Background: Respiratory syncytial virus (RSV) is the leading cause of serious lower tract infections in infants. Comorbid conditions such as chronic diseases and prematurity have been associated with greater severity illness, but virus genotypes and disease severity is still unknown.
Methods: Forty selected strains of RSV group A and B from Cuban infants with acute respiratory disease (ARD) over five seasons were studied. Viral RNA was extracted and polymerase chain reaction (PCR) was carried out using direct primers directed to parts of the nucleoprotein (N) and fusion (F) genes, respectively. Amplicons were digested using restriction fragment length polymorphism (RFLP) to define the association between virus and disease severity. Disease severity was assessed as very mild, mild, moderate, and severe.
Results: Three of six known N genotypes were detected. NP4 and NP3 were found more frequently; moreover, it was difficult to establish a relationship between N genotypes and disease severity. Five genotypes in F gene were found: F1, F2, F5, F9 and F11; F9 and F11 were associated with very mild disease, but F1 genotype appears to be associated with moderate to severe disease.
Conclusions: At least five combinations of N and F genotypes circulated in the studied infants in Cuba. Patients with F1NP4 genotype showed moderate to severe disease. Relationship between genotypes and disease severity was established.