Comparative efficacy of PCR-based restriction fragment length polymorphism (RFLP) & multiplex PCR for glycoprotein B (gB) genotyping of human cytomegalovirus

Background & objectives: Glycoprotein B (gB), involved in cell-to-cell transmission of human cytomegalovirus (HCMV), is a critical factor in tissue tropism and viral pathogenesis. The aim of the present study was to compare the efficiency of PCR-based RFLP and multiplex nested PCR for gB gene of HCMV to determine their genotype in clinical specimens from patients with HCMV. Methods: The PCR based RFLP and the multiplex nested PCR were applied on standard strain of HCMV AD169, 4 clinical HCMV isolates and 70 clinical specimens positive for HCMV by pp65 antigenaemia assay or nested PCR for mtr II region or both. Results: Three of the four clinical isolates were genotyped as gBI and the other as gB3 by both the methods. HCMV genome in all the 70 clinical specimens were genotyped by multiplex nested PCR whereas only 65 were genotyped by PCR-based.RFLP. Forty one of 65 clinical specimens, gave concordant results by both methods. In the remaining 24, mixed infection with multiple genotypes was identified by multiplex nested PCR whereas single genotypes were identified by PCR-based RFLP. Interpretation & conclusion: Multiplex nested PCR provided a rapid, sensitive and cost-effective assay for gB genotyping of HCMV and allowed detection of multiple gB genotypes of HCMV in clinical samples compared to PCR-based RFLP.