Identification of adenovirus 7h heterogeneity in the E3 region

Adenovirus genotype 7h was previously reported to be originated from a recombination event between adenovirus genotypes 7p and 3p. Based on those findings, further characterization of other adenovirus 7h strains become important to determine whether all adenovirus 7h strains arose from a single recombinational event. To explore such a possibility, 160 clinical isolates were studied after developing a PCR assay using a primer set designed to amplify the region corresponding to E3-7,7 Kd of adenovirus ADV 7p and E3-9 Kd of adenovirus 3p. The assay was able to differentiate most of the subgenus B strains from adeno 7h with the genotype 3d. The study of several adenovirus 7h clinical isolates revealed the existence of three variants of adeno 7h. One of the variants, 7h3, shows a high degree of similarity with gene E3-9 Kd of ADV 3p, but lacks the corresponding AUG codon. Our results suggest that more than one recombination event may explain the detection of three different types of adenovirus 7h. The genotype variants of adeno 7h were detected in different years, indicating that the recombination events took place independently from each other. The study of the recombination region may allow further understanding of the function of several viral polypeptides in the immune response, and understanding the mechanism involved in virulence associated to adenovirus 7h.