MOLECULAR BIOLOGY, MOLECULAR PHYLOGENY, AND MOLECULAR DIAGNOSTIC APPROACHES TO THE MICROSPORIDIA

The recognition of microsporidia as opportunistic pathogens in humans has led to increased interest in their molecular biology. Much of the recent work has focused on determination of the nucleotide sequences for rRNA genes. These sequences have been used in the development of diagnostic tools for species identification. In addition, such rRNA gene sequences have facilitated the development of a molecular phylogeny of these organisms. Given the increasing evidence of the importance of the microsporidia as both human and agricultural pathogens, recent work has focused on the identification of microsporidial genes that could serve as potential therapeutic targets. Prior to the advent of comparative analysis of molecular data, the classification of eukaryotes was based on morphological, ecological, and physiological characteristics. Speculation based on this information is problematic because the homology among such characters is often not discernible and characters that could be considered were thought to be either shared or derived depending on the underlying hypothesis used in construction of the phylogeny. A much different view of the phylogenetic placement of the Microspora has been suggested based on analysis of β-tubulin genes. The molecular data present an excellent means of identifying a species and provide an excellent data set for proposing evolutionary relatedness through phylogenetic analysis. Molecular techniques for the diagnosis of microsporidiosis appear to have high sensitivity and specificity. These methods have proven extremely useful both in the identification of animal models as well as in investigations of the epidemiology of microsporidia pathogenic to humans.