Does porcine circovirus type 3 (PCV3) interfere with porcine circovirus type 2 (PCV2) vaccine efficacy?

Abstract

PCV2 is globally spread pathogen involved in a number of diseases (PCVD). Commonly used vaccines against PCV2 are proved to be highly efficacious. The role of recently discovered PCV3 for pig health and interference with PCV2 remains unknown. The study performed on serum samples from seven farms vaccinated against PCV2 and four non-vaccinated showed very low prevalence of PCV2 viremia in the former (3 out of 106 positive serum pools) and high prevalence of PCV2 viremia in the latter (35 out of 60 positive pools). Mean log 10 PCV2 genome equivalents were lower in vaccinated farms (4.8 ± 0.6 log 10 copies/ml) than in non-vaccinated farms (6.3 ± 1.3 log 10 copies/ ml). PCV3 was detected in 31 out of 106 and 12 out of 60 serum pools from vaccinated and non-vaccinated farms, respectively. Mean log 10 PCV3 genome equivalents were significantly (p < 0.05) lower in vaccinated farms (3.9 ± 0.8 log 10 copies/ml) than in non-vaccinated farms (4.4 ± 0.6 log 10 copies/ml). Concurrent PCV2 and PCV3 infection was rare and found only in 1 out of 529 and 4 out of 292 individual serum samples from vaccinated and non-vaccinated farms, respectively. Our results showed lack of impact of PCV3 circulation on PCV2 vaccine efficacy. On the other hand, intensive PCV2 circulation and high viremia detected in non-vaccinated farms did not seem to increase the level of PCV3 infection. K E Y W O R D SPCV2, PCV3, pigs, prevalence, qPCR, viremia

A molecular survey and phylogenetic analysis of porcine circovirus type 3 using oral fluid, faeces and serum

“…Subclusters have only been suggested by several authors who have compared PCV3's complete genomes; if our partial genome isolates are compared to their closest relatives, our sequences could be placed in either the PCV3a-IM subcluster or the PCV3b subcluster. It had been suggested that PCV2-PCV3 cross-protection might occur [21], though we did not expect it, nor was it found to occur.…”

“…On the other hand, this may suggest that infection is mostly subclinical or only clinically visible when co-factors enhance the primary effect of PCV3 [12]. The genomes of PCV2 and PCV3 are identical up to 37% and this raises questions concerning possible cross-immunogenicity [21]; in that case, anti-PCV2 vaccination should also eliminate or reduce PCV3 virus burden [15,22]. Since swine circovirus associated diseases are a problem faced by Slovenia's pig producers [23], we considered it likely that PCV3 was also present on Slovenian farms.…”

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

“…Samples with Ct values ≤37 were considered positive. The quantification of viral genome copies was performed using titrated plasmids containing ORF2 of PCV2 [33]. Viral titers inferred from the real-time PCR results are expressed as the log 10 viral copy number per milliliter of pool or oral fluid (copies/mL).…”

A Molecular Survey and Phylogenetic Analysis of Porcine Circovirus Type 3 Using Oral Fluid, Faeces and Serum

“…w/o suckling piglets, but this was not supported statistically [21]. We also vaccinated and tested a small group of animals in which PCV3 was discovered on Farm 5 and found that, while the number of PCV2-positive samples fell slightly, no noticeable change in PCV3 presence occurred.…”

“…The genomes of PCV2 and PCV3 are identical up to 37% and this raises questions concerning possible cross-immunogenicity [21]; in that case, anti-PCV2 vaccination should also eliminate or reduce PCV3 virus burden [15,22]. Since swine circovirus associated diseases are a problem faced by Slovenia's pig producers [23], we considered it likely that PCV3 was also present on Slovenian farms.…”