It is known that deficiencies of micronutrients due to infections increase morbidity and mortality. This phenomenon depicts itself conspicuously in developing countries. Deficiencies of iron, vitamins A, E, C, B12, etc are widely prevalent among populations living in the third world countries. Helicobacter pylori (H pylori) infection has a high prevalence throughout the world. Deficiencies of several micronutrients due to H pylori infection may be concomitantly present and vary from subtle sub-clinical states to severe clinical disorders. These essential trace elements/micronutrients are involved in host defense mechanisms, maintaining epithelial cell integrity, glycoprotein synthesis, transport mechanisms, myocardial contractility, brain development, cholesterol and glucose metabolism. In this paper H pylori infection in associated with various micronutrients deficiencies is briefly reviewed.

Microdiversity (within individual genes) in the genomes of different Helicobacter pylori strains has been demonstrated to be more frequent than that seen in other prokaryotes. Point mutations in some genes, such as the vacA and 23S ribosomal RNA genes could result in the alteration of pathogenicity or antibiotic susceptibility of individual H. pylori strains. Development of a simple, rapid, and reliable screening method would be useful in the molecular characterization of genetic variation among different H. pylori strains.

The copP gene from H. pylori UA802 was used as a model for developing a mutation screening method. Four point mutations were introduced into the copP gene by in vitro site-directed mutagenesis and were verified by DNA sequencing. The mutated copP gene replaced the wild-type locus by natural transformation and homologous recombination. The site-specific mutants were screened by polymerase chain reaction (PCR) using 3'-end mismatched primers. The origins of the PCR fragments were demonstrated by Southern hybridization with the copP-derived DNA probe.

Three of these four mutations were characterized by PCR with the specific primers that contained the 3'-terminal nucleotide complementary only to the mutated nucleotide on both plasmid and chromosomal DNA templates. One mutation was able to be identified with the foregoing primer containing an additional wild-type nucleotide at its 3'-end. Point mutant screening with these specific primers offers 100% sensitivity in the aforementioned conditions. To achieve optimal screening, the concentration of magnesium and the annealing temperature have to be adjusted.

The procedure reported in this study is a simple, economical, rapid, and efficient approach in the identification of site-specific mutations on both plasmids and chromosomal DNA. Although the method was developed by using a specified H. pylori gene, it can be extended easily to other genes of interest in H. pylori or other organisms.