Natural history of the retrovirus associated with a human leukemia

Dental variation of Ryukyu islanders: a comparative study among Ryukyu, Ainu, and other Asian populations

The presence or absence of 24 nonmetric dental traits was examined to investigate the inter- and intraregional variation of Ryukyu Islanders. We compared the dentition of the Kadena sample from the central district of Okinawa Island in the Ryukyu Island chain to those of samples from Nakijin from the northern district of the same Okinawa Island, Tokunoshima, another island of the Ryukyu Island chain, main-island Japanese in Kagoshima and Tokyo, Hokkaido Ainu, Atayal in Taiwan, and Pashtuns and Tajiks in Afghanistan. Many traits of the Ryukyu Islanders were found to be close to those of the main-island Japanese; however, several were intermediate between those of the main-island Japanese and the Ainu or Atayal. The intraregional variation in the Ryukyu Islanders was comparable to that in the main-island Japanese. This result supports the influence of a complex gene flow to the Ryukyu Islanders, as suggested by some genetic studies. Among the populations compared here, that closest to the Ainu was the population of Tokunoshima.

Seroprevalence of human T-lymphotropic virus type 1 in Papua New Guinea and Irian Jaya measured using different western blot criteria

BACKGROUND

Endemic foci of HTLV-1 carriers have been found in the world, however, the origin of HTLV-1 in humans is still unclear. Since a distinct type of virus strain was isolated from the Solomon Islands, detailed surveys on HTLV-1 prevalence in New Guinea are important to shed light on its history of dissemination.

OBJECTIVE

To clarify the seroprevalence of HTLV-1 in different regions of New Guinea Island.

STUDY DESIGN

Sera from 1221 individuals (649 males, 454 females and 118 unknown) in New Guinea Island were studied for the presence of antibodies to HTLV-1 by a particle agglutination and the Western blot (WB) tests. Two different sets of criteria, proposed by WHO and Kiyokawa et al., were employed to interpret the WB test. Since the latter seemed to lack adequate specificity, the WHO criteria was used for the evaluation of the seroprevalence throughout the study.

RESULTS

Seroprevalence of HTLV-1 differed by the WB criteria. By the more stringent criteria, HTLV-1 carriers were found in Madang, Chimbu and one hinterland province, Enga, in Papua New Guinea. An overall seroprevalence rate in different regions ranged from 0 to 14.6%. No seropositive individuals were found in Irian Jaya.

CONCLUSIONS

To avoid overestimating the seropositivity rates, the WHO criteria would be more appropriate to employ for WB test by using the samples obtained from tropical and/or malaria endemic areas. This study is the first to show HTLV-1 infected individuals in the hinterland of New Guinea Island.

Is screening of Australian blood donors for HTLV-I necessary?

OBJECTIVE

To re-examine the 1992 decision by Australian Red Cross for its blood banks to screen blood donors for antibody to human T-cell lymphotropic virus type I (HTLV-I) by determining the risk of its transmission by blood transfusion.

METHODS

Data on patterns of return behaviour by repeat blood donors in Victoria were modelled to deduce the number of donors giving repeat donations in Australia from March 1993 to December 1995. Data on annual donor and issued cellular blood products from 1992 to 1995 were obtained from national Red Cross statistics. From the numbers of donations given by repeat donors, together with the number of new donors, the number tested for HTLV-I was deduced. The number and characteristics of donors screened positive for HTLV-I antibody were collated. The crude prevalence of HTLV-I was calculated by dividing the number of donors with HTLV-I by the total number of donors (repeat donors and new donors). The incidence of HTLV-I was calculated by dividing the number of seroconversions in repeat donors by the cumulative period of donor exposure.

RESULTS

Sixteen homologous and five autologous donors were found to be positive for HTLV-I; none seroconverted and no clear risk factors for HTLV-I were identified. The prevalence of HTLV-I in Australian donors is 1 in 100,000 and the incidence less than 1 in 1 million person-years. In the absence of HTLV-I screening, the calculated risk of a transfused patient developing HTLV-I infection is 1 in 370,000, with a risk of developing HTLV-I disease of 1 in 9 to 15 million.

CONCLUSION

Three possible future courses of action for screening for HTLV-I are to screen every donation, to screen only new donors or to discontinue screening altogether. Using the information in this study, public discussion should be encouraged to assist stakeholders to agree on an acceptable level of risk and an appropriate level of screening for HTLV-I in Australia.

Identification of membrane antigen C33 recognized by monoclonal antibodies inhibitory to human T-cell leukemia virus type 1 (HTLV-1)-induced syncytium formation: altered glycosylation of C33 antigen in HTLV-1-positive T cells

We isolated four monoclonal antibodies (MAbs), M38, M101, M104, and C33, which were capable of inhibiting syncytium formation induced in a human T-cell line, MOLT-4-#8, by coculture with human T-cell leukemia virus type 1 (HTLV-1)-positive human T-cell lines. The MAbs had, however, no inhibitory activity on syncytium formation induced in a human osteosarcoma line, HOS, by HTLV-1-positive T-cell lines. They also did not inhibit syncytium formation induced in MOLT-4-#8 by human immunodeficiency virus type 1-positive MOLT-4. All MAbs reacted with various human cell lines of lymphoid and nonlymphoid origins, including HTLV-1-positive T-cell lines. Furthermore, they all reacted with a murine A9 clone containing human chromosome 11 fragment q23-pter. Two MAbs, M104 and C33, immunoprecipitated a membrane antigen with the same molecular size. The antigen (henceforth called C33 antigen) was about 40 to 55 kDa in HTLV-1-negative Jurkat, CEM, MOLT-4, and normal peripheral blood CD4-positive human T cells and about 40 to 75 kDa in HTLV-1-positive C91/PL, TCL-Kan, MT-2, and in fresh HTLV-1-transformed CD4-positive human T-cell lines. Pulse-chase experiments revealed that C33 antigen was synthesized as a 35-kDa precursor that was then processed to 41 to 50 kDa in MOLT-4 and to 44 to 70 kDa in C91/PL. In the presence of tunicamycin, a 28-kDa protein was synthesized. The conversion from 35 kDa to 41 to 50 kDa in MOLT-4 and to 44 to 70 kDa in C91/PL was inhibited by monensin. Treatment with N-glycanase alone, but not with sialidase and O-glycanase in combination, completely removed the sugar moiety of C33 antigen from both HTLV-1-negative Jurkat and HTLV-1-positive C91/PL. Therefore, C33 antigen has only N-linked carbohydrates, the modification of which appears to be substantially altered in the presence of the HTLV-1 genome.

Seroepidemiologic survey for antibodies to human retroviruses in human and non-human primates in Brazil

The prevalence of antibodies to HTLV-I and HIV-I in Brazil was determined by testing sera from: (a) 119 members of an isolated Amazonian community of African origin; (b) 100 voluntary blood donors in Rio de Janeiro; (c) 215 patients treated at the Hematology Service, National Cancer Institute, Rio de Janeiro, and (d) 44 Cebus apella New World monkeys, wild-caught in Amazonia. Anti-HTLV-I was detected in 1 (0.84%) of 119 Amazonians, in 8 (3.72%) of the 215 patients and in none of the blood donors or monkeys. The high prevalence found in patients included 4 (5.79%) of 69 with non-Hodgkin lymphoma, 2 (5.88%) of 34 with Hodgkin lymphoma, 1 (16.66%) of 6 patients with diagnosis of anemia and 1 (20%) of 5 with HIV-I infection. Anti-HIV-I was found in 7 (14.89%) of 47 patients and in none of the other groups. The high incidence of HTLV-I infection in the patient group suggests that this retrovirus is endemic in parts of Brazil.