Molecular analysis of the human cytomegalovirus strains isolated from infected infants.

Polymerase chain reaction (PCR) techniques were developed to facilitate the study of the molecular epidemiology of human cytomegalovirus (HCMV). In the present study analysis of HCMV DNA was applied for the determination of the reinfection frequency and genotypes of HCMV strains isolated from infected infants, treated with ganciclovir and non-treated. Urines from 92 infants, aged 1 to 5 months, were investigated. Isolates were analysed by PCR method using primers for a-seq and glycoprotein B (gB) HCMV genes. PCR products of gB gene were digested with RsaI and HinfI endonucleases (PCR-RFLP). A-seq gene amplified products were visualized on agarose gels and analysed by densitometry. Genotyping based on hypervariable a-seq region in comparison with restriction analysis of gB gene fragment allowed better differentiation and discrimination of particular HCMV strains. Analysis of the a-sequence PCR products allowed to distinguish 9 profile groups. The patterns obtained consisted of fragments with different size (100 bp to 350 bp), suggesting considerable diversity of HCMV strains. A-sequence analysis revealed that 5 (15.6%) of treated children and 14 (20.7%) of those non-treated, excreted virus of stable genotype. Twenty one (65.6%) of treated and 32 (52.5%) of non-treated children excreted HCMV with a-sequence product of different size, suggesting that in these cases reinfection was caused by genetically distinct strains. Results suggest that reinfection is more frequent in children treated with ganciclovir.