Biological characterization of Pasteurella multocida present in the Saiga population

Abstract

BackgroundThis study provides biochemical and molecular genetic characteristics of P. multocida isolated from dead saigas in 1988, 2010–2015 on the territory of the Republic of Kazakhstan.ResultsBacteriological samples taken from carcasses of saiga antelope during mortality events recorded in West Kazakhstan in both 2010 and 2011 and in Kostanay in 2012 and 2015 confirmed the presence of P. multocida, according to morphological and biochemical characterisation. Only in the event of 2015 was the agent proven to be the causative agent of the disease observed, haemorrhagic septicaemia. In the other mortality events it is not certain if the organism was a primary aetiology or an incidental finding as confirmatory pathological investigation was not undertaken. The implemented phylogenetic analysis of ribosomal RNA 16S gene allowed us to identify Pasteurella strains isolated in 2010–2015 as P. multocida subspecies multocida. Capsular typing by PCR showed that the studied strains isolated from dead saiga in 2010, 2011, 2012 and 2015 belonged to serotype B. MLST analysis showed that these strains of P. multocida are of the capsule type B and form one clonal grouping with isolates ST64, ST44, ST45, ST46, ST44, ST47 which isolated from cases of hemorrhagic septicemia of animals in Hungary, Burma, Sri Lanka, Pakistan and Spain. Sixteen virulence genes of the five strains of P. multocida, isolated from saigas were studied using multiplex PCR. ptfA, ompA, ompH, oma87, plpB, fimA, hsf-2, pfhA, exbB, tonB, hgbA, fur, nanB, nanH and pmHAS genes were detected in all strains. The toxA gene was not identified in the studied strains. The phylogenies of these isolates is compared across saiga populations and years and the 2015 isolate was compared to that of an isolate from a disease outbreak in 1988 and the findings suggest that these isolated bacteria are stable commensals, opportunistically pathogenic, being phylogenetically uniform with very little genetic variation notable over the last 4 decades.ConclusionIsolation, phenotypic and genetic characterization of the P. multocida isolates inform understanding of the epidemiology of infection in saigas and predict virulent potential of these opportunistic bacteria.

Mass Die-Off of Saiga Antelopes, Kazakhstan, 2015

“…Microbiologic and virologic diagnostic methods showed that in samples from >90% of saiga antelopes that died in 2015, the cause was pasteurellosis ( 3 , 6 ). Previous studies had demonstrated the absence of other potential causative agents by diagnostic PCR, including bacteria (e.g., anthrax bacillus, Coxiella burnetti , Erysipelothrix rhusiopathiae , and Listeria spp.…”

“…Previous studies had demonstrated the absence of other potential causative agents by diagnostic PCR, including bacteria (e.g., anthrax bacillus, Coxiella burnetti , Erysipelothrix rhusiopathiae , and Listeria spp. ), mycoplasma (e.g., Mycoplasma ovipneumoniae ), and virus diseases (e.g., foot-and-mouth disease, bluetongue, PPR, epizootic hemorrhagic disease, sheep pox, Akabane, Aujesky’s disease, bovine viral diarrhea, visna-maedi, and malignant catarrhal fever) ( 3 , 6 ). Furthermore, these studies used capsular typing with specific primers to show that strains of P. multocida from saiga antelopes belonged to serogroup B ( 3 , 6 ).…”

“…), mycoplasma (e.g., Mycoplasma ovipneumoniae ), and virus diseases (e.g., foot-and-mouth disease, bluetongue, PPR, epizootic hemorrhagic disease, sheep pox, Akabane, Aujesky’s disease, bovine viral diarrhea, visna-maedi, and malignant catarrhal fever) ( 3 , 6 ). Furthermore, these studies used capsular typing with specific primers to show that strains of P. multocida from saiga antelopes belonged to serogroup B ( 3 , 6 ). Our 16S analysis also showed that the P. multocida isolated from saiga antelopes in 2015 in Akmola and Kostanay oblasts were genetically identical to the bacteria isolated from saiga antelopes in 1988, 2010, 2011, and 2012, as well as P. multocida subsp .multocida _PM30 strain (GenBank accession no.…”

“…Our 16S analysis also showed that the P. multocida isolated from saiga antelopes in 2015 in Akmola and Kostanay oblasts were genetically identical to the bacteria isolated from saiga antelopes in 1988, 2010, 2011, and 2012, as well as P. multocida subsp .multocida _PM30 strain (GenBank accession no. AY299312) isolated from ill cattle with hemorrhagic septicemia in 2004 ( 6 ). …”

“…Laboratory results on the microbiologic, pathologic, and environmental conditions at the time of the 2015 outbreak suggested hemorrhagic septicemia caused by Pasteurella multocida serotype B and triggered by environmental conditions ( 3 , 6 ). However, whether a second unknown infectious agent had predisposed the animals to infection with P. multocida was unclear from the laboratory results.…”