Sexual transmission of human T-cell lymphotropic virus type 1

Human T-cell lymphotropic virus type 1 (HTLV-1) is endemic in many parts of the world and is primarily transmitted through sexual intercourse or from mother to child. Sexual transmission occurs more efficiently from men to women than women to men and might be enhanced by sexually transmitted diseases that cause ulcers and result in mucosal ruptures, such as syphilis, herpes simplex type 2 (HSV-2), and chancroid. Other sexually transmitted diseases might result in the recruitment of inflammatory cells and could increase the risk of HTLV-1 acquisition and transmission. Additionally, factors that are associated with higher transmission risks include the presence of antibodies against the viral oncoprotein Tax (anti-Tax), a higher proviral load in peripheral blood lymphocytes, and increased cervicovaginal or seminal secretions. Seminal fluid has been reported to increase HTLV replication and transmission, whereas male circumcision and neutralizing antibodies might have a protective effect. Recently, free virions were discovered in plasma, which reveals a possible new mode of HTLV replication. It is unclear how this discovery might affect the routes of HTLV transmission, particularly sexual transmission, because HTLV transmission rates are significantly higher from men to women than women to men.

Patterns of serologic response to human immunodeficiency virus type 1 (HIV-1) in brazilians with different clinical forms of HIV infection

In order to investigate the IgG HIV-1 antibodies rectivity to structural components of the virus, 85 sera from infected Brazilians, comprising the total spectrum of HIV infection, were analysed by Western blot assay. The sera were confirmed as being positive to HIV with enzyme linked immuno assay (ELISA) and indirect immunofluorescence (IIF). Although the sera from patients reacted less intensively to the gag polypeptide of 55KDa, no distinctive antigen reaction patterns were observed between sera patients with different clinical forms. Because of the higher frequency of reactivity to the gag p24 in AIDS patients, the patterns of anti-HIV IgG responses are similar to those observed in their African counterparts.

Brazilian dengue virus type 1 replication in mosquito cell cultures

The development of dengue viruses type 1 obtained from accute human sera and inoculated into mosquito cell cultures, was observed by standard transmission electron microscopy and cytochemical staining. It follows the trans-type mechanism already estabilished of other dengue types. Directed passage of single virus particles across the cell membrane seems to be a pathway of entry and exit in dengue-1 infected cells. The nature of numerous electron translucent vesicles and tubules, produced simmultaneously during virus replication inside the rough endoplasmic reticulum, was analyzed by cytochemical tests. The largest amount of virus particles was produced inside cell syncytia.

Rapid in vitro detection of HIV-1-specific antibody secretion by cells-culture with virus antigens

The present report describes an alternative method for in vitro detection of HIV-1 -specific antibody secretion in 24h of culture employing as stimulant of peripheral blood mononuclear cells the disrupted inactivated whole virus adsorbed onto microwells in a commercial ELISA kit plates. The results obtained from this technique have showed high sensitivity and specificity since it was capable of detecting HIV-1 infection early after birth. There were neither false-positivity nor false-negativity when blood samples obtained from HIV-1 seronegative asymptomatic individuals, and HIV-1 seropositive adult patients were analized. This rapid, low cost, simple, highly sensitive and specific assay can be extremely useful for early diagnosis of pediatric HIV infection.

Dried blood spots collected on filter paper: an international resource for the diagnosis and genetic characterization of human immunodeficiency virus Type-1

The collection of dried blood spots (DBS) on filter paper provides a powerful approach for the development of large-scale, population-based screening programs. DBS methods are particularly valuable in developing countries and isolated rural regions where resources are limited. Large numbers of field specimens can be economically collected and shipped to centralized reference laboratories for genetic and (or) serological analysis. Alternatively, the dried blood can be stored and used as an archival resource to rapidly establish the frequency and distribution of newly recognized mutations, confirm patient identity or track the origins and emergence of newly identified pathogens. In this report, we describe how PCR-based technologies are beginning to interface with international screening programmes for the diagnosis and genetic characterization of human immunodeficiency virus type 1 (HIV-1). In particular, we review recent progress using DBS specimens to resolve the HIV-1 infection status of neonates, monitor the genetic evolution of HIV-1 during early infancy and establish a sentinel surveillance system for the systematic monitoring of HIV-1 genetic variation in Asia.

Coinfection by Strongyloides stercoralis in blood donors infected with human T-cell leukemia/lymphoma virus type 1 in São Paulo city, Brazil

The frequency of coinfection with Strongyloides stercoralis and human T-cell leukemia/lymphoma virus type 1 (HTML-1) was determined in 91 blood donors examined at the blood bank of a large hospital in São Paulo city, Brazil. As control group 61 individuals, not infected by HTLV-1, were submitted to the same techniques for the diagnosis of S. stercoralis infection. In HTLV-1 infected patients the frequency of S. stercoralis infection was 12.1%; on the other hand, the control group showed a frequency significantly lower of S. stercoralis infection (1.6%), suggesting that HTLV-1 patients shoud be considered as a high risk group for strongyloidiasis in São Paulo city.

Vertical human immunodeficiency virus type 1 - HIV-1 -transmission - a review

Several factors appear to affect vertical HIV-1 transmission, dependent mainly on characteristics of the mother (extent of immunodeficiency, co-infections, risk behaviour, nutritional status, immune response, genetical make-up), but also of the virus (phenotype, tropism) and, possibly, of the child (genetical make-up). This complex situation is compounded by the fact that the virus may have the whole gestation period, apart from variable periods between membrane rupture and birth and the breast-feeding period, to pass from the mother to the infant. It seems probable that an extensive interplay of all factors occurs, and that some factors may be more important during specific periods and other factors in other periods. Factors predominant in protection against in utero transmission may be less important for peri-natal transmission, and probably quite different from those that predominantly affect transmission by mothers milk. For instance, cytotoxic T lymphocytes will probably be unable to exert any effect during breast-feeding, while neutralizing antibodies will be unable to protect transmission by HIV transmitted through infected cells. Furthermore, some responses may be capable of controlling transmission of determined virus types, while being inadequate for controlling others. As occurence of mixed infections and recombination of HIV-1 types is a known fact, it does not appear possible to prevent vertical HIV-1 transmission by reinforcing just one of the factors, and probably a general strategy including all known factors must be used. Recent reports have brought information on vertical HIV-1 transmission in a variety of research fields, which will have to be considered in conjunction as background for specific studies.

Polymorphism of the Human Immunodeficiency Virus Type 1 in Brazil: Genetic Characterization of the nef Gene and Implications for Vaccine Design

Most of the Brazilian HIV-1 samples have been characterized based on the structural genes (env, gag and pol) and no data concerning the variability of the accessory genes such as nef have been available so far. Considering the role of the nef on virus biology and the inclusion of this region in some HIV/AIDS vaccine products under testing, the purpose of this study was to document the genetic diversity of the nef gene in third-four HIV-1 Brazilian samples previously subtyped based on the env C2-V3 region. Although only few non-subtype B samples have already been analyzed so far, the cytotoxic Tlymphocyte epitopes encoded in this region were relatively conserved among the subtypes, with some amino acid signatures mainly in the subtype C samples. Considering the increasing of the non-B HIV-1 subtypes worldwide, in special the subtype C, more data should be generated concerning the genetic and antigenic variability of these subtypes, as well as the study of the impact of such polymorphism in HIV/AIDS vaccine design and testing.

Sequence and phylogenetic analysis of human T cell lymphotropic virus type 1 from Tumaco, Colombia

Human T cell lymphotropic virus type 1 (HTLV-1) is a retrovirus that causes leukemia and the neurological disorder HTLV-1 associated myelopathy or tropical spastic paraparesis (HAM/TSP). Infection with this virus - although it is distributed worldwide - is limited to certain endemic areas of the world. Despite its specific distribution and slow mutation rate, molecular epidemiology on this virus has been useful to follow the movements of human populations and routes of virus spread to different continents. In the present study, we analyzed the genetic variability of a region of the env gene of isolates obtained from individuals of African origin that live on the Pacific coast of Colombia. Sequencing and comparison of the fragment with the same fragment from different HTLV-1 isolates showed a variability ranging from 0.8% to 1.2%. Phylogenetic studies permit us to include these isolates in the transcontinental subgroup A in which samples isolated from Brazil and Chile are also found. Further analyses will be necessary to determine if these isolates were recently introduced into the American continent or if they rather correspond to isolates introduced during the Paleolithic period.

Human immunodeficiency virus type 1: drug resistance in treated and untreated Brazilian children

Twenty-two vertically human immunodeficiency virus type 1 (HIV-1) infected Brazilian children were studied for antiretroviral drug resistance. They were separated into 2 groups according to the administration of antiretroviral therapy into those who presented disease symptoms or without symptoms and no therapy. Viral genome sequencing reactions were loaded on an automated DNA sampler (TruGene, Visible Genetics) and compared to a database of wild type HIV-1. In the former group 8 of 12 children presented isolates with mutations conferring resistance to protease inhibitors (PIs), 7 presented isolates resistant to nucleoside reverse transcriptase inhibitors (NRTIs) and 2 presented isolates resistant to non-nucleoside reverse transcriptase inhibitors (NNRTIs). Ten children were included in the antiretroviral naïve group. Eight were susceptible to NRTIs and all of them were susceptible to PIs; one presented the V108I mutation, which confers low-level resistance to NNRTIs. The data report HIV mutant isolates both in treated and untreated infants. However, the frequency and the level of drug resistance were more frequent in the group receiving antiretroviral therapy, corroborating the concept of selective pressure acting on the emergence of resistant viral strains. The children who presented alterations at polymorphism sites should be monitored for the development of additional mutations occurring at relevant resistance codons.

Human immunodeficiency virus type 1 Brazilian subtype B variant showed an increasing avidity of the anti-V3 antibodies over time compared to the subtype B US/European strain in São Paulo, Brazil

The Brazilian variant of human immunodeficiency virus type 1 (HIV-1) subtype B, (serotype B"-GWGR), has a tryptophan replacing the proline in position 328 the HIV-1 envelope. A longer median time period from infection to acquired immunodeficiency syndrome (AIDS) for serotype B (B"-GWGR) infected subjects compared to the B-GPGR US/European strain was reported. In a cohort study, in São Paulo city, 10 B"-GWGR patients had a statistically significant increased avidity of the anti-V3 antibodies, from 79% ± 33% to 85% ± 75%, versus from 48% ± 59% to 32% ± 17% for the 10 B-GPGR subjects (p = 0.02). The T CD4+ cells showed a mean increase of + 0.45 cells/month for the B-GPGR subjects and for B"-GWGR the slope was + 1.24 cells/month (p = 0.06), for 62 and 55 months of follow up, respectively. RNA plasma viral load decreased from 3.98 ± 1.75 to 2.16 ± 1.54 log10 in the B"-GWGR group while B-GPGR patients showed one log10 reduction in viral load from 4.09 ± 0.38 to 3.17 ± 1.47 log10 over time (p = 0.23), with a decreasing slope of 0.0042 ± log10,/month and 0.0080 ± log10/month, for B-GPGR and B"-GWGR patients, respectively (p = 0.53). Neither group presented any AIDS defining events during the study, according to Center for Diseases Control criteria. Although the sample size is small, these results may indicate that differences in the pathogenicity of the 2 HIV-1 B serotypes which co-circulate in Brazil may be correlated to the avidity of anti-V3 antibodies.

Antiretroviral resistance and genetic diversity of human immunodeficiency virus type 1 isolates from the Federal District, Central Brazil

In the context of universal access to antiretroviral therapy, the surveillance of human immunodeficiency virus type 1 (HIV-1) genetic diversity and resistance becomes pivotal. In this work our purpose was to describe the genetic variability; prevalence of drug-resistance mutations; and genotypic resistance profiles in HIV-1 infected individuals under antiretroviral treatment, from the Federal District, Brasília, Central Brazil. The entire viral protease and codons 19 to 234 of the reverse transcriptase gene from 45 HIV-1 isolates were amplified and sequenced for subtyping and genotyping. By phylogenetic analysis, 96% of the samples clustered with subtype B and the remaining 4% with HIV-1 subtype F sequences. One major protease inhibitor resistance-associated mutation, I50V, was detected in 38% of the samples. Minor mutations were also found at the protease gene: L10I/V (7%), K20M (2%), M36I (11%), L63P (20%), A71T (2%), and V77I (7%). Many mutations associated with reduced susceptibility to nucleoside or non-nucleoside reverse transcriptase inhibitors were detected: M41L (11%), E44D (4%), D67N (11%), T69D (2%), K70R (11%), L74V (2%), L100I (4%), K103N (18%), V118I (9%), Y181C (11%), M184V (18%), G190A (4%), T215Y (4%), and K219E (4%). This study has shown that 84% of the studied population from the Federal District, showing evidences of therapy failure, presented viral genomic mutations associated with drug resistance. The main antiretrovirals to which this population showed resistance were the PI amprenavir (38%), the NNRTIs delavirdine, nevirapine (31%), and efavirenz (24%), and the NRTIs lamivudine (18%), abacavir, and zidovudine (13%).

Human immunodeficiency virus type 1 (HIV-1) genotyping in Rio de Janeiro, Brazil: assessing subtype and drug-resistance associated mutations in HIV-1 infected individuals failing highly active antiretroviral therapy

In order to assess the human immunodeficiency virus type 1 (HIV-1) drug resistance mutation profiles and evaluate the distribution of the genetic subtypes in the state of Rio de Janeiro, Brazil, blood samples from 547 HIV-1 infected patients failing antiretroviral (ARV) therapy, were collected during the years 2002 and 2003 to perform the viral resistance genotyping at the Renageno Laboratory from Rio de Janeiro (Oswaldo Cruz Foundation). Viral resistance genotyping was performed using ViroSeqTM Genotyping System (Celera Diagnostic-Abbott, US). The HIV-1 subtyping based on polymerase (pol) gene sequences (protease and reverse transcriptase-RT regions) was as follows: subtype B (91.2%), subtype F (4.9%), and B/F viral recombinant forms (3.3%). The subtype C was identified in two patients (0.4%) and the recombinant CRF_02/AG virus was found infecting one patient (0.2%). The HIV-1 genotyping profile associated to the reverse transcriptase inhibitors has shown a high frequency of the M184V mutation followed by the timidine-associated mutations. The K103N mutation was the most prevalent to the non-nucleoside RT inhibitor and the resistance associated to protease inhibitor showed the minor mutations L63P, L10F/R, and A71V as the more prevalent. A large proportion of subtype B was observed in HIV-1 treated patients from Rio de Janeiro. In addition, we have identified the circulation of drug-resistant HIV-1 subtype C and are presenting the first report of the occurrence of an African recombinant CRF_02/AG virus in Rio de Janeiro, Brazil. A clear association between HIV-1 subtypes and protease resistance mutations was observed in this study. The maintenance of resistance genotyping programs for HIV-1 failing patients is important to the management of ARV therapies and to attempt and monitor the HIV-1 subtype prevalence in Brazil.

Human immunodeficiency virus type 1 neutralization by plasma from B or F genotype infected individuals

Anti-human immunodeficiency virus type 1 (HIV-1) "binding antibodies" (antibodies capable of binding to synthetic peptides or proteins) occur throughout HIV-1 infection, are high-titered and highly cross-reactive, as confirmed in this study by analyzing plasma from B and F genotype HIV-1 infected individuals. Plasma from individuals infected with clade F HIV-1 displayed the most frequent cross-reactivity, in high titers, while Bbr plasma showed much higher specificity. Similarly, neutralization of a reference HIV-1 isolate (HIV-1 MN) was more frequently observed by plasma from F than B genotype infected individuals. No significant difference was seen in neutralization susceptibility of primary B, Bbr or F clade HIV-1 by plasma from individuals infected with the classical B (GPGR) or F HIV-1, but Bbr (GWGR) plasma were less likely to neutralize the F genotype primary HIV-1 isolates. The data indicate that both B and F genotype derived vaccines would be equally effective against B and F HIV-1 infection, with a slightly more probable effectiveness for F than B genotype. Although the Bbr variant appears to induce a much more specific humoral immune response, the susceptibility in neutralizing the Brazilian HIV-1 B genotype Bbr variant is similar to that observed with the classical B genotype HIV-1.