. 14%) were higher in older adults. In the period 2017-2019, the vaccine coverages were: 32% (PCV13), 39% (PCV15), 65% (PCV20) and 69% (PPV23). Differences were found in serotype composition and antimicrobial resistance by age and type of infection. The maintenance of serotype 3 as a leading cause of adult pneumococcal pneumonia and the increase in highly invasive (serotype 8) or antimicrobial-resistant (serotype 11A) serotypes is worrisome. Further studies will be required to analyse the impact of the upcoming broader conjugate vaccines.

Urban and Rural Disparities in Pneumococcal Carriage and Resistance in Jordanian Children, 2015-2019.

BACKGROUND: A pneumococcal carriage surveillance study took place examining Jordanian children in urban and rural areas in the period 2015-2019. OBJECTIVES: To determine urban and rural differences in pneumococcal carriage rate, resistance, and serotypes among healthy Jordanian children from Amman (urban) and eastern Madaba (rural). METHODS: Nasopharyngeal swabs (NP) were taken from 682 children aged 1 to 163 months. Pneumococcal identification, serotyping, and resistance were performed according to standard method. RESULTS: The number of cases tested for Amman was 267 and there were 415 cases tested for eastern Madaba. Carriage rate for eastern Madaba was 39.5% and 31.1% for Amman. Predominant serotypes for eastern Madaba and Amman were 19F (21.3%; 15.7%), 23F (12.2%; 9.6%), 14 (6.7%; 2.4%), 19A (4.9%; 2.4%), and 6A (5.5%; 3.6%). Resistance rates for eastern Madaba and Amman were as follows: penicillin (95.8%; 81.9%), clarithromycin (68.9%; 59.0%), clindamycin (40.8%; 31.3%), and trimethoprim-sulfamethoxazole (73.2%; 61.4%). Coverage of PCV7, PCV13, and the future PCV20 for Amman was 42.2%, 48.2%, and 60.2%; for eastern Madaba, coverage was 50.0%, 62.2%, and 73.2%, respectively. In Amman 25.8% of children received 1-3 PCV7 injections compared to 1.9% of children in eastern Madaba. CONCLUSIONS: There were significant differences in carriage, resistance, and coverage between both regions. The potential inclusion of a PCV vaccination program for rural areas is essential.

What do we know about porcine circovirus 3 (PCV3) diagnosis so far?: A review.

Porcine circovirus 3 (PCV3) was first discovered in 2016, almost concomitantly by two groups of researchers in the United States. The novel case was reported in a group of sows with chronic reproductive problems with clinical presentation alike porcine dermatitis and nephropathy syndrome (PDNS), where metagenomic sequencing revealed a genetically divergent porcine circovirus designated PCV3. The discovery of PCV3 in a PDNS case, which used to be considered as part of PCVAD attributed to PCV2 (porcine circovirus 2), has garnered attention and effort in further research of the novel virus. Just when an infectious molecular DNA clone of PCV3 has been developed and successfully used in an in vivo pathogenicity study, yet another novel PCV strain surfaced, designated PCV4 (porcine circovirus 4). So far, PCV3 has been reported in domestic swine population globally at low to moderate prevalence, from almost all sample types including organ tissues, faecal, semen and colostrum samples. PCV3 has been associated with a myriad of clinical presentations, from PDNS to porcine respiratory disease complex (PRDC). This review paper summarizes the studies on PCV3 to date, with focus on diagnosis.

The Impact of Pneumococcal Conjugate Vaccine (PCV) Coverage Heterogeneities on the Changing Epidemiology of Invasive Pneumococcal Disease in Switzerland, 2005-2019.

Pneumococcal conjugate vaccines (PCVs) have lowered the incidence of invasive pneumococcal disease (IPD) worldwide. However, the influence of regional vaccine uptake differences on the changing epidemiology of IPD remains unclear. We aimed to examine the overall impact of both seven- and 13-valent PCVs (PCV7 and PCV13) on IPD in Switzerland. Three-year periods from 2005-2010 and 2011-2019 were considered, respectively, as (early and late) PCV7 eras and (early, mid and late) PCV13 eras. Vaccine coverage was estimated from a nationwide survey according to east (German-speaking) and west (French/Italian-speaking) regions for each period. Reported incidence rate ratios (IRRs) were compared between successive periods and regions using nationwide IPD surveillance data. Overall IPD incidence across all ages was only 16% lower in the late PCV13 era compared to the early PCV7 era (IRR 0.83, 95% CI 0.79-0.88), due to increasing incidence of non-PCV-type IPD (2.59, 2.37-2.83) in all age groups, except children <5 years. PCV uptake rates in swiss children were slightly higher in the west than the east (p < 0.001), and were accompanied by lower IPD incidences across all age groups in the former region. Post-PCV13, non-PCV serotypes 8, 22F and 9N were the major cause of IPD in adults ≥65 years. Increased PCV coverage in both areas of Switzerland resulted in a decrease in vaccine-type and overall IPD incidence across all age groups, in a regionally dependent manner. However, the rising incidence of non-vaccine-type IPD, exclusive to older adults, may undermine indirect beneficial effects.

Twenty-Year Public Health Impact of 7- and 13-Valent Pneumococcal Conjugate Vaccines in US Children.

Pneumococcal conjugate vaccines (PCVs) have been used in the United States since 2000. To assess the cumulative 20-year effect of PCVs on invasive pneumococcal disease (IPD) incidence among children <5 years of age, we analyzed Active Bacterial Core Surveillance data, conducted a literature review, and modeled expected and observed disease. We found that PCVs have averted >282,000 cases of IPD, including ≈16,000 meningitis, ≈172,000 bacteremia, and ≈55,000 bacteremic pneumonia cases. In addition, vaccination has prevented 97 million healthcare visits for otitis media, 438,914-706,345 hospitalizations for pneumonia, and 2,780 total deaths. IPD cases declined 91%, from 15,707 in 1997 to 1,382 in 2019. Average annual visits for otitis media declined 41%, from 78 visits/100 children before PCV introduction to 46 visits/100 children after PCV13 introduction. Annual pneumonia hospitalizations declined 66%-79%, from 110,000-175,000 in 1997 to 37,000 in 2019. These findings confirm the substantial benefits of PCVs for preventing IPD in children.

Vaccines against antimicrobial resistance: a promising escape route for multidrug resistance.

Antibiotic resistance has become a global health problem requiring urgent intervention. The pace of development and frequency of transmission of antimicrobial resistance have tremendously surpassed the number of antibiotics developed in the past few decades. Emergence and transmission of multidrug-resistant genes, for example, mcr-1 and mcr-5.3, against the last resort of antibiotics has challenged the treatment options. Vaccination is a promising approach with no instance of antimicrobial resistance generation or transmission reported so far. The time required for developing a vaccine, extensive pre- and post-licensure studies and the financial constraints for the R&D has hampered vaccine development over the past few decades. Vaccine can prove to be an effective future strategy for combating antimicrobial resistance.

Development and application of a quadruplex real-time PCR assay for differential detection of porcine circoviruses (PCV1 to PCV4) in Jiangsu province of China from 2016 to 2020.

To date, four species of porcine circoviruses (PCVs), including PCV1-4, have been reported to exist in the clinical cases. Fast and effective differential detection is critical to monitor the infection and co-infection status of PCVs for adopting reliable control strategies. However, currently available methods cannot simultaneously differentiate the four species of PCV strains. In this study, a quadruplex real-time PCR assay based on TaqMan probes was developed for differential detection of PCV1-4. The new quadruplex real-time PCR assay exhibited satisfied specificity, sensitivity, repeatability and reproducibility. In addition, the new assay was applied to the detection of 120 clinical samples collected from 2016 to 2020 in Jiangsu province of China and compared with previously reported PCV1-4 singleplex conventional PCR assays. Based on the clinical performance, the results from the quadruplex real-time PCR and conventional PCR assays showed 100% agreement. A total of 47 samples were detected as PCV positive by the quadruplex real-time PCR assay, including 1, 2, 1 samples were co-infected with PCV1 and PCV4, PCV2 and PCV3, PCV2 and PCV4, respectively. Full-length ORF2 sequencing and phylogenetic analysis supported the real-time PCR results that 5, 34, 8 and 4 of the 51 PCV sequences were PCV1, PCV2, PCV3 and PCV4, respectively. This study provides a promising alternative tool for rapid differential detection of PCVs and confirms the coexistence of all species of PCV1-4 strains in Jiangsu province in recent years.