Computer-based analysis of Haemophilus parasuis protein fingerprints

Abstract

The present study aimed to compare the whole-cell protein profiles of Haemophilus parasuis field isolates by using a computer-based analysis, and evaluate the relationship between polyacrylamide gel electrophoresis (PAGE) type and virulence potential based on isolation site. A dendrogram clustering isolates with similar protein profiles was generated. Haemophilus parasuis isolates were grouped into 2 major PAGE type groups. The PAGE type II isolates were characterized by the presence of major proteins with molecular weights varying from between 36 and 38 kDa and included 90.7% of the isolates recovered from systemic sites, such as pleura, pericardium, peritoneum, lymph nodes, joints, and brain. Isolates classified as PAGE type I were characterized by the absence of this group of proteins and included 83.4% of the isolates recovered from the upper respiratory tract of healthy animals. The present study further corroborates the existence of a unique group of major proteins in potentially virulent H. parasuis isolates.

Figure 1

Cluster analysis of Haemophilus parasuis field isolates based on whole-cell protein profiles (sodium dodecyl sulfate polyacrylamide gel electrophoresis [SDS-PAGE], Pearson correlation, UPMGA). The scale indicates the percent of similarity. The columns in the figure indicate the isolate identification, site of isolation, serotype and genotype groups, as defined by Oliveira et al (10). Relevant clusters of strains are shown by gray lines. Clusters were defined based on the calculation of the point-bisectional correlation (BioNumerics).

Figure 2

Distribution of Haemophilus parasuis field isolates according to polyacrylamide gel electrophoresis (PAGE) type and site of isolation.