A capsule/lipopolysaccharide/MLST genotype D/L6/ST11 of Pasteurella multocida is likely to be strongly associated with swine respiratory disease in China

Abstract

Pasteurella multocida is a leading cause of respiratory disease in pigs worldwide. In this study, we determined the genetic characteristics of 115 P. multocida isolates from the lungs of pigs with respiratory disease in China in 2015 using capsular typing, lipopolysaccharide (LPS) genotyping, and virulence genotyping based on the detection of virulence-associated genes. The results showed that the isolates belonged to three capsular types: A (49.6%), D (46.1%), and nontypable (4.3%); and two LPS genotypes: L3 (22.6%) and L6 (77.4%). When combining the capsular types with the LPS genotypes, a genotype group D: L6 (46.1%) was the most prevalent among the strains. Among the 23 virulence-associated genes detected in this study, a small number of them displayed a certain level of "genotype-preference". We found that pfhA, hgbA, and hgbB had a close association with P. multocida LPS genotypes, while tadD was more associated with P. multocida capsular types. In addition, multilocus sequence typing (MLST) on 40 P. multocida isolates identified four sequence types: ST3, ST10, ST11, and ST16, and the distribution of ST11 was significantly higher than the other MLST genotypes. Interestingly, all of the ST11 isolates detected in this study were genotype D: L6 strains and they were 100% positive for hgbB. Our data suggest that a capsule/LPS/MLST genotype D/L6/ST11 is likely to be strongly associated with respiratory clinical manifestation of the disease in pigs.

Genetic and Phylogenetic Characteristics of Pasteurella multocida Isolates From Different Host Species

“…The predominate capsule: LPS genotypes defined among the porcine isolates were types D: L6 (42.86%), A: L3 (25.00%), and A: L6 (23.21%). Those are because P. multocida strains with porcine pasteurellosis are frequently designated capsular types A and D (Tang et al, 2009 ; Liu et al, 2017 ; Peng et al, 2018 ), and LPS serovars 3, 4, and 12 (Pijoan et al, 1983 ; Lainson et al, 2002 ; Jamaludin et al, 2005 ). In particular, these results are in agreement with the latest molecular epidemical data in China (Peng et al, 2018 ).…”

“…A total of 47 P. multocida strains were selected for whole genome sequencing in this study (Table 1 ). Most of these strains were isolated from pigs with respiratory disorders in China (Peng et al, 2018 ), with the exception of strain HN04, which is a capsular type B isolate from a swine haemorrhagic septicaemia case. The capsular types and LPS genotypes of these 47 P. multocida isolates were determined through PCR assays, as described previously (Townsend et al, 2001 ; Harper et al, 2015 ).…”

“…The capsular genotypes and LPS genotypes of the 47 P. multocida strains sequenced were determined using PCR methods (Townsend et al, 2001 ; Harper et al, 2015 ) and are documented on our previous publication (Peng et al, 2018 ). Capsular genotypes and LPS genotypes of the 62 P. multocida genomes from NCBI genome database were determined by blasting the oligonucleotide sequences designed for capsular typing (Townsend et al, 2001 ) and LPS genotyping (Harper et al, 2015 ) against their WGSs, respectively.…”

“…Therefore, molecular typing methods have been developed to help assign P. multocida into five capsular genotypes (A, B, D, E, F) (Townsend et al, 2001 ) and eight LPS genotypes (L1-L8) (Harper et al, 2015 ). In addition, the multilocus sequence typing method has been also designed for P. multocida (Subaaharan et al, 2010 ), and it has been widely used in epidemiology and surveillance (Hotchkiss et al, 2011 ; Moustafa et al, 2013 ; Fernández-Rojas et al, 2014 ; Peng et al, 2018 ).…”

Investigation of genetic diversity and epidemiological characteristics of <i>Pasteurella multocida</i> isolates from poultry in southwest China by population structure, multi-locus sequence typing and virulence-associated gene profile analysis

“…The new ST342 strain from CC129 clonal complex also exhibits similar virulence (LD50=65) compared to the ST129 strain, so possible hazards from the ST342 strain in poultry cannot be underestimated. Interestingly, during virulence genotyping, we also found that the some genes displayed a certain level of “genotype-preference” [ 27 ]. For instance, isolates belonging to ST129 were with the genes ompH+plpB+ptfA+tonB , whereas ST342 included isolates with fur+hgbA+tonB genes.…”