Variability and recombination of clinical human cytomegalovirus strains from transplantation recipients

Abstract

Background: Human cytomegalovirus (HCMV) is the first cause of viral infection in immunocompromised transplanted patients.

Objectives: Here, five HCMV genes were studied to investigate the existence of recombination events in clinical strains ex vivo.

Study design: Sequencing and phylogenetic analysis were conducted on 21 strains from 16 renal and 5 lung transplant recipients.

Results: Nucleotidic polymorphism ranged from 6.6% (US3) to 12% (UL40), with a significant proportion of missense mutations (39-69%), some of which could have a functional impact. Analysis of the concatenated sequence (4804 nucleotides for each strain) evidenced two clusters of sequences presenting a reticulate topology suggestive of recombination events (SplitsTree). Phi-test pointed numerous phylogenetically conflicting signals indicating a high statistical probability of recombination. The subsequent bootscan analysis was consistent with these data.

Conclusions: These results reinforce the prominent role of recombination in HCMV evolutionary history and adaptation to its host.