Molecular Typing of Ruminant Mycoplasmas: A Review

Abstract

Mycoplasmas are aetiologic agents for various diseases that cause tremendous socio-economic losses in the livestock industry such as Contagious bovine pleuropneumonia, Contagious caprine pleuropneumonia, Contagious agalactia, Mycoplasmal pneumonia of swine and chronic respiratory disease of chickens. Due to their fastidiousness, mycoplasmas are difficult to propagate invitro. Similarly, because of the multiplicity of the syndromes caused by these organisms their diagnosis is difficult. Traditionally, phenotypic methods such as biotyping, serotyping, phage typing, bacteriocin typing and antibiogram typing have been used to characterise and differentiate microbial strains involved in disease outbreaks. However, these methods have some disadvantages such as low discriminatory power and low reproducibility, lack of stability of some of the phenotypes and, they require maintenance of large stocks of reference strains. The deficiencies inherent in the phenotypic methods of microbial typing have led to the evolution of molecular and particularly nucleic acid-based typing methods which differentiate strains on the basis of their genetic material. Nucleic acid-based typing methods have a high discriminatory power, are highly reproducible and produce stable genotypes. Of the genotypic methods, pulsed-field gel electrophoresis and amplified fragment length polymorphism show a good potential for use in molecular typing and epidemiologic studies of bovine and caprine mycoplasma infections. This review focuses on methods for molecular typing of mycoplasmas with special emphasis on ruminant mycoplasmas