Transmission of HTLV-I by blood transfusion and its prevention by passive immunization in rabbits

Abstract

To determine the minimum volume of blood required to transmit human T- cell leukemia virus type I (HTLV-I), heparinized blood was collected from a virus-infected female rabbit and aliquots of 10, 5, 1, 0.5, 0.1, and 0.01 mL were transfused into groups of two male rabbits each. All 10 rabbits transfused with 10 to 0.1 mL and 1 of 2 rabbits transfused with 0.01 mL seroconverted for HTLV-I after 2 to 4 weeks. HTLV-I- producing lymphoid cell lines of recipient origin were established from one seroconverted rabbit of each aliquot group. To determine the ability of passive immunization to protect against HTLV-I infection, two groups of three rabbits were first transfused with 5 mL of blood from the same virus-infected rabbit and then infused after 24 or 48 hours with 10 mL of HTLV-I immune globulin (77 mg/mL of IgG) prepared from seropositive healthy persons. None of the 24-hour immunization group seroconverted for HTLV-I during the observation period of six months; however, all of the 48-hour immunization group became seropositive after 2 to 4 weeks. These results indicate that HTLV-I can be transmitted with as little as 0.01 mL of virus-infected blood, and that passive immunization is effective in preventing cell-to-cell infection of HTLV-I when given within 24 hours of transfusion of virus- infected blood.

Analysis of HTLV‐1 proviral load (PVL) and antibody detected with various kinds of tests in Japanese blood donors to understand the relationship between PVL and antibody level and to gain insights toward better antibody testing

“…For instance, experiments indicated that passive immunization with an IgG fraction prepared from seropositive asymptomatic carriers prevented HTLV-1 transmission in rabbits. 25 Furthermore, there have been numerous reports of HTLV-1 for ATL development. It has been speculated that not only a high PVL but also male sex is a risk factor for ATL 20 ; however, a contribution of anti-HTLV-1 antibody to ATL development has rarely been described.…”

Transfusion transmission of retroviruses: human T‐lymphotropic virus types I and II compared with human immunodeficiency virus type 1

“…In an animal model, 0.01 mL of blood is sufficient to transmit HTLV-I from rabbit to rabbit. 26 The number of lymphocytes transferred in the experiment was estimated to be 1.7 x lo4. The same group of Japanese investigators has also found that HTLV-I can be transmitted to rabbits by human milk and semen containing an estimated -<6 x lo7 lymphocyte^.^^ HTLV-I transmission to a health care worker via needlestick has been and the large number of HTLV-I-and particularly HTLV-II-infected intravenous drug userszo suggests that the required dose of HTLV-I-and -11-infected lymphocytes for humans may be low.…”

Inhibitory effect of maternal antibody on mother‐to‐child transmission of human T‐lymphotropic virus type I

“…It is thus likely that neonatal infection with HTLV-I could also be prevented by the maternal antibody. This implication is supported by the evidence that HTLV-I infection of newborn rabbits was prevented by the passive transfer of an immune serum containing anti-HTLV-I IgG antibody (Takehara et al, 1989;Kataoka et aL, 1990).…”