Infection of Cesarean-Derived Colostrum-Deprived Pigs with Porcine Circovirus Type 2 and Swine Influenza Virus

Department of Comparative Pathobiology, Purdue University, West Lafayette, Indiana, USA.
Comparative medicine (Impact Factor: 0.74). 02/2010; 60(1):45-50.
Source: PubMed


Porcine circovirus type 2 (PCV2) and swine influenza virus (SIV) are important pathogens for porcine respiratory disease complex, which is economically significant worldwide. The pathogenesis of PCV2-SIV coinfection is unknown. In this study, we focused on establishing a challenge model for PCV2 to determine whether SIV influences PCV2 replication and increases the severity of PCV2-associated disease. Cesarean-derived colostrum-deprived pigs were inoculated intratracheally with cell culture medium only (negative control group), PCV2 only, or PCV2 followed 1 wk later with SIV H1N1. Two pigs from each group were necropsied at 12, 21, 28, and 35 d after inoculation. Coinfection with SIV did not increase the number of PCV2 genomic copies in serum or target tissues or the severity of microscopic lesions associated with PCV2 in lung or lymph node. The antibody titer to PCV2 did not differ significantly between PCV2-SIV- and PCV2-infected groups. In conclusion, SIV H1N1 did not influence PCV2 replication in dually infected pigs in this study.

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    • "In addition, experimental coinfections with PCV2 and PPV resulted in PMWS reproduction in gnotobiotic, colostrum-deprived pigs (Ellis et al. 1999). Other pathogens which have been reported to be capable of participating in the establishment of PMWS include Mycoplasma hyopneumoniae (Pallares et al. 2002), Cryptosporidium parvum (Nunez et al. 2003), Aujeszky's disease virus (Quintana et al. 2001; Maldonado et al. 2005), influenza virus and bacterial pneumonias (Kim et al. 2002; Pogranichniy et al. 2002; Dorr et al. 2007; Wei et al. 2010). Against such a background, a search for a role for PCMV in PMWS, particular in view of the immunosuppressive potential of PCV2, would be expected to reveal some sort of interaction. "
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    ABSTRACT: Porcine cytomegalovirus (PCMV) is a Betaherpesvirus that causes lifelong latent infections in swine; occasionally, it may be associated with inclusion body rhinitis in piglets and reproductive disorders in pregnant sows. Post-weaning multisystemic wasting syndrome (PMWS) a condition where porcine circovirus type 2 (PCV2) infection is necessary – though not sufficient – to trigger disease, has become one of the major health problems to the porcine productive chain. Despite the high expected prevalence of both PCMV and PCV2 in swine-raising farms, no links between PCMV and PMWS have been investigated so far. In view of that, the present study was conducted to search for relations between PCMV infections and the occurrence of PMWS. Spleen and sera of PMWS-affected and non-PWMS-affected animals were examined. In PMWS-affected animals, PCMV DNA was detected in 88.4% of the spleen samples and 7.6% of the sera, whereas in non-PMWS-affected pigs, PCMV DNA was detected in 72.7% of the spleens and 10% of sera. Such differences were not statistically significant. These findings showed despite the high prevalence of PCMV infections in the swine population examined, no positive or negative association could be inferred from the presence of PCMV DNA and the occurrence of PMWS.
    Full-text · Article · Jul 2015
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    • "Several studies based on experimental dual infections of pigs have been conducted to understand interactions between SIVs and PRRSV, PCV-2, Mhp, PRCV or Bordetella bronchiseptica, pathogens that are frequently detected in herds (Lanza et al., 1992; Loving et al., 2010; Thacker et al., 2001; Van Reeth et al., 1996, 2001; Van Reeth and Pensaert, 1994; Wei et al., 2010; Yazawa et al., 2004). Among them, Mhp is one of the pathogens that is most commonly isolated from pigs with clinical signs of PRDC. "
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    ABSTRACT: Swine influenza virus (SIV) and Mycoplasma hyopneumoniae (Mhp) are widespread in farms and are major pathogens involved in the porcine respiratory disease complex (PRDC). The aim of this experiment was to compare the pathogenicity of European avian-like swine H1N1 and European human-like reassortant swine H1N2 viruses in naïve pigs and in pigs previously infected with Mhp. Six groups of SPF pigs were inoculated intra-tracheally with either Mhp, or H1N1, or H1N2 or Mhp+H1N1 or Mhp+H1N2, both pathogens being inoculated at 21 days intervals in these two last groups. A mock-infected group was included. Although both SIV strains induced clinical signs when singly inoculated, results indicated that the H1N2 SIV was more pathogenic than the H1N1 virus, with an earlier shedding and a greater spread in lungs. Initial infection with Mhp before SIV inoculation increased flu clinical signs and pathogenesis (hyperthermia, loss of appetite, pneumonia lesions) due to the H1N1 virus but did not modify significantly outcomes of H1N2 infection. Thus, Mhp and SIV H1N1 appeared to act synergistically, whereas Mhp and SIV H1N2 would compete, as H1N2 infection led to the elimination of Mhp in lung diaphragmatic lobes. In conclusion, SIV would be a risk factor for the severity of respiratory disorders when associated with Mhp, depending on the viral subtype involved. This experimental model of coinfection with Mhp and avian-like swine H1N1 is a relevant tool for studying the pathogenesis of SIV-associated PRDC and testing intervention strategies for the control of the disease.
    Full-text · Article · Dec 2011 · Veterinary Microbiology
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    • "SIV and PCV2 are often implicated in field cases of PRDC. A recent study undertaken by a group of researchers who wanted to verify a potential synergistic relationship between PCV2 and SIV, concluded that even though the PCV2-SIV co-infected group developed severe disease, no significant differences were found between the coinfected and singularly infected groups (Wei et al., 2010). v. Porcine torque teno virus (TTV). "
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    ABSTRACT: Porcine circovirus associated disease (PCVAD) has made an economic impact in global swine production, is caused by porcine circovirus type 2 (PCV2) and manifests in forms of multisystemic disease, wasting, pneumonia, diarrhea in growing pigs and reproductive failure in gilts and sows. PCVAD is enhanced by PRRSV co-infection alongside PCV2 infection in pigs and is not very well understood except that PRRSV potentiates PCV2 replication in the host. We characterized apoptosis in gnotobiotic pigs caused by both PCV2a and PCV2b and for the first time established that both PCV2a and PCV2b are able to promote cell death in the hepatocytes of gnotobiotes of clinically affected pigs leading to hepatic failure. We further delineated the role of PRRSV in affecting PCV2a and PCV2b apoptosis in specific pathogen free (SPF) pigs and demonstrated that PRRSV does not cause apoptosis induction in PCV2a and PCV2b infected pigs. We compared and demonstrated that in vitro differences in PCV2 or PRRSV replication or IFN gamma; and IL-10 release in porcine alveolar macrophages (PAMs) inoculated with several PCV2-PRRSV combinations are small and not dependent on ORF1 or ORF2 origin. We analyzed the shedding of both PCV2a and PCV2b in piglets co-infected with PRRSV and ascertained that PRRSV is capable of prolonging PCV2 viremia and subsequent shedding in the nasal, oral secretions and fecal excretion that can increase horizontal transmission of PCV2a and PCV2b in nayve herds. Finally we also verified if prior PRRSV exposure had any detrimental effect on PCV2 vaccines currently available in the US market. We were able to establish that the PCV2 vaccines are able to provide protective immunity to piglets that had prior PRRSV infection.
    Full-text · Article · Jan 2011
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