A new emerging genotype subgroup within PCV-2b dominates the PMWS epizooty in Switzerland

Wiederkehr, D.; Sydler, Titus; Buergi, E.; Haessig, Michael; Zimmermann, Dieter R.; Pospischil, Andreas; Brugnera, Enrico; Sidler, Xaver

doi:10.1016/j.vetmic.2008.10.028

Cited by 84 publications

(75 citation statements)

References 27 publications

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“…The PCV2c genotype has only been found in Denmark to date [31]. In recent years, several reports have suggested that PCV2b is the predominant genotype in many countries worldwide, including Brazil [8,11], Canada [14,15], China [17,21,38], Cuba [29], Denmark [12], Germany [30], Japan [32], Korea [1,2,19,20], Slovakia [37], Spain [10], Sweden [33], Switzerland [39], Thailand [18] and the U.S.A. [6,23]. PCV2b might be more pathogenic than PCV2a [16,32].…”

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Genotypic Change and Phylogenetic Analysis of Porcine Circovirus Type 2 in Taiwanese Pig Herds

et al. 2012

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ABSTRACT. Porcine circovirus type 2 (PCV2) is the primary causative agent of postweaning multisystemic wasting syndrome. Two major PCV2 genotypes, PCV2a and PCV2b, have been identified. To explore the prevalence of different subgroups of PCV2 in Taiwan Porcine circovirus type 2 (PCV2) is the primary causative agent of porcine circovirus-associated diseases (PCVADs) in pigs and causes significant economic losses in most pig-producing countries [27]. PCVADs can be subclinical or can include 1 or more clinical manifestations such as multisystemic disease with weight loss, respiratory signs, enteric signs, porcine dermatitis and nephropathy syndrome, and reproductive problems individually or in combination in pigs raised on farms or in other groups of pigs [27]. PCVADs are multifactorial syndromes, and factors that are currently thought to influence the outcome of PCV2 infection include the viral strain, the host, coinfections, and immune modulation [27].PCV2 is a small, non-enveloped, circular, single-stranded DNA virus containing a circular genome of 1766-1768 nucleotides [17,34]. PCV2 is a member of the genus Circovirus of the family Circoviridae [27]. Another member of this genus includes PCV1, which does not produce disease in pigs [35]. The PCV2 genome contains three open reading frames (ORFs). ORF1 encodes two replicase proteins, Rep and Rep' [4]. The viral capsid protein is encoded by ORF2 [25], which is involved in the host immune response [24]. The third ORF, ORF3, is in a different reading frame embedded within ORF1 and encodes a protein associated with apoptosis [22].PCV2 viruses are further classified into three genotypes (2a, 2b, and 2c) that differ with respect to the ORF2 sequence [9,26]. The signature motif (amino acid positions 86-89) of ORF2 can be used to distinguish PCV2a and 2b, which contain the TNKI and SNPR (L) motifs, respectively [6]. The PCV2c genotype has only been found in Denmark to date [31]. In recent years, several reports have suggested that PCV2b is the predominant genotype in many countries worldwide, including Brazil [8,11], Canada [14,15] [16,32]. In Taiwan, the first PCV2 outbreak was confirmed in 2001 [3], and a high prevalence of PCV2 infection was noted thereafter. Up to 92% of pig herds and 68.8% of weaned pigs were infected by PCV2 in Taiwan [7]; however, the genotype prevalence of PCV2 in Taiwan is not currently known. The aim of the present study was to investigate the prevalence of the PCV2 genotype in Taiwan in the last decade. MATERIALS AND METHODS Specimen collection and histopathological examination:Clinical samples (lungs, lymph nodes, spleen, brain and serum) were collected from 785 pigs from 186 herds in central and southern Taiwan during 2002-2011. These samples were mainly acquired from weaning and growing pigs with

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Genotypic Change and Phylogenetic Analysis of Porcine Circovirus Type 2 in Taiwanese Pig Herds

et al. 2012

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“…Nevertheless, elevated antibody titers that are due to vaccinations of piglets against PCV2 do not last until finisher stage [13]. Although PCVDs were only described in Switzerland in 2001 [14], PCV2 has been present in the Swiss pig population since at least 1979 [15]. In a prevalence study from 2001-2002, only four out of seventytwo (5%) wasting piglets from 26 different farms were diagnosed with PCV2-systemic disease (PCV2-SD) [16].…”

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“…Despite this high sero-prevalence, few cases of PCVDs were reported in Switzerland before 2003 [15]. The sudden onset of an epizootic correlated with a genetic shift from PCV2a group members to a specific PCV2b group member that we named PCV2b-CH [15].Importantly, Switzerland is free of porcine reproductive and respiratory syndrome virus (PRRSV), enzootic pneumonia and actinobacillosis, which play roles in disease development in PCVDs [17].With the introduction of piglet vaccination in Switzerland in 2008, the number of PCV2-SD cases decreased dramatically.There were two aims of this study. First, we sought to gain a general understanding of how humoral responses appear in a persistently infected population under three different conditions.…”

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Antibody Titers from Finisher Populations with Persistent/Latent PCV2 Infection Before, During and After the PCV2-SD Epizootic

Vybiral¹,

Sydler²,

Haessig³

et al. 2017

Epidemiology

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Porcine circovirus type 2 (PCV2) diseases (PCVDs) have affected pig production worldwide over the last three decades. Since the advent of mass vaccination, manifestations of PCVDs have dramatically decreased. Nevertheless, persistent/latent PCV2 infections linger in the pig population.Therefore, we investigated whether conclusions can be drawn regarding the health status of a population based on humoral responses to a persistent pathogen such as PCV2. We examined the Swiss finisher population because in this population, time points associated with major events have been well documented. We measured PCV2-specific antibody titers of finishers before the Swiss epizootic in 1996-97 and compared these titers with antibody titers in 2006, during the peak of the epizootic, and in 2011, three years after the start of the mass vaccination of piglets.Two hundred serum samples from finishers were analyzed for each of these time periods, which correspond to before, during and after the Swiss epizootic. PCV2-specific IgG antibody titers were low to modestly positive during the pre-epizootic and post-epizootic periods. At the peak of the epizootic in 2006, almost all serum samples were positive, with higher average IgG concentrations than those detected in pre-epizootic and post-epizootic samples. Moreover, IgM antibodies were analyzed for 60 randomly chosen finishers in each time period. Of these 180 samples, only two serum samples from 2006 contained PCV2-specific IgM antibodies.Mass vaccination against PCV2 reduced PCV2-specific antibody titers in pigs with persistent/latent infection to pre-epizootic levels. Our data show prevalence for and concentrations of IgG-specific PCV2 antibodies, which appear to be correlated with PCVD. This result is counterintuitive because one would typically expect higher antibody concentrations to be associated with less disease; a possible interpretation is that elevated concentrations of immature anti-PCV2 antibodies provided pigs with a certain level of protection against PCVDs.Keywords: PCV2-specific IgG and IgM; Population study; Seroprevalence; Persistent/latent infections; Epizootic periods; Mass vaccination campaign Short CommunicationPorcine circovirus type 2 (PCV2), which is one of the most significant pathogens in pig production worldwide, is the causative agent of porcine circovirus diseases (PCVDs). PCV2 can be detected in both healthy and diseased pigs [1] and is found in the lymphatic system in most pigs [2,3].We and others have demonstrated that PCV2 affects the maturation and differentiation of T cells [3][4][5]. We specifically identified T helper cells as being targeted by PCV2-infected cells in the thymus [4]. These T helper cells are essential for the proper maturation of high-affinity antibody-secreting centroblasts [6]. Overall, humoral responses to PCV2 do not correlate with the infection statuses of pigs [4,7,8].This result is unsurprising due to the latent nature of PCV2, which is found in pig fetuses before immune competency [3,4]. In addition, current infor...

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“…According to the aid of a signature motif, which was a short amino acid motif encoded within the capsid protein, PCV2 was separated into at least 2 major groups, PCV2a and PCV2b. This classification received more attention, as it seemed to define PCV2b to be more virulent (6). However, little is known about the role of PCV2b in semen from PCV2b-infected male mice and the transmission of PCV2b from semen to fetuses via artificial insemination.…”

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Vertical transmission of porcine circovirus 2b (PCV2b) to mouse fetuses in maternal uterus by artificial insemination with semen from PCV2b-infected male mouse

Zhi-bang¹,

Qianlong²,

Wang³

et al. 2013

Turk J Vet Anim Sci

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A new emerging genotype subgroup within PCV-2b dominates the PMWS epizooty in Switzerland

Cited by 84 publications

References 27 publications

Genotypic Change and Phylogenetic Analysis of Porcine Circovirus Type 2 in Taiwanese Pig Herds

Genotypic Change and Phylogenetic Analysis of Porcine Circovirus Type 2 in Taiwanese Pig Herds

Antibody Titers from Finisher Populations with Persistent/Latent PCV2 Infection Before, During and After the PCV2-SD Epizootic

Vertical transmission of porcine circovirus 2b (PCV2b) to mouse fetuses in maternal uterus by artificial insemination with semen from PCV2b-infected male mouse

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