To assess the extent of interstrain variation, 50 isolates of Mycoplasma (M.) bovis including the type strain PG45 were examined for the presence of a family of variable membrane surface lipoproteins (Vsps) and their genes. Southern hybridization using a genomic fragment carrying three distinct vsp genes (vspAEF) revealed a striking heterogeneity, with only 2/50 strains having identical banding patterns. Cluster analysis of the data showed that most isolates from interrelated herds (groups 1, 2 and 3) were combined in a cluster of 50% homology, while isolates from distinct geographical regions (groups 4, 5 and 6) were linked only at 18% homology. Vsp antigen expression was monitored by Western immunoblotting using four specific monoclonal antibodies (MAbs). Resembling the findings at the DNA level, interstrain variation of Vsp expression among groups 1-3 was less pronounced than among non-interrelated isolates from groups 4-6. Ten out of 50 strains did not hybridize with the vspAEF gene probe at high-stringency conditions, 8/50 failed to react with any of the Vsp-related MAbs, and 6/50 proved negative in both assays. Interestingly, most of these isolates produced hybridization signals at low stringency suggesting major distinctions in their vsp gene structure. The extensive evidence obtained on interstrain vsp gene polymorphism and variation in Vsp expression could provide a basis for a future understanding of the pathogenic potential of individual M. bovis strains. Copyright (C) 1998 Elsevier Science B.V.
Bibliographical noteFunding Information:
This study was supported by the German–Israeli Foundation for Scientific Research and Development (GIF), grant I-367–147.13/94. The authors thank Sharon Levisohn, Itziar Pérez, Robin Nicholas, Francois Poumarat, and Kriton Sarris for providing field isolates. We are also grateful to Christine Citti, Veterinary University of Vienna, for providing the clonal expression variants.
- Antigenic variation
- Field isolates
- Mycoplasma bovis
- Restriction fragment length polymorphism (RFLP)
- Surface proteins