Molecular Analysis of Oapa Gene in Haemophilus influenzae Strains Isolated from Iran: As a Domestic Vaccine Candidate

Haemophilus influenzae is a bacterium that can act as a pathogen of human respiratory tract. Its infections have been traditionally treated with antibiotics, and then the use of conjugate vaccines has been very successful in prevention of infectious diseases. These vaccines consisted of capsular polysaccharide of H. influenzae with an immunogenic protein. The aim of this study was molecular analysis of oapA gene in Iranian H. influenzae strains as a conserve immunogenic protein for vaccine candidate. Clinical H. influenzae strains were collected from Milad Hospital in Tehran, and cultured on chocolate agar. After diagnostic test, biochemical tests were performed for distinguishing strains biotype. The DNA extracted by boiling method and specific PCR reactions were designed for oapA gene molecular analysis. Finally sequencing of PCR products was performed for confirming our results. The results of PCR exhibited that 79% of clinical samples had 95-99% similarity to NCBI sequences of H. influenzae oapA gene, and the remaining 21% had a 125 nucleotide deletion and 94-96% similarity to NCBI sequences. Also this study showed that all strains having 125 nucleotide deletion (Nontypeable H. influenzae and H. influenzae type b) had 95-99% similarity to NCBI sequences. The results of determining the biotype revealed that the studied strains were related to different biotypes. The results of this study suggested that use of oapA gene protein for production of vaccine against H. influenzae type b be further considered.