Genetic variability of hepatitis A virus isolates in Rio de Janeiro: implications for the vaccination of school children

Abstract

The epidemiology of hepatitis A virus (HAV) infection is shifting from high to intermediate endemicity in Brazil, resulting in increased numbers of susceptible individuals and a greater potential for the emergence of outbreaks. Universal vaccination against HAV has been recommended for children, but updated sero-epidemiological data are necessary to analyze the level of natural immunity and to identify candidates for preventive measures. In addition, more molecular studies are necessary to characterize the genotypes involved in HAV infections and outbreaks. Sera from 299 school children (5-15 years old) and 25 school staff members, collected during an outbreak of HAV at a rural public school in June 2000, were tested for IgM and total anti-HAV antibodies (ELISA). Viral RNA was amplified by RT-PCR from anti-HAV IgM-positive sera and from 19 fecal samples. Direct nucleotide sequencing of the VP1/2A region was carried out on 18 PCR-positive samples. Acute HAV infection was detected by anti-HAV IgM in 93/299 children and in 3/25 adult staff members. The prevalence of total anti-HAV antibodies in IgM-negative children under 5 years of age was only 10.5%. HAV-RNA was detected in 46% IgM-positive serum samples and in 16% stool samples. Sequence analysis showed that half the isolates belonged to subgenotype IA and the other half to IB. On the basis of these data, mass vaccination against HAV is recommended without prevaccination screening, especially for children before they enter school, since nearly 90% of the children under 5 years were susceptible. Molecular characterization indicated the endemic circulation of specific HAV strains belonging to subgenotypes IA and IB.

Prevalence of hepatitis A virus infection in Goiânia, Goiás, Brazil, by molecular and serological procedures, 1995-2002

“…HAV RNA was detected in 54.5% of the fecal samples, which is consistent with the results of other studies (Skinhoj et al 1981, Yotsuyanagi et al 1996, Villar et al 2004. On the other hand, it was observed that this rate was significantly greater considering serum samples.…”

Early infection and asymptomatic spread of hepatitis A virus in a public child care center in Rio de Janeiro, Brazil: should attending children under two years of age be vaccinated?

“…Using molecular analysis, we detected the co-circulation of subgenotypes IA and IB, which corroborates the findings of other studies conducted in Rio de Janeiro , Villar et al 2004. The co-circulation of two subgenotypes suggests the existence of more than one source of infection.…”

“…Prevalent human strains fall into genotypes I or III, each of which are divided into subtypes A and B. In Brazil, co-circulation of subgenotypes IA and IB have been found in Rio de Janeiro , Villar et al 2004. Circulation of subgenotype IA has also been detected in other regions of Brazil (de Paula et al 2004).…”

Molecular characterization of hepatitis A virus isolates from Goiânia, Goiás, Brazil

“…This demonstrates that a genotype I infection has an endemic character in Brazil, although it is the only South American country in which the circulation of both subgenotypes IA and IB has been reported (de Paula et al 2002, Devalle et al 2003, Villar et al 2004. However, this study differs from that of de , in which the analysis of the nucleotide sequence of the VP1/2A junction region showed the occurrence of only subgenotype IA in isolates from the state of Goiás.…”

“…In Brazil, the only genotype that has been found is genotype I, especially subgenotype IA ). However, subgenotype IB has also been observed to circulate in the states of Rio de Janeiro and Pernambuco and in the Amazon region (de Paula et al 2002, Devalle et al 2003, Villar et al 2004.…”