Induction of CD137 expression by viral genes reduces T cell costimulation.

Intracellular pathogens are subject to elimination by a cellular immune response, and were therefore under evolutionary pressure to develop mechanisms that allow them to inhibit especially this arm of immunity. CD137, a T cell costimulatory molecule, and its ligand, CD137 ligand (CD137L), which is expressed on antigen presenting cells (APC), are potent drivers of cellular cytotoxic immune responses. Here, we report that different viruses usurp a negative feedback mechanism for the CD137-CD137L system that weakens cellular immune responses. Latent membrane protein (LMP)-1 and Tax, oncogenes of Epstein-Barr virus (EBV), and human T-cell lymphotropic virus (HTLV)-1, respectively, induce the expression of CD137. CD137 is transferred by trogocytosis to CD137L-expressing APC, and the CD137-CD137L complex is internalized and degraded, resulting in a reduced CD137-mediated T cell costimulation and a weakened cellular immune response which may facilitate the escape of the virus from immune surveillance. These data identify the usurpation of a CD137-based negative feedback mechanism by intracellular pathogens that enables them to reduce T cell costimulation.

Seroprevalence of HIV, HTLV, CMV, HBV and rubella virus infections in pregnant adolescents who received care in the city of Belém, Pará, Northern Brazil.

BACKGROUND: Prenatal tests are important for prevention of vertical transmission of various infectious agents. The objective of this study was to describe the prevalence of human immunodeficiency virus (HIV), human T-lymphotropic virus (HTLV), hepatitis B virus (HBV), cytomegalovirus (CMV), rubella virus and vaccination coverage against HBV in pregnant adolescents who received care in the city of Belém, Pará, Brazil. METHODS: A cross-sectional study was performed with 324 pregnant adolescents from 2009 to 2010. After the interview and blood collection, the patients were screened for antibodies and/or antigens against HIV-1/2, HTLV-1/2, CMV, rubella virus and HBV. The epidemiological variables were demonstrated using descriptive statistics with the G, χ2 and Fisher exact tests. RESULTS: The mean age of the participants was 15.8 years, and the majority (65.4%) had less than 6 years of education. The mean age at first intercourse was 14.4 years, and 60.8% reported having a partner aged between 12 and 14 years. The prevalence of HIV infection was 0.3%, and of HTLV infection was 0.6%. Regarding HBV, 0.6% of the participants had acute infection, 9.9% had a previous infection, 16.7% had vaccine immunity and 72.8% were susceptible to infection. The presence of anti-HBs was greater in adolescent between 12 and 14 years old (28.8%) while the anti-HBc was greater in adolescent between 15 and 18 years old (10.3%). Most of the adolescents presented the IgG antibody to CMV (96.3%) and rubella (92.3%). None of the participants had acute rubella infection, and 2.2% had anti-CMV IgM. CONCLUSIONS: This study is the first report of the seroepidemiology of infectious agents in a population of pregnant adolescents in the Northern region of Brazil. Most of the adolescents had low levels of education, were susceptible to HBV infection and had IgG antibodies to CMV and rubella virus. The prevalence of HBV, HIV and HTLV was similar to that reported in other regions of Brazil. However, the presence of these agents in this younger population reinforces the need for good prenatal follow-up and more comprehensive vaccination campaigns against HBV due to the large number of women susceptible to the virus.

Vaccination against δ-retroviruses: the bovine leukemia virus paradigm.

Bovine leukemia virus (BLV) and human T-lymphotropic virus type 1 (HTLV-1) are closely related d-retroviruses that induce hematological diseases. HTLV-1 infects about 15 million people worldwide, mainly in subtropical areas. HTLV-1 induces a wide spectrum of diseases (e.g., HTLV-associated myelopathy/tropical spastic paraparesis) and leukemia/lymphoma (adult T-cell leukemia). Bovine leukemia virus is a major pathogen of cattle, causing important economic losses due to a reduction in production, export limitations and lymphoma-associated death. In the absence of satisfactory treatment for these diseases and besides the prevention of transmission, the best option to reduce the prevalence of d-retroviruses is vaccination. Here, we provide an overview of the different vaccination strategies in the BLV model and outline key parameters required for vaccine efficacy.

New strain of human T lymphotropic virus (HTLV) type 3 in a Pygmy from Cameroon with peculiar HTLV serologic results.

A search for human T lymphotropic virus (HTLV) types 1 and 2 and related viruses was performed by serological and molecular means on samples obtained from 421 adult villagers from the southern Cameroon forest areas. One individual (a 56-year-old Baka Pygmy hunter) was found to be HTLV-3 infected; however, there was a low proviral load in blood cells. Complete sequence analysis of this virus (HTLV-3Lobak18) indicated a close relationship to human HTLV-3Pyl43 and simian STLV-3CTO604 strains. Plasma samples from Lobak18, the HTLV-3 infected individual, exhibited a peculiar "HTLV-2-like" pattern on Western blot analysis and were serologically untypeable by line immunoassay. These results were different from those for the 2 previously reported HTLV-3 strains, raising questions about serological confirmation of infection with such retroviruses.

Cell surface expression of the bovine leukemia virus-binding receptor on B and T lymphocytes is induced by receptor engagement.

Bovine leukemia virus (BLV), one of the most common infectious viruses of cattle, is endemic in many herds. Approximately 30-40% of adult cows in the United States are infected by this oncogenic C-type retrovirus and 1-5% of animals will eventually develop a malignant lymphoma. BLV, like the human and simian T cell leukemia viruses, is a deltaretrovirus but, in contrast with the latter, the BLV receptor remains unidentified. In this study, we demonstrate that the amino-terminal 182 residues of the BLV envelope glycoprotein surface unit encompasses the receptor-binding domain. A bona fide interaction of this receptor-binding domain with the BLV receptor was demonstrated by specific interference with BLV, but not human T cell leukemia virus, envelope glycoprotein-mediated binding. We generated a rabbit Ig Fc-tagged BLV receptor-binding domain construct and ascertained that the ligand binds the BLV receptor on target cells from multiple species. Using this tool, we determined that the BLV-binding receptor is expressed on differentiating pro/pre-B cells in mouse bone marrow. However, the receptor was not detected on mature/quiescent B cells but was induced upon B cell activation. Activation of human B and T lymphocytes also induced surface BLV-binding receptor expression and required de novo protein synthesis. Receptor levels were down-regulated as activated lymphocytes returned to quiescence. In the human thymus, BLV-binding receptor expression was specifically detected on thymocytes responding to the IL-7 cytokine. Thus, expression of the BLV-binding receptor is a marker of enhanced metabolic activity in B cells, T cells, and thymocytes.

The risk of HIV, HBV, HCV and HTLV infection among musculoskeletal tissue donors in Australia.

In Australia, there are no current national estimates of the risks of transmission of human immunodeficiency virus (HIV), hepatitis B virus (HBV), hepatitis C virus (HCV) or human T-lymphotrophic virus (HTLV) by musculoskeletal tissue transplantation. We determined the prevalence rates of antibodies against HIV (anti-HIV), HCV (anti-HCV) and HTLV (anti-HTLV) and Hepatitis B surface antigen (HBsAg) for 12,415 musculoskeletal tissue donors from three major bone tissue banks across Australia for the period 1993-2004. The prevalence (per 100,000 persons) was 64.44 for anti-HIV, 407.13 for HBsAg, 534.63 for anti-HCV and 121.88 for anti-HTLV. The estimated probability of viremia at the time of donation was 1 in 128,000, 1 in 189,000, 1 in 55,000 and 1 in 118,000, respectively. With the addition of nucleic acid amplification testing (NAT), the probability of donor viremia would be reduced to 1 in 315,000 for HIV, 1 in 385,000 for HBV and 1 in 500,000 for HCV. The prevalence of HIV, HBV, HCV and HTLV although low, are higher among musculoskeletal tissue donors than among first-time blood donors. The risks associated with musculoskeletal donation will be reduced with NAT, though further cost analysis is required prior to its implementation.

Risk assessment in haematopoietic stem cell transplantation: viral status.

Viral infections have been important complications in the transplant procedure from the early days of stem-cell transplantation, causing significant morbidity and mortality. It is important for the management of patients to assess the risk for viral infections that might develop after the stem-cell transplantation. This can be exemplified by cytomegalovirus (CMV) and other herpesviruses, but risk assessment is also important for other viral infections. The aim of this review is to describe current knowledge regarding recipient and donor serological status for viral infections.

Expression of tumor necrosis factor-alpha in IgM+ B-cells from bovine leukemia virus-infected lymphocytotic sheep.

Tumor necrosis factor (TNF)-alpha is thought to be one of the cytokines that account for bovine leukemia virus (BLV)-induced B-cell lymphoproliferative disorder, however, information on TNF-alpha expression in B-cells is limited. In this study, the expression of TNF-alpha in IgM(+) B-cells from BLV-infected sheep with or without lymphocytosis was determined. Freshly isolated IgM(+) B-cells from three sheep with lymphocytosis constitutively transcribed TNF-alpha mRNA. Although TNF-alpha mRNA expression in IgM(+) B-cells was transiently up-regulated after cell culture, TNF-alpha mRNA expression was markedly higher in lymphocytotic sheep when compared to that of non-lymphocytotic sheep or uninfected sheep. Expression of membrane-bound TNF-alpha on IgM(+) B-cells was also augmented in lymphocytotic sheep. TNF-alpha expression in lymphocytotic sheep may support the proliferation of B-cells.

Establishing the reactivity of monoclonal antibodies against porcine endogenous retrovirus envelope protein.

Xenotransplantation of pig organs may be associated with a risk of transmission of microorganisms. Porcine endogenous retroviruses (PERV) are of particular concern since in vitro experiments have demonstrated that human cells are susceptible to such microorganisms. To monitor the transmission of PERV, highly sensitive and specific immunoassays must be developed for clinical surveillance. This report describes the production, preliminary characterization and application of a monoclonal antibody (mAb) against a recombinant PERV envelope (Env) protein. The generated mAb was tested using recombinant PERV Env protein expressed in Escherichia coli, purified PERV virus particles and human 293 cell line infected with PERV. PERV-translated proteins of 15, 70 and 85 kD were recognized specifically using PERV-8E10 mAb and Western blotting. No cross-reactivity was demonstrated with exogenous viral protein (HIV, HTLV and MuLV). Moreover, PERV-8E10 mAb can be applied to localize PERV proteins using an immunoperoxidase assay. This work reveals that recombinant PERV Env protein and mAb may be effective in detecting antibodies against PERV in xenotransplanted patients, or for butchers who have extensive contact with pigs.

Cutting edge: increased NK cell activity in HIV-1-exposed but uninfected Vietnamese intravascular drug users.

We addressed the role of innate immunity in the protection against HIV-1 infection by studying NK cell function in 37 Vietnamese intravascular drug users (IDUs), who appeared to remain HIV-1 uninfected despite many years of high-risk exposure (exposed uninfected, EU), 10 IDUs who underwent seroconversion and 28 unexposed blood donors. Main results were: NK cell lytic activities against both the NK-susceptible K562 cell line and the NK-resistant Daudi cell line were significantly augmented in EU IDUs compared with either controls or seroconverters before or after seroconversion; NK cells producing the cytokines IFN-gamma and TNF-alpha and the beta chemokines CCL3, CCL4, and CCL5 were also increased in the EU IDUs, either after in vitro activation or without stimulation. The finding of an enhanced NK cell function in EU IDUs, especially compared with IDUs who became HIV-1 infected, supports the hypothesis that NK cells contribute to the protection against HIV-1 infection.

[Adult T-cell lymphoma/leukemia: a very rare disease in Europe]. / Das adulte T-Zell Lymphom/Leukämie--eine in Europa sehr seltene Erkrankung.

HISTORY AND CLINICAL FINDINGS: A 45-year-old man was admitted with generalized itchy papules. He was originally from the Carribean island of Grenada. The disease had started two years before and was diagnosed as lupus erythematosus, polymorphic light eruption and atopic eczema. Physical examination showed skin-colored papules all over the integument, sebostasis and enlarged supraclavicular and inguinal lymph nodes. INVESTIGATIONS: Lymphocyte count was elevated with 58% as well as LDH (322 U/l) and gamma GT (133 U/l). In a blood smear characteristic pleomorphic lymphoid cells (flower cells) could be obtained. Histopathologic evaluation demonstrated a subepidermally located infiltrate of pleomorphic lymphocytes with epidermal involvement. HTLV-I/II serology (ELISA-screening test) was positive. Polymerase chain reaction analysis revealed HTLV-specific sequences. DIAGNOSIS, TREATMENT AND COURSE: Diagnosis of adult T-cell lymphoma/leukemia was obtained. Treatment consisted of interferon alpha 2b and zidovudine which resulted in a rapid response. However, as a result of an increased loss of weight (12 kg) this therapy was stopped. Two weeks later generalized lymphadenopathy and disseminated skin lesions were observed. Chemotherapy (CHOP-scheme) was initiated. The patient deceased with signs of an acute leukemia after a short period. CONCLUSIONS: Adult T-cell lymphoma/leukemia is a rare disease in Europe. However, in patients with skin rashes, and lymphadenopathy, which are originally from HTLV-I endemic areas, adult T-cell lymphoma/leukemia should be considered.

Lack of BLV and PTLV DNA sequences in the majority of patients with large granular lymphocyte leukaemia.

The primate T-cell lymphoma/leukaemia viruses (PTLV) and bovine leukaemia virus (BLV) comprise a unique genus of retroviruses, infection with which induces seroreactivity in the host against conserved epitopes in their p24 gag and gp21 env cognate proteins. Herein, we have confirmed this serocrossreactivity. Patients with large granular lymphocyte (LGL) leukaemia have frequent seroreactivity to the p24 and gp21 env proteins of human T-cell lymphoma/leukaemia virus I (HTLV-I), one of the species in the genus. However, only a small minority of patients are actually infected with prototypic HTLV-I or HTLV-II, another species within the group. In an attempt to determine whether LGL leukaemia might be associated with other members of the PTLV/BLV genus, we examined the peripheral blood mononuclear cell DNA of 22 HTLV p24 and/or gp21 seropositive LGL leukaemia patients via PCR using degenerate and specific primer pair/probe systems capable of detecting all known members of the PTLV/BLV genus. None of the samples was positive. These data indicate that although HTLV-II may be associated with some cases of LGL leukaemia most patients are not infected with a PTLV or BLV virus.

Evidence for the cofactor role of human T-cell lymphotropic virus type 1 in mycosis fungoides and Sézary syndrome.

The aetiology of mycosis fungoides (MF) and Sézary syndrome (SS) is unknown. A pathogenic role for the human T-cell lymphotropic virus type 1 (HTLV-1) has been suggested but remains controversial. We used an animal model to test the possibility that peripheral blood mononuclear cells (PBMC) obtained from MF patients harbour the HTLV-1 virus which may be infective. The polymerase chain reaction (PCR) was used to detect HTLV-1 proviral DNA sequences in PBMC of 27 MF patients and one SS patient of non-Iranian origin. Positive results were found in six of the patients. Twelve of the 28 patients tested by Western blot showed HTLV-1 antibodies. Twenty-eight immunosuppressed inbred Fisher F344 rats were inoculated intravenously with cultures of PBMC obtained from the 28 patients. Eight of these 28 rats showed antibodies to HTLV-1 while the proviral genome was demonstrated in the blood of only two of the rats. PBMC from two MF patients, in spite of showing negative results for the proviral genome by PCR, still induced HTLV-1 antibody formation in the F344 rat model. None of 10 control rats inoculated with normal donor PBMC showed antibodies to HTLV-1, nor the proviral genome. The present study suggests that HTLV-1 plays a cofactor role in MF/SS patients.

Bloodborne viruses in forensic medical practice in South Africa.

Health care workers are at risk of exposure to bloodborne viruses including human immunodeficiency virus types 1 and 2 (HIV-1 and -2), hepatitis B virus (HBV) and hepatitis C virus (HCV). However, limited data is available regarding these risks to forensic medical personnel who are exposed daily to large numbers of severely traumatized bodies in South Africa, a country that has an existing and growing HIV epidemic and a high HBV seroprevalence. Because no specific prescriptions ensuring occupational safety in this regard exist for forensic medical personnel in South Africa, the prevalence of bloodborne viruses within this setting must be determined. Blood was taken randomly from 263 bodies examined at the Medicolegal Laboratory in Pretoria. Serologic tests to detect antibodies to HIV, HCV, and human T-cell lymphotropic virus types I and II (HTLV-I and -II) and to detect the presence of HBV surface antigen (HBsAg) were performed and positive results confirmed using conventional serologic assays. Serologic tests detected at least one of the four bloodborne viruses in 21% of cases. The overall seroprevalence for HIV-1/2 was 11%, rising to 19% in the sexually active reproductive age group (15 - 49 years). The HBsAg prevalence overall was 8%, rising to 9% in sexually active reproductive individuals. There was a low overall HCV seroprevalence of 1% and an even lower HTLV-I/II seroprevalence of 0.01%. Forensic medical personnel in South Africa are therefore at risk of exposure to bloodborne viral pathogens in, on average, 1 of 5 bodies autopsied. This risk is compounded by the high daily workload, traumatized state of many of the bodies, and adverse working conditions. It is imperative that occupational health safety guidelines be created for the forensic medicine discipline and crime scene attendants in South Africa.

HTLV testing in blood transfusion.

To improve the safety of the blood supply, HTLV screening of blood donations became mandatory in different countries. In Japan and in Europe, the majority of HTLV-infected donors are HTLV-1 whereas in the USA more than half of them are HTLV-II-positive. The prevalence of HTLV-infected donors is low in European Countries as is the rate of seroconversion. Consequently, to test donors only once would have a high efficiency. This procedure is already in use in certain countries. Furthermore, if the use of leucodepleted cell concentrates is generalized, the policies of HTLV screening will still be further modified.

Increased replication of T-cell-tropic HIV strains and CXC-chemokine receptor-4 induction in T cells treated with macrophage inflammatory protein (MIP)-1alpha, MIP-1beta and RANTES beta-chemokines.

OBJECTIVE AND DESIGN: To study, in T-lymphoid cells, the effects of macrophage inflammatory protein (MIP)-1alpha, MIP-1beta and RANTES beta-chemokines on the replication of T-cell-tropic HIV-1 strains, since it has been reported that beta-chemokines interfere with the replication of macrophage-tropic HIV-1 strains, but not T-cell-tropic strains. METHODS: Freshly phytohaemagglutinin (PHA)-activated peripheral blood lymphocytes (PBL) and cultured PHA-activated T cells from healthy volunteers, as well as the C8166 T-cell line, were treated overnight with beta-chemokines before infection with T-cell-tropic HIV-1 isolates, or human T-lymphotropic virus type IIIB. HIV replication was followed by detecting the production of infectious particles, p24 antigen, and viral sequences. CXC-chemokine receptor (CXCR)-4 expression was followed by detection and quantification of specific transcripts. RESULTS: Pretreatment of T cells with MIP-1alpha, MIP-1beta and RANTES affected T-cell-tropic strains, increased the replication of HIV-1beta and HIV-1RPdT strains dose-dependently, as well as virus absorption and provirus DNA accumulation. These findings were associated with increased accumulation of CXCR-4 transcripts, and mediated by the protein tyrosine kinase signalling. Moreover, beta-chemokines stimulated PBL proliferation. CONCLUSIONS: Beta-chemokines increase the adsorption and replication of at least some T-cell-tropic HIV-1 strains, and this is related to stimulated expression of the CXCR-4 coreceptor.