crip.umontreal.ca - Université de Montréal

Résumés/Abstracts
Delegates/Participants
Présentation orale no. 20
Proteomic analysis of outer membrane proteins of Actinobacillus pleuropneumoniae:
The emergence identification of porcine of immunogenic circovirus candidates 2b genotype for (PCV-2b) vaccine in development.
swine in Canada
Jacqueline W. Chung (1), Christopher Ng-Thow-Hing (1), Bernard F. Gibbs (2), John H.E. Nash (3), Mario
N. Music, , D. Tremblay, Jacques J. Harel, (4), and M.-H. James Venne, W. Coulton S. M. Elahi (1) et C. A. Gagnon
Groupe de recherche sur les maladies infectieuses du porc (GREMIP);
(1) Department of Microbiology and Immunology, McGill University, 3775 University Street, Montreal, QC, Canada H3A 2B4
(2) Sheldon Biotechnology Center, McGill University, 3773 University Street, Montreal QC, Canada H3A 3B4
(3) Institute for et Biological Service Sciences, de diagnostic; National Research Faculté Council de of Canada, médecine 100 Sussex vétérinaire Drive, Ottawa, (FMV),
ON, Canada K1A 0R6
(4) Groupe Université de recherche de sur Montréal les maladies (U infectieuses de Mtl), du porc, St-Hyacinthe, Département de Québec, pathologie et Canada.
microbiologie, Faculté de
médecine vétérinaire, Université de Montréal, St-Hyacinthe, QC, Canada J2S 7C6
Since late 2004, the swine industry in the province of Québec has
The Gram-negative bacterial pathogen Actinobacillus pleuropneumoniae (APP) causes porcine
experienced a significant increase in death rate related to postweaning
multisystemic wasting syndrome (PMWS). To explain this phenomenon, 2 hypotheses
were formulated: 1) the presence of a second pathogen could be exacerbating the
porcine circovirus 2 (PCV-2) infection, or 2) a new and more virulent PCV-2 strain
could be infecting swine. In 2005, 13 PMWS cases were submitted to the Québec
provincial diagnostic laboratory and PCV-2 was the only virus that could be found
constantly by PCR in all 13 samples. The PCR detection results obtained for other
viruses revealed the following: 61.5% were positive for porcine reproductive and
respiratory syndrome virus (PRRSV), 30.8% for swine influenza virus (SIV), 15.4% for
porcine parvovirus (PPV), 69.2% for swine torque teno virus (swTTV), 38.5% for swine
hepatitis E virus (swHEV) and 84.6% for Mycoplasma hyorhinis; transmissible
gastroenteritis virus and porcine respiratory coronavirus (TGEV/PRCV) was not
detected. Sequences of the entire genome revealed that these PCV-2 strains
belonged to a genotype (named PCV-2b) that has never been reported in Canada.
Further sequence analyses on 83 other Canadian PCV-2 positive cases submitted to
the provincial diagnostic laboratory during years 2005 and 2006 showed that 79.5%
of the viral sequences obtained clustered in the PCV-2b genotype. The
appearance of the PCV-2b genotype in Canada may explain the death rate
increase related to PMWS, but this relationship has to be confirmed.
pneumonia, a highly infectious respiratory disease that contributes to major economic losses in the swine industry.
With pressures to reduce the use of antibiotics in agricultural livestock, vaccination against bacterial pathogens has
emerged as a safer and more cost-effective approach for disease control. Current vaccines against APP provide
only partial protection, have little impact on morbidity, or are serotype-specific. Therefore an effective vaccine
offering cross-protection against different serotypes of APP is urgently needed. Outer membrane (OM) proteins,
localized at the bacterial cell surface, are attractive vaccine candidates because they are exposed as targets to
the immune system and play key roles in infection. Using the genome sequence of APP serotype 5b, we scanned in
silico for proteins predicted to be localized at the cell surface and constructed a consensus prediction list of 93 OM
proteins. We previously described proteomic analyses utilizing 1D gel electrophoresis, followed by identification with
LC-MS/MS. The outcome established the first OM proteome of APP grown under nutrient-rich conditions. We
identified 47 OM proteins representing 50% of the predicted OM proteome, most of which have not been
characterized. We now describe differences in OM protein profiles between APP grown under nutrient rich
conditions and under nutrient deprived conditions that resemble those in vivo: iron-restriction; growth-factor
nicotinamide adenine dinucleotide-restriction. Furthermore, we detected immunoreactive OM proteins by
immunoblot analyses of 1D and 2D gels probed with post-convalescent sera from infected animals. These studies
direct our selection of potential vaccine candidates for APP that are immunogenic and are expressed under
conditions that reflect infection in the porcine host.
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