HIV-1 subtypes detected during 1991-March 1999 in Japan
(IASR 2000; 21: 141-142)

To date Human Immunodeficiency Virus (HIV)-1 is classified in 12 subtypes including group M (A, B, C, D, E, F, G, H, I, J), group N, and group O by RNA sequence pattern. Subtype B was used to be isolated as the major strain in Japan, but subtype E has been increasing recent years, especially infections due to heterosexual contact. In addition, subtype A and C, although number of isolation remains small, have been reported recently.

In order to clarify recent trends of HIV-1 infections, RNA subtyping was carried out using 298 specimens (peripheral blood monocyte, serum), which were referred to the Kanagawa Prefectural Institute of Public Health during 1991 to March 1999.

Analysis of specimens from the subtype B and E endemic areas (e.g. Japan, North America, Southeast Asia), polymerase chain reaction (PCR) for subtype B and E primers and enzyme-linked immunosorbent assay (ELISA) for env V3 region peptide were carried out. If specimens were unclassified with above methods, or specimens from other than the subtype B and E endemic areas (e.g. Africa), these specimens were first analyzed for RNA sequence of the env C2V3 region, and then subtype was classified by dendrogram analysis using neighbor-joining method.

Twenty-eight specimens from hemophiliac patients, who were medicated tainted blood products containing anticoagulant factors, were all classified as subtype B. One Latin American specimen, which intravenous drug abuse was suspected as cause of infection, was classified as subtype F. Seventy-three out of 75 specimens from homosexual persons were classified in subtype B. The rest were classified in subtype A and E.

One hundred ninety-four specimens from heterosexual persons were classified in subtype E (134), B (39), A (10), C (7), D (3), and G (1). Of 194 heterosexual persons, 86 were Japanese, and 108 were foreigners including Southeast Asian (92), African (11), Latin American (4), North American (1). Japanese specimens were classified in subtype E (43), B (31), A (6), D (3), C (2), and G (1). Foreign specimens were classified in subtype E (91), B (8), C (5), and A (4).

In order to find recombinant virus, not only the env region but the gag p24 region were also analyzed for some African specimens. Only one specimen of a Tanzanian person showed subtype A in the env region and subtype C in the gag p24 region. To rule out double infection, RNA sequence between gag and pol (pro-RT) was analyzed. Then this specimen was turned out to be a recombinant virus.

Reported by: Makiko Kondo and Mitsunobu Imai, Kanagawa Prefectural Institute of Public Health

Correspondence: Mitsunobu Imai;
E-mail: imaim@d2.dion.ne.jp
Fax: +81-45-363-1037

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