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

Abstract

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.

Detection and genotyping of Porcine circovirus 2 (PCV‐2) and detection of Porcine circovirus 3 (PCV‐3) in sera from fattening pigs of different European countries

“…In consequence, it is likely that the present study underestimates the real prevalence of both viruses in these countries, but provides further evidence of PCV-3 distribution in Europe, the frequency of (Wei, Xie, Theuns, & Nauwynck, 2019), while in the present study in the same country was slightly higher, showing a frequency of 29% (29/100) in farms without major clinical diseases. In France, the difference was even higher, with a 70% (47/67) of positivity herein and 14.3% and 40.2% of pigs at 10 and 16 weeks old, respectively in a study conducted in 2011 by Fablet et al (2011).…”

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

“…Furthermore, the 3'-terminal sequence of ORF2 of both recombinant strains contained three additional nt that resulted in an extra aa (K) on the tail part of the putative capsid protein (Supplementary Material S6). This is only seen in PCV2d and believed to facilitate the binding of the virus to the host cell (Wei, Xie, et al, 2019).…”

“…Since the PCV2 capsid is immunogenic (Karuppannan & Opriessnig, 2017;Segalés, 2012;Wei, Xie, et al, 2019) 65-87, 113-139, and 193-207) may help the virus to evade the immune response (Mahé et al, 2000;Wei et al, 2013 (Wei, Xie, et al, 2019). Kitts.…”

Strain-Dependent Porcine Circovirus Type 2 (PCV2) Entry and Replication in T-Lymphoblasts

“…Both strains 1121 and Stoon1010 belong to the PCV2a genotype. Since PCV2 shifts from PCV2a to PCV2b and later on to PCV2d [71,72], it would be interesting to examine the entry pathways of PCV2b and PCV2d strains, to see whether PCV2b and PCV2d strains during evolution use more efficient entry modes and whether the increased viral virulence results from a more efficient entry into host cells. This is the first study where we examined the entry features of strain 1121 which was isolated from an aborted fetus [34], since strain Stoon1010 which was isolated from a PMWS piglet was always used in all previous entry studies [25,29,33].…”