Frequency and time course of seroconversion in maternal and infant transmission of HTLV-1 (abstract)

Objectives: To characterize the frequency and timecourse of seroconversion in infants acquiring HTLV-I infection from their mothers. Methods: 220 children born to HTLV-I seropositive women in Kingston, Jamaica were followed regularly for up to 36 months following birth. At each visit, mothers were interviewed and children were examined and blood samples taken. Results: A total of 30 children have seroconverted, including 17/86 (20 percent) of those completing >/= 24 months of follow-up. Analysis of serial Western blots (WB) on 7 seroconverters revealed maternal antibodies persisting for 7.3 months ([mean], [range 7.0 - 7.4]), followed by an absence of any antibody response lasting 8.3 months ([mean], [range 2.8 - 14.2]), followed by seroconversion (gag+env), occuring at 14.1 months ([mean], [range 9.8 - 21.5]). Six of these children were breast-feeding at the time of seroconversion and one had stopped breast feeding 8 months prior to seroconversion. Two mothers lacking gag antibody p24 on WB transmitted virus to their offspring. Conclusion: HTLV-I seroconversion in infants seems to occur only after the disappearance of maternal antibody, suggesting that this antibody may be protective, and raising the possibility that an HTLV-I vaccine could prevent transmission of virus. Current WB criteria that require presence of p24 antibody do not identify all individuals capable of transmitting HTLV-I

A prospective study of transmission by transfusion of HTLV-I and risk factors associated with seroconversion

To evaluate the risk of transfusion-related transmisssion of HTLV-I in Jamaica, a prospective study was initiated, prior to availability of a licensed HTLV-I serological screening assay. This information would prove useful in formulating strategies for blood-donor screening. We followed 118 pre-transfusion HTLV-I-negative transfusion recipients at monthly intervals post-transfusion for 1 year. Laboratory and questionnaire data were obtained at each visit to evaluate the clinical and immunological status of recipients. Cumulative incidence of HTLV-I seroconversion was estimated and risk-factor data associated with seroconversion among 66 HTLV-I-exposed transfusion recipients were analyzed. Seroconversion occurred in 24/54 (44 percent) of recipients of HTLV-I-positive cellular blood components, 0/12 recipients of positive non-cellular donor units and 0/52 recipients of HTLV-I-negative donor units. Significant risk factors associated with recipient seroconversion were receipt of a seropositive cellular blood component stored for less than one week odds ratio (OR) = 6.34, 95 percent confidence interval (CI) = 1.83 to 21.92], male sex (OR = 4.79, 95 percent CI = 1.15 to 20.0) or use of immunosuppressive therapy at time of transfusion (OR = 12.20, 95 percent CI = 0.95 to 156). Risk of blood-borne infection per person per year in Jamaica was estimated to be 0.009 percent. Our results confirm that blood transfusion carries a significant risk of HTLV-I transmission and that screening of donor blood effectively prevents HTLV-I seroconversion. Recipients at greatest risk for seroconversion were those who required multiple transfusions or who were receiving immunosuppressive therapy at the time of transfusion. These patients should be given priority in receiving selectively screened blood components, if universal blood-donor screening for HTLV-I is not possible (AU)

Perinatal transfusion transmission of HTLV-I: risk to mother and child - abstract

As part of a prospective study of transfusion-transmission of HTLV-I antibody (Ab) positive blood in the perinatal period. Pretransfusion seronegative recipients of HTLV-I-positive blood components were retrospectively identified and subsequently followed up monthly for six months and then semi-annually thereafter. At each visit, a questionnaire was administered, physical examination was done and blood was drawn to assess haematological and immunological status of recipients. Mothers who were transfused during pregnancy had their pregnancy outcome noted and where possible were followed up as mother/infant pairs. The outcome of subsequent pregnancies was noted. Thirty-nine subjects in our cohort of 66 were women and 21 of them were transfused during pregnancy or in the puerperium . Nineteen of these women received cellular HTLV-I Ab-positive blood products and two received acellular products. Nine of our 21 mothers who received HTLV-I-positive blood products seroconverted, yielding a seroconversion rate of 42 percent which is consistent with the overall cohort. Fourteen of the 21 pregnancies ended in viable children but two mother/infant pairs wre lost to follow-up. Of the 12 remaining mothers, 4 received transfusion antepartum (1 day to 15 weeks prior to delivery), while 8 were transfused either interpartum or up to three weeks post partum. All of the 12 mothers breastfed their babies for periods ranging from one week to four years (median duration of six months). Six of the 12 mothers were sreoconverters and 2 of the six children of these mothers have also seroconverted between one and two years following birth. This yields a mother/infant transmission rate of 33 percent which is more than the reported 20 percent rate in previous mother/infant studies. The difference, however, is not statistically significant. One seropositive child has developed Infective Dermatitis (ID), a recently described HTLV-I associated disorder. We conclude that, HTLV-1 transmission via blood transfusion to pregnant women poses a risk to mother and child. We propose that, where widespread screening for HTLV-antibodies is not feasible, screening of blood for transfusion in to pregnant mothers should be given priority as at least two individuals are at risk of infection and disease (AU)

Detection of early human T-cell lymphotropic virus type I antibody patterns during seroconversion among transfusion recipients

From a cohort of human T-cell lymphotropic virus type I (HTLV-I) exposed transfusion recipients (N=71) enrolled in the Jamaican Transfusion Study, 11 were selected for detailed laboratory evaluation. All recipients were followed at monthly intervals for 6 months and then bimonthly up to 1 year for evidence of HTLV-I seroconversion. Without regard to results on screening assays, pretransfusion and posttransfusion samples were tested with two licensed HTLV-I whole-virus screening enzyme immunoassays (EIAs), recombinant EIAs for antibody against tax (p40x) and p21e envelope, standard whole virus Western blot (WB), WB enhanced with recombinant p21e, and radioimmunoprecipitation assay (RIPA). In the early period post transfusion, antibody to gag core protein was predominant with anti-p24 generally appearing before anti-p19. Recombinant anti-p21e envelope protein, in EIA and WB format, was frequently the earliest envelope reactively detected, while anti-gp46 in WB and anti-gp61/68 in RIPA system appeared later. Anti-tax antibodies appeared later in the time course of seroconersion. The whole-virus EIAs were less sensitive than the confirmatory assays. The combination of WB and RIPA or WB enhanced with recombinant p21e appeared equally effective in confirming samples as positive by the Public Health Service two gene group confirmatory algorithm. However specificity of this assay approach could not be addressed in this study.(AU)