Characteristics of Persons Who Inject Drugs with Recent HIV Infection in the United States: National HIV Behavioral Surveillance, 2012.

We evaluated characteristics associated with recent HIV infection among persons who inject drugs (PWID) from 19 U.S. cities who participated in 2012 National HIV Behavioral Surveillance. Recent infection was defined as having a reactive HIV test, a Bio-Rad Avidity index cutoff ≤ 30%, no reported HIV diagnosis ≥ 12 months before interview, and no evidence of viral suppression. Of 8667 PWID, 50 (0.6%) were recently HIV infected. Having a greater number of sex partners (≥ 2 partners vs. 0) [prevalence ratio (PR) 4.7, 95% confidence interval (CI) 1.3-17.8], injecting heroin and other drugs (PR 3.0, 95% CI 1.3-6.6) or exclusively non-heroin drugs (PR 5.9, 95% CI 1.7-20.7) compared to injecting only heroin, and having male-male sex in the past year (PR 7.1, 95% CI 3.0-16.6) were associated with recent infection. Promoting not only safe injection practices but also safe sex practices will be key to preventing new HIV infections.

New multiple antigenic peptide-based enzyme immunoassay for detection of simian immunodeficiency virus infection in nonhuman primates and humans.

Infections with human immunodeficiency virus types 1 and 2 (HIV-1 and HIV-2, respectively) are zoonotic infections. In Africa, the potential exists for additional cross-species transmissions from at least 33 different species of simian immunodeficiency virus (SIV)-infected nonhuman primates (NHPs) through hunting and butchering of these animals for food. Here we describe a highly sensitive and specific enzyme immunoassay (EIA) with chemically modified, multiple antigenic peptides (MAPs) developed for the detection and discrimination of antibodies to SIV genetic lineages. The SIV EIA was developed by using a comprehensive array of MAPs covering two envelope gene regions from all of the SIV lineages for which env sequences were available. Assay sensitivity was evaluated by using 63 plasma or serum samples obtained from primates naturally or experimentally infected with SIVs from 10 genetic lineages. Assay specificity was determined by using 97 known SIV-negative plasma specimens from these same species. Also used in the evaluations were 369 human samples: 198 HIV seronegative, 170 HIV-1 and/or HIV-2 seropositive, and 1 from a human SIVsm infection. Overall assay sensitivity and specificity were 100% with both immunodominant region (IDR) and V3 region MAPs. Although SIV env sequences from talapoin monkeys were not available for specific MAP inclusion, 5 (100%) of 5 SIVtal-infected samples were detected through cross-reactivity with other SIV IDR MAPs used in the assay. The one human SIVsm infection was identified. In conclusion, our SIV MAP EIA proved to be highly sensitive and specific for detecting SIV infections in NHPs and humans. As shown with SIV-infected talapoin monkeys, this assay has the potential to detect previously unidentified SIV strains and should be suitable for sentinel surveillance for potential new cross-species transmissions of SIVs to humans.

Simian foamy virus infection in a blood donor.

BACKGROUND: Infections with simian foamy virus (SFV) are widely prevalent in nonhuman primates. SFV infection was confirmed in a worker, occupationally exposed to nonhuman primates, who donated blood after the retrospectively documented date of infection. Human-to-human transmission of SFV through transfusion and its pathogenicity have not been studied. STUDY DESIGN AND METHODS: Recipients of blood from this donor were identified and blood samples from such recipients were tested for SFV infection by Western blot and PCR assay. RESULTS: One recipient of RBCs and another recipient of FFP had died; retroviral infections were not implicated. One platelet recipient could not be tested. Recipients of RBCs (two), a WBC-reduced RBC unit (one), and a platelet unit (one) tested SFV-negative 19 months to 7 years after transfusion. Tested recipients had transfusions 3 to 35 days after blood donation. Samples of one lot of albumin and three lots of plasma protein fraction (manufactured from recovered plasma from two donations) tested negative both for antibodies and for viral RNA. CONCLUSION: SFV transmission through transfusion was not identified among four recipients of cellular blood components from one SFV-infected donor. Derivatives containing plasma from that donor tested negative for SFV.

Lack of cross-species transmission of porcine endogenous retrovirus infection to nonhuman primate recipients of porcine cells, tissues, or organs.

BACKGROUND: Nonhuman primates (NHPs) have been widely used in different porcine xenograft procedures inevitably resulting in exposure to porcine endogenous retrovirus (PERV). Surveillance for PERV infection in these NHPs may provide information on the risks of cross-species transmission of PERV, particularly for recipients of vascularized organ xenografts for whom data from human clinical trials is unavailable. METHODS: We tested 21 Old World and 2 New World primates exposed to a variety of porcine xenografts for evidence of PERV infection. These NHPs included six baboon recipients of pig hearts, six bonnet macaque recipients of transgenic pig skin grafts, and nine rhesus macaque and two capuchin recipients of encapsulated pig islet cells. Serologic screening for PERV antibody was done by a validated Western blot assay, and molecular detection of PERV sequences in peripheral blood mononuclear cells (PBMCs) and plasma was performed using sensitive polymerase chain reaction and reverse transcriptase-polymerase chain reaction assays, respectively. Spleen and lymph node tissues available from six bonnet macaques and three rhesus macaques were also tested for PERV sequences. RESULTS: All plasma samples were negative for PERV RNA suggesting the absence of viremia in these xenografted animals. Similarly, PERV sequences were not detectable in any PBMC and tissue samples, arguing for the lack of latent infection of these compartments. In addition, all plasma samples were negative for PERV antibodies. CONCLUSION: These data suggest the absence of PERV infection in all 23 NHPs despite exposure to vascularized porcine organs or tissue xenografts and the use of immunosuppressive therapies in some animals. These findings suggest that PERV is not easily transmitted to these NHP species through these types of xenografts.

Lack of evidence of endogenous avian leukosis virus and endogenous avian retrovirus transmission to measles, mumps, and rubella vaccine recipients.

The identification of endogenous avian leukosis virus (ALV) and endogenous avian retrovirus (EAV) in chick cell-derived measles and mumps vaccines in current use has raised concern about transmission of these retroviruses to vaccine recipients. We used serologic and molecular methods to analyze specimens from 206 recipients of measles, mumps, and rubella (MMR) vaccine for evidence of infection with ALV and EAV. A Western blot assay for detecting antibodies to endogenous ALV was developed and validated. All serum samples were negative for antibodies to endogenous ALV by Western blot analysis. Peripheral blood lymphocyte samples from 100 vaccinees were further tested by polymerase chain reaction for both ALV and EAV proviral sequences; all were negative. Matching serum samples were tested by reverse transcriptase polymerase chain reaction for ALV and EAV RNA, and all 100 samples were negative, providing no evidence of viremia. These findings do not indicate the presence of either ALV or EAV infection in MMR vaccine recipients and provide support for current immunization policies.

Evidence of infection with simian type D retrovirus in persons occupationally exposed to nonhuman primates.

Simian type D retrovirus (SRV) is enzootic in many populations of Asian monkeys of the genus Macaca and is associated with immunodeficiency diseases. However, the zoonotic potential of this agent has not been well defined. Screening for antibodies to SRV was performed as part of an ongoing study looking for evidence of infection with simian retroviruses among persons occupationally exposed to nonhuman primates (NHPs). Of 231 persons tested, 2 (0.9%) were found to be strongly seropositive, showing reactivity against multiple SRV antigens representing gag, pol, and env gene products by Western immunoblotting. Persistent long-standing seropositivity, as well as neutralizing antibody specific to SRV type 2, was documented in one individual (subject 1), while waning antibody with eventual seroreversion was observed in a second (subject 2). Repeated attempts to detect SRV by isolation in tissue culture and by using sensitive PCR assays for amplification of two SRV gene regions (gag and pol) were negative. Both individuals remain apparently healthy. We were also unable to transmit this seropositivity to an SRV-negative macaque by using inoculation of whole blood from subject 1. The results of this study provide evidence that occupational exposure to NHPs may increase the risk of infection with SRV and underscore the importance of both occupational safety practices and efforts to eliminate this virus from established macaque colonies.

Evidence of porcine endogenous retroviruses in porcine factor VIII and evaluation of transmission to recipients with hemophilia.

Since 1984, unheated porcine clotting factor VIII (Hyate:C) has been used to treat severe bleeding episodes in persons with hemophilia who have antibodies to human clotting factor. We document the presence of porcine endogenous retrovirus (PERV) in plasma samples of pigs and in clinical lots of Hyate:C. Both gag and pol PERV RNA sequences were detected by reverse-transcriptase (RT) polymerase chain reaction in 13 of 13 lots of Hyate:C tested. Among 10 of these lots, RT activity also was detected, which confirms the presence of retroviral particles. To assess the transmission of PERV to Hyate:C recipients, we tested serum specimens from 88 recipients of Hyate:C and 23 noninfused control subjects for anti-PERV antibodies by using a Western blot assay. None of the samples was positive. Our data document that PERV particles are a common contaminant of Hyate:C products and suggest that the risk of PERV transmission from these percutaneous exposures is very low.

Absence of evidence of infection with divergent primate T-lymphotropic viruses in United States blood donors who have seroindeterminate HTLV test results.

BACKGROUND: Recent identification of divergent simian or primate T-lymphotropic viruses (STLVs; PTLVs) in bonobos (formerly called pygmy chimpanzees; Pan paniscus; viruses: STLVpan-p and STLVpp1664) and a baboon (Papio hamadryas; viruses: STLVph969 or PTLV-L) have raised the possibility of human infection with these viruses. Divergent PTLV-infected primate sera show p24 bands on HTLV-I Western blots (WBs). It was investigated whether infection by divergent PTLV-like viruses could explain a subset of United States blood donors who reacted on HTLV-I EIAs and had indeterminate HTLV-I WBs with p24 bands. STUDY DESIGN AND METHODS: Epidemiologic characteristics of 1889 donors with HTLV-I-indeterminate WBs were compared to those of donors with confirmed retrovirus infections (393 with HIV, 201 with HTLV-I, 513 with HTLV-II) and 1.6 million donors with nonreactive screening tests. To directly probe for infection with divergent PTLVs, 2 HTLV-I-indeterminate donors born in Africa and 269 representative non-African-born donors with p24 bands on HTLV-I WBs (previously shown to be negative for HTLV-I and -II DNA by PCR) were selected for PTLV PCR analysis. DNA from peripheral blood MNC samples was tested for a proviral tax sequence by PCR using generic primers that amplify HTLV-I, HTLV-II, and the divergent PTLVs. Amplified tax sequences were detected by Southern blot hybridization to a (32)P-labeled generic PTLV probe. PCR-positive samples could then be typed by hybridization with virus-specific internal probes that differentiate HTLV-I, HTLV-II, PTLV-L, and STLVpan-p. RESULTS: In the epidemiologic analysis, HTLV-indeterminate status was independently associated with age of at least 25 years (OR = 2.19; 95% CI, 1.93-2.49), black (OR = 3.27; 95% CI, 2.90-3.67) or Hispanic (OR = 1.82; 95% CI, 1.52-2.16) race or ethnicity, and donation at one blood center (Baltimore) (OR = 1. 30; 95% CI, 1.11-1.53). None of the 271 HTLV-I WB-indeterminate samples tested positive by generic PTLV PCR analysis. CONCLUSION: Although the epidemiologic data suggest the possibility of undiagnosed HTLV-I, HTLV-II, or a cross-reactive virus such as PTLV among older, black, and Hispanic blood donors, the PCR data do not support the presence of divergent PTLV infection among US blood donors with HTLV-I-indeterminate results.

Simian foamy virus infection among zoo keepers.

We investigated 322 North American zoo workers in an anonymous serosurvey for antibodies to simian foamy viruses to establish the potential risk of zoonotic transmission by these retroviruses. 4 of 133 (3%) individuals who worked specifically with mammals including primates were seropositive, primarily with chimp-like viruses, indicating the importance of work practices to reduce exposure to these agents.

Persistent zoonotic infection of a human with simian foamy virus in the absence of an intact orf-2 accessory gene.

Although foamy viruses (FVs) are endemic among nonhuman primates, FV infection among humans is rare. Recently, simian foamy virus (SFV) infection was reported in 4 of 231 individuals occupationally exposed to primates (1.8%). Secondary transmission to spouses has not been seen, suggesting that while FV is readily zoonotic, humans may represent dead-end hosts. Among different simian species, SFV demonstrates significant sequence diversity within the U3 region of the long terminal repeat (LTR) and 3' accessory open reading frames (ORFs). To examine if persistent human SFV infection and apparent lack of secondary transmission are associated with genetic adaptations in FV regulatory regions, we conducted sequence analysis of the LTR, internal promoter, ORF-1, and ORF-2 on a tissue culture isolate and peripheral blood mononuclear cell samples from a human infected with SFV of African green monkey origin (SFV-3). Compared to the prototype SFV-3 sequence, the LTR, internal promoter, and FV transactivator (ORF-1) showed sequence conservation, suggesting that FV zoonosis is not dependent on host-specific adaptation to these transcriptionally important regions. However, ORF-2 contains a number of deleterious mutations predicted to result in premature termination of protein synthesis. ORF-2 codes in part for the 60-kDa Bet fusion protein, proposed to be involved in the establishment of persistent cellular SFV infections. These results suggest that persistent human infection by SFV and reduced transmissibility may be influenced by the absence of a functional ORF-2.

Polymerase chain reaction assays for the diagnosis of infection with the porcine endogenous retrovirus and the detection of pig cells in human and nonhuman recipients of pig xenografts.

BACKGROUND: Pigs offer an unlimited source of xenografts for humans. However, recipients of pig xenografts are inevitably exposed to the porcine endogenous retrovirus (PERV), which is carried in the pig germline. The ability of PERV to infect human cells in vitro has heightened safety concerns regarding the transmission of PERV to pig xenograft recipients. METHODS: In response to the need to establish laboratory tests for the surveillance of PERV infection, we have developed polymerase chain reaction (PCR) assays to detect PERV pol and gag sequences by using conserved primers and probes. In addition, we have developed a PCR assay to detect pig-specific mitochondrial DNA (mtDNA) sequences as a marker of pig cells. RESULTS: Analysis of assay sensitivities using cloned target copies in a background of human DNA demonstrated a detection threshold of 1, 5, and 1 copy for the PERV gag, pol, and pig mtDNA PCR assays, respectively. All three PCR assays gave negative results on peripheral blood lymphocyte samples from 69 humans, as well as 6 baboons and 6 macaques, demonstrating 100% specificity. The PERV and pig mtDNA assays were integrated into a simple testing algorithm that allows the differentiation between pig cell microchimerism and true xenogeneic infection. To allow for monitoring of PERV expression, a reverse transcriptase-PCR assay was also developed to detect cell-free PERV RNA. CONCLUSION: The use of the diagnostic tests described here will help define the risks of PERV transmission associated with the use of pig xenografts in humans and nonhuman primates.

Search for cross-species transmission of porcine endogenous retrovirus in patients treated with living pig tissue. The XEN 111 Study Group.

Pig organs may offer a solution to the shortage of human donor organs for transplantation, but concerns remain about possible cross-species transmission of porcine endogenous retrovirus (PERV). Samples were collected from 160 patients who had been treated with various living pig tissues up to 12 years earlier. Reverse transcription-polymerase chain reaction (RT-PCR) and protein immunoblot analyses were performed on serum from all 160 patients. No viremia was detected in any patient. Peripheral blood mononuclear cells from 159 of the patients were analyzed by PCR using PERV-specific primers. No PERV infection was detected in any of the patients from whom sufficient DNA was extracted to allow complete PCR analysis (97 percent of the patients). Persistent microchimerism (presence of donor cells in the recipient) was observed in 23 patients for up to 8.5 years.

Evidence of avian leukosis virus subgroup E and endogenous avian virus in measles and mumps vaccines derived from chicken cells: investigation of transmission to vaccine recipients.

Reverse transcriptase (RT) activity has been detected recently in all chicken cell-derived measles and mumps vaccines. A study of a vaccine manufactured in Europe indicated that the RT is associated with particles containing endogenous avian retrovirus (EAV-0) RNA and originates from the chicken embryonic fibroblasts (CEF) used as a substrate for propagation of the vaccine. We investigated the origin of RT in measles and mumps vaccines from a U.S. manufacturer and confirm the presence of RT and EAV RNA. Additionally, we provide new evidence for the presence of avian leukosis virus (ALV) in both CEF supernatants and vaccines. ALV pol sequences were first identified in particle-associated RNA by amplification with degenerate retroviral pol primers. ALV RNA sequences from both the gag and env regions were also detected. Analysis of hypervariable region 2 of env revealed a subgroup E sequence, an endogenous-type ALV. Both CEF- and vaccine-derived RT activity could be blocked by antibodies to ALV RT. Release of ALV-like virus particles from uninoculated CEF was also documented by electron microscopy. Nonetheless, infectivity studies on susceptible 15B1 chicken cells gave no evidence of infectious ALV, which is consistent with the phenotypes of the ev loci identified in the CEF. PCR analysis of ALV and EAV proviral sequences in peripheral blood mononuclear cells from 33 children after measles and mumps vaccination yielded negative results. Our data indicate that the sources of RT activity in all RT-positive measles and mumps vaccines may not be similar and depend on the particular endogenous retroviral loci present in the chicken cell substrate used. The present data do not support transmission of either ALV or EAV to recipients of the U.S.-made vaccine and provide reassurance for current immunization policies.

No evidence of infection with porcine endogenous retrovirus in recipients of porcine islet-cell xenografts.

BACKGROUND: The study of whether porcine xenografts can lead to porcine endogenous retrovirus (PERV) infection of recipients is critical for evaluating the safety of pig-to-man xenotransplantation. PERV is carried in the pig germline, and all recipients of porcine tissues or organs will be exposed to the virus. METHODS: We studied 10 diabetic patients who had received porcine fetal islets between 1990 and 1993, looking for evidence of PERV infection by using PCR serology, PCR, and reverse transcriptase assays. Prolonged xenograft survival (up to a year) was confirmed in five patients by porcine C-peptide excretion and detection of pig mitochondrial DNA (mtDNA) in serum. FINDINGS: Despite the evidence for extended exposure to pig cells and despite concomitant immunosuppressive therapy, we were unable to detect markers of PERV infection in any patient. Screening for two PERV sequences in peripheral blood lymphocytes collected 4-7 years after the xenotransplantation was negative. Markers of PERV expression, including viral RNA and reverse transcriptase, were undetectable in sera from both early (day 3 to day 180) and late (4-7 years) time points. Western blot analysis for antibodies was consistently negative. INTERPRETATION: These results suggested the absence of PERV infection in these patients. Also this study establishes a minimum standard for post-transplant surveillance of patients given porcine xenografts.

Amplification of simian retroviral sequences from human recipients of baboon liver transplants.

Investigations into the use of baboons as organ donors for human transplant recipients, a procedure called xenotransplantation, have raised the specter of transmitting baboon viruses to humans and possibly establishing new human infectious diseases. Retrospective analysis of tissues from two human transplant recipients with end-stage hepatic disease who died 70 and 27 days after the transplantation of baboon livers revealed the presence of two simian retroviruses of baboon origin, simian foamy virus (SFV) and baboon endogenous virus (BaEV), in multiple tissue compartments. The presence of baboon mitochondrial DNA was also detected in these same tissues, suggesting that xenogeneic "passenger leukocytes" harboring latent or active viral infections had migrated from the xenografts to distant sites within the human recipients. The persistence of SFV and BaEV in human recipients throughout the posttransplant period underscores the potential infectious risks associated with xenotransplantation.

Identification of a human population infected with simian foamy viruses.

Studying the transmission of simian retroviruses to humans can help define the importance of these infections to public health. We identified a substantial prevalence (4/231, 1.8%) of infection with simian foamy viruses (SFV) among humans occupationally exposed to nonhuman primates. Evidence of SFV infection included seropositivity, proviral DNA detection and isolation of foamy virus. The infecting SFV originated from an African green monkey (one person) and baboons (three people). These infections have not as yet resulted in either disease or sexual transmission, and may represent benign endpoint infections.

Sensitivity and specificity of a DNA polymerase chain reaction nonisotopic-based detection method for the confirmation of infection with human T-lymphotropic virus types I and II.

BACKGROUND: A convenient, standard format for the detection of polymerase chain reaction (PCR) amplicons would increase the use of PCR for the confirmation of infection with human T-lymphotropic virus types I and II (HTLV-I and HTLV-II). OBJECTIVES: To determine the sensitivity and specificity of an enzyme oligonucleotide assay (EOA) for the confirmation of infection with HTLV-I or HTLV-II. STUDY DESIGN: The sensitivity of the EOA was determined by examining 88 specimens representing diverse geographic-associated genotypes and clinical manifestations. The specificity was determined by testing 40 HTLV-seroindeterminate (PCR-negative) specimens. RESULTS: Of the 52 HTLV-I-positive specimens tested, 46 (88%) were confirmed positive for HTLV-I by the EOA; these included 25 of 30 (83%) specimens from asymptomatic carriers, 14 of 15 (93%) specimens from patients with HTLV-I-associated myelopathy, and all 7 specimens from patients with adult T-cell leukemia. Similarly, 33 of 36 (92%) HTLV-II-positive specimens were confirmed positive for HTLV-II. None of the specimens were wrongly classified. All specimens tested with distinct geographic-associated genotypes for HTLV-I and -II were detected by EOA. Analysis of seroindeterminate specimens, all of which were previously shown to be negative by nested PCR, showed that none of 40 were detected by either the HTLV-I or HTLV-II EOA. CONCLUSIONS: The overall sensitivity of the EOA detection for confirmation of HTLV-I and HTLV-II was 79 of 88 (90%) and the overall specificity was 100%. These findings demonstrate that the EOA provides a simple, standardized assay system for reliable confirmation and typing of HTLV infection.

Male-to-female transmission of human T-cell lymphotropic virus types I and II: association with viral load. The Retrovirus Epidemiology Donor Study Group.

SUMMARY: Risk factors for male-to-female sexual transmission of human T-lymphotropic virus types I and II (HTLV-I/II) were investigated among HTLV-seropositive volunteer blood donors and their long-term (> or = 6 month) sex partners. Direction of transmission in concordantly seropositive pairs was assessed by analyzing risk factors for HTLV infection. Donors and their partners were also questioned regarding sexual behaviors during their relationships; HTLV antibody titers and viral load were determined for specimens from male partners. Among 31 couples in whom HTLV-infected men likely transmitted infection to their partners (11 HTLV-I and 20 HTLV-II) and 25 male-positive, female-negative couples (8 HTLV-I and 17 HTLV-II), HTLV transmitter men had been in their relationships longer (mean 225 months vs. 122 months) and had higher viral loads (geometric mean 257,549 vs. 2,945 copies/300,000 cells for HTLV-I; 5,541 vs. 118 copies/300,000 cells for HTLV-II) than non-transmitters (P = 0.018 and P = 0.001 for duration of relationship and viral load, respectively, logistic regression analysis). Transmitter men also tended to have higher antibody titers against various env and whole virus proteins than non-transmitters. The identification of high viral load and duration of relationship as risk factors provides a biologically plausible framework in which to assess risk of sexual transmission of the HTLVs.

Endemicity and phylogeny of the human T cell lymphotropic virus type II subtype A from the Kayapo Indians of Brazil: evidence for limited regional dissemination.

Long terminal repeat (LTR)-based restriction fragment length polymorphism (RFLP) analysis of human T cell lymphotropic virus type II (HTLV-II) from 17 seropositive Kayapo Indians from Brazil showed that all 17 samples contained a unique HTLV-IIa subtype (A-II). Additional RFLP screening demonstrated the presence of this subtype in two of three Brazilian blood donors and a Mexican prostitute and her child. In contrast, 129 samples from blood donors and intravenous drug users (IDUs) from the United States, two Pueblo Indian samples, five samples from Norwegian IDUs, and two samples from blood donors from Denmark were all found to be a different HTLV-IIa subtype (A-III). Phylogenetic analysis of two Kayapo and one Mexican LTR sequences showed that they cluster with a subtype A-II sequence from a Brazilian blood donor and with sequences from two prostitutes from Ghana and Cameroon. These results demonstrate that infection with the A-II subtype is endemic among the Kayapo Amerindians, has disseminated to non-Indian populations in Brazil, and is also present in Mexico. Furthermore, the A-II subtype does not appear to represent an origin for the HTLV-IIa infection in urban areas of the United States and Europe. This study provides evidence that HTLV-IIa may be a Paleo-Indian subtype as previously suggested for HTLV-IIb.

Mother-to-child transmission of human T-lymphotropic virus type II.

OBJECTIVE: To determine the frequency of mother-to-child transmission of human T-lymphotropic virus type II (HTLV-II) and to explore its association with breast-feeding. DESIGN: Prospective study of children born to a cohort of HTLV-II-infected pregnant women and a cross-sectional study of older siblings of these children. METHODS: Maternal sera were screened with an HTLV-I enzyme immunoassay that detects antibody to both HTLV-I and HTLV-II. Confirmatory serologic testing and viral typing were performed by Western blot, radioimmunoprecipitation assay, enzyme immunoassay with HTLV type-specific proteins, and polymerase chain reaction (PCR) analysis of DNA from peripheral blood mononuclear cells. The presence of HTLV was evaluated in children by serial serologic and PCR testing. Molecular analysis of PCR products from infected mother-child pairs was performed by means of restriction fragment length polymorphism of HTLV-II long-terminal repeated sequences. RESULTS: Twenty-nine HTLV-II-infected women were identified, and these 29 women had 30 pregnancies during the study. Of 28 live infants born to infected women, 19 were examined and none was infected with HTLV-II. Sixteen older children less than 10 years of age who were born previously to the infected women were also examined; two were infected with HTLV-II. One infected child was breast fed for 2 months and the second was not breast fed. The viral patterns of restriction fragment length polymorphism in the two infected children were distinct, but the viral pattern in each child was identical to that of her mother's virus, suggesting mother-to-child transmission. Overall, among examined children, 1 of 7 breast-fed children (14%; 95% confidence interval: 0, 40) and 1 of 28 children who were not breast fed (3.6%; 95% confidence interval: 0, 10) were infected with HTLV-II. CONCLUSION: Mother-to-child transmission of HTLV-II occurs both with and without breast-feeding and at rates similar to those of HTLV-I. We believe that this is the first demonstration of mother-to-child transmission of HTLV-II in the absence of breast-feeding.