Genotype Distribution of Hepatitis C Virus in São Paulo, Brazil: Rare Subtype Found

To the Editor:

Genotypes 1, 2, and 3 of the hepatitis C virus (HCV) are widely distributed throughout Western countries and the Far East (Japan, China, Taiwan, Thailand). Types 5 and 6 are mainly confined to South Africa and Southeast Asia, respectively, in contrast to type 4, which is predominant in the Middle East and Central Africa.^1-3

To investigate the prevalence and distribution of HCV genotypes in Brazil, 348 subjects from four different populations were studied: 34 anti-HCV-positive blood donors, 23 hemophiliacs, 40 renal-transplant recipients, and 251 chronic hepatitis C (CH-C) patients. HCV genotyping was performed in serum samples of 239 (95%) out of 251 CH-C patients and of all blood-donor and hemophiliac samples by a reverse hybridization assay (Line Probe Assay - INNO-LiPA HCV or INNO-LiPA HCV II, second generation, Innogenetics, Ghent, Belgium), in which a reverse transcriptase-polymerase chain reaction (RT-PCR) product of the 5'untranslated region (5'UTR) is hybridized with probes from various HCV genotypes.² Twelve samples, of the 251 sera from the CH-C patients, and all from the renal-transplant patients were tested by a serotyping assay (HCV Serotyping Assay 1-6, Murex Diagnostics, Dartford, UK).²

The genotyping results of the 348 HCV isolates, on the basis of the line probe and/or serotyping assays, are shown in Table 1. Four different types were found, and their overall prevalence was 63% for type 1, 4.3% for type 2, 31.3% for type 3, and 0.3% for type 4. Four subjects revealed mixed infections: two cases within types (1a + 1b in a renal-transplant recipient and 2a + 2b in a CH-C patient), and two cases across types (1b + 3a in a blood donor and in a CH-C patient). A similar distribution was observed for each of the four populations, as a general rule; the exceptions were genotypes 2 for the renal-transplant recipients and 3 for the hemophiliacs, whose frequencies were found to be approximately double (13%) and half (15%), respectively, their values in the other populations.

View this table:

Table 1. Prevalence of HCV Genotypes and Their Distribution in Various Populations of São Paulo, Brazil

Data available from other Brazilian regions, showed corroborating figures for 114 blood donors in Rio de Janeiro, Southeast (1a, 42%; 1b, 34%; and 3a, 20%),² and for 100 CH-C patients in Porto Alegre, South (type 1, 55%; and type 3, 37%).⁴ Moreover, as it is known, the current screening assays are based on epitopes derived from only genotypes 1a or 1b, causing variation in seroreactivity among different HCV genotypes.^5,6 Therefore, the high prevalence hereby reported not only for genotypes 1a and 1b, but for others (3 in particular) should be of main concern and of much interest for research and development of serological screening assays.

Finally, we have identified in a renal-transplant patient an unpublished genotype in Brazil: the 4a.

Leda Bassit, M.Sc.
Gabriela Ribeiro-Dos-Santos, Ph.D.
Luiz C. Da Silva, M.D., Ph.D.
Kioko Takei, Ph.D.
Paula Villaça, M.D., Ph.D.
Elias David-Neto, M.D., Ph.D.
Dalton Chamone, M.D., Ph.D.
Amadeo Sáez-Alquézar, M.Sc.
¹Pharmaceutical Sciences and Medical Schools
of the Unversity of São Paulo
²Fundação Pró-Sangue Hemocentro de São Paulo
³Tropical Medicine Institute, São Paulo, Brazil

REFERENCES

1.	McOmish F, Yap PL, Dow BC, Follett EAC, Seed C, Keller AJ, Cobain TJ, et al. Geographical distribution of hepatitis C virus genotypes in blood donors: an international collaborative survey. J Clin Microbiol 1994;32:884-892.
2.	Maertens G, Stuyver L. Genotypes and genetic variation of hepatitis C virus. In: Harrison TJ, Zuckerman AJ (eds). The Molecular Medicine of Viral Hepatitis. England: Wiley, 1997:183-233.
3.	Gish RG, Lau JYN. Hepatitis C virus: eight years old. Viral Hep Rev 1997;3:17-37.
4.	Krug LP, Lunge VR, Ikuta N, Fonseca AS, Cheinquer H, Ozaki LS, Barros SG. Hepatitis C virus genotypes in Southern Brazil. Braz J Med Biol Res 1996;29:1629-1632.
5.	Dhaliwal SK, Prescott LE, Dow BC, Davidson F, Brown H, Yap PL, Follett EA, et al. Influence of viraemia and genotype upon serological reactivity in screening assays for antibody to hepatitis C virus. J Med Virol 1996;48:184-190.
6.	Mison LM, Young IF, O'Donoghue M, Cowley N, Thorlton N, Hyland CA. Prevalence of hepatitis C virus and genotype distribution in an Australian volunteer blood donor population. Transfusion 1997;37:73-78.

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