Variability of a glucose phosphotransferase system permease in Mycoplasma mycoides subsp. mycoides Small Colony

Abstract

Intraclonal antigenic variation in pathogenic mycoplasma species is considered an important feature of host-pathogen interaction. Such intraclonal protein variation was observed for the interaction of Mycoplasma mycoides subsp. mycoides Small Colony, the agent of contagious bovine pleuropneumonia, with mAb 3F3. Colony immunostaining allows the definition of 3F3 ON-and 3F3 OFF-type variants, which revert at low frequency. Targets of mAb 3F3 were shown to be surface located, and resided on multiple polypeptides in the 58-68 kDa size range. Phage display and a genomic database were combined to determine the gene encoding the proteins recognized by mAb 3F3. A gene encoding the putative permease of the glucose phosphotransferase system was identified. Genome sequence analysis of strain PG1 revealed two highly similar copies of this gene, resulting from duplication of the chromosomal region carrying the gene. Southern blot analysis demonstrated the presence of this duplication in almost every African strain tested, but not in European strains. DNA analysis revealed that ON/OFF switching is governed by a base substitution occurring upstream of the coding region for the 3F3 epitope. This event generates a stop codon that results in the premature termination of the PtsG protein. INTRODUCTIONMycoplasma mycoides subsp. mycoides biotype Small Colony (Mmymy SC) belongs to the class Mollicutes, trivial name mycoplasma, whose members are distinguished from other bacteria by their minute size and total lack of a rigid cell wall. Mmymy SC is the aetiological agent of contagious bovine pleuropneumonia (CBPP), a highly contagious respiratory disease in cattle. CBPP is the only bacterial disease included in the A list of the World Organization for Animal Health (OIE), which contains prioritized communicable animal diseases. During the nineteenth century, CBPP spread throughout the world, causing extensive losses in livestock. By prohibiting cattle movement, and by a programme of slaughtering and vaccination, CBPP was eradicated during the twentieth century, except in Africa and limited areas of Europe and Asia. Since the late 1980s, CBPP has become the major infectious disease affecting livestock in Africa, and the number of countries with CBPP-infected animals rose dramatically from 15 in the late 1970s to 26 in 2002 [Nicholas et al., 2000; OIE official data (www.oie.int)]. CBPP was thought to be almost eradicated from Europe by the early twentieth century, and until the 1960s only a few sporadic outbreaks continued to occur in the Iberian Peninsula. However, from 1980 onwards, hundreds of outbreaks were reported in France, Portugal, Spain and Italy. Control programmes were set up and no case of CBPP has been officially documented in Europe since 1999 (Portugal).Abbreviations: CBPP, contagious bovine pleuropneumonia; glucose PTS, phosphoenolpyruvate : glucose phosphotransferase system; HSA, human serum albumin; Mmymy SC, Mycoplasma mycoides subsp. mycoides biotype Small Colony. 0002-7247 G 2004 SGM Printed in Great Britain 4009Mic...

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