Association between human parvovirus B19 and arthropathy in Bel��m, Par��, north Brazil

A total of 220 patients with arthropathy were selected in Bel��m, Par�� between January 1994 and December 2000, and screened for the presence of human parvovirus B19 IgM and IgG antibodies by enzyme-linked immunosorbent assay (ELISA). A subgroup (n = 132) of patients with high levels of antibodies (either IgM+/IgG+ or IgM-/IgG+) were examined for the presence of DNA by polymerase chain reaction/nested PCR. Recent/active infection (detection of IgM and/or IgG-specific antibodies and presence of viral DNA) was identified in 47.7% of the 132 individuals with arthropathy. In our study, women were significantly more affected (59.7%) than men (35.4%) (P = 0.0006). The age group of 11-20 years (84.6%), among female patients, and 21-30 years (42.1%), among male, were those with the highest incidence rates. The analysis of the temporal distribution of B19-associated arthropaties showed a cyclic pattern, with peak incidence rates occuring at 3-5 year intervals. Significant diference (P = 0.01) was observed when comparing both the highest (39.0%) and the lowest (11.0%) seropositivity rates for the years of 1995 and 2000, respectively. The interfalangial joints of hands and feet were mostly affected, with 50.0% and 48.0% of cases among both women and men, respectively. In a smaller proportion, other joints such as those of knee, ankle, pulse and shoulder were affected. As for the duration, symptoms lasted 1 to 5 days in 54.0% of the individuals, whereas in 46.0% of them the disease lasted 6-10 days, if considered the subgroup (n = 63) of patients with recent/active infection by parvovirus B19. In our study, joint clinical manifestations occurred symmetrically. Our results indicate that B19 may be an important agent of arthropathies in our region, and this underscores the need for specific laboratory diagnosis when treating patients suffering from acute arthropathy, mainly pregnant women.

Evidence of active herpesvirus 6 (variant-A) infection in patients with lymphadenopathy in Bel��m, Par��, Brazil

A total of 323 patients with lymphadenopathy were selected in Bel��m, Brazil, between January 1996 and December 2001, and screened for the presence of human herpesvirus-6 (HHV-6) IgM- and- IgG antibodies by enzyme-linked immunosorbent assay (ELISA). When seroprevalence is analyzed by gender, similar rates are found for female (60.6%) and male (55.7%) individuals. Seventy-seven (23.8%) patients were HHV-6-IgM-and- IgG-positive (IgM+ subgroup), with positivity rates of 29.7% and 17.7% (p = 0.0007) for female- and male individuals, respectively. Sera from a subgroup (n = 120) of these subjects, with high HHV-6 antibody levels (either IgM+ or IgG+ reactivities), were subsequently processed for the presence of HHV-6 DNA by polymerase chain reaction (PCR)/nested PCR. Active infections (IgM+ and/or IgG+ high levels specific antibodies plus detection of viral DNA) were diagnosed in 20/77 (20.0%) and 8/43 (18.6%); subgroup of the 120 individuals suspected of having HHV-6 suggestive recent infection. All (n = 28) cases of active infection were found to be associated with HHV-6 variant-A (HHV-6A), as detectable by PCR/nested PCR, using variant-specific primer that amplify regions of 195 base pairs (bp) (HHV-6A) and 423 bp (HHV-6B). Rates of HHV-6 DNA detection between female and male patients were similar (p > 0.05) in the IgM+ and IgG+ groups: 20.4% versus 35.7% and 25.0% versus 13.0%, respectively. HHV-6 DNA was detected across < 5 through 41-50-year age-groups for patients whose serum samples were IgM+, with rates ranging from 7.7% (female subjects aged < 5 years) to 80.0% (male, 11-20 years). Among patients whose serological status was IgG+, HHV-6 DNA was detected in < 5, 6-10, 21-30 and > 50 age-groups at rates that ranged from 15.4% (male, < 5 years of age) to 100.0% (female aged 11-20 years). Swelling cervical lymph nodes were the most common sign, accounting for 9 (32.0%) cases in each gender group. Among patients (n = 28) with active infection by HHV-6A variant, duration of symptoms lasted 1-5 days in 35.7% of subjects, whereas in 64.3% of them the disease lasted 6-20 days. Our data suggest that it is worth seeking for HHV-6 infection whenever a patient (infant or adult) presents with lymphadenopathy as a prominent symptom in the course of an acute febrile illness.

Determination of human cytomegalovirus genetic diversity in different patient populations in Costa Rica

Seroprevalence of HCMV in Costa Rica is greater than 95% in adults; primary infections occur early in life and is the most frequent congenital infection in newborns. The objectives of this study were to determine the genetic variability and genotypes of HCMV gB gene in Costa Rica. Samples were collected from alcoholics, pregnant women, blood donors, AIDS patients, hematology-oncology (HO) children and HCMV isolates from neonates with cytomegalic inclusion disease. A semi-nested PCR system was used to obtain a product of 293-296 bp of the gB gene to be analyzed by Single Stranded Conformational Polymorphism (SSCP) and sequencing to determine the genetic polymorphic pattern and genotypes, respectively. AIDS patients showed the highest polymorphic diversity with 14 different patterns while fifty-six percent of HO children samples showed the same polymorphic pattern, suggesting in this group a possible nosocomial infection. In neonates three genotypes (gB1, gB2 and gB3), were determined while AIDS patients and blood donors only showed one (gB2). Of all samples analyzed only genotypes gB1, 2 and 3 were determined, genotype gB2 was the most frequent (73%) and mixed infections were not detected. The results of the study indicate that SSCP could be an important tool to detect HCMV intra-hospital infections and suggests a need to include additional study populations to better determine the genotype diversity and prevalence.

Human herpesvirus-7 as a cause of exanthematous ilnesses in Bel��m, Par��, Brazil

We screened sera from 370 patients suffering from exanthematous illnesses in Bel��m, North Brazil, for the presence of human herpesvirus-7 (HHV-7) IgM and IgG antibodies. Samples were obtained from January 1996 to December 2002 and were processed by a HHV-7-specific indirect immunofluorescence assay (IFA). HHV-7-specific IgM and/or IgG antibodies were found in 190 (51.4%) of these patients, with similar prevalence rates (IgM+ and IgG+ subgroups taken together) for female and male subjects: 52.5% and 50.3%, respectively. Serological status as defined by IgG was identified in 135 (36.5%) patients. In 55 (14.9%) of the patients HHV-7 IgM antibodies were detected. HHV-7 IgM- and- IgG antibody rates were similar (p > 0.05) when male and female subjects are compared: 14.4% versus 15.3% and 38.1% versus 35.0%, respectively. Statistically significant difference (p = 0.003) was noted when HHV-7-IgM-positive female and male patients aged 5-8 months are compared. Prevalence rates ranging from 4.6% (female, 5-8 months of age) to 93.3% (female, > 10 years of age) and 12.2% (male, 5-8 months) to 80.0% (male, 8-10 years of age) were noted in the IgG- positive subgroups. A subgroup (n = 131) of patients with IgM or IgG HHV-7 antibodies were examined for the presence of DNA using a polymerase chain reaction/nested PCR. Recent/active HHV-7 infection occurred at a rate of 11.0% (6/55) among patients whose samples presented IgM+ specific antibodies. In a subgroup (n = 76) of patients with high HHV-7-IgG antibody levels (titre > 1:160) DNA could not be detected in sera examined by PCR/nested PCR. Of the six recent/active infections, four subjects with less than 1 year and two with 3 and 6 years of age, presented typical exanthem subitum (E.S), as defined by higher fever (> 38.0 &ordm;C) with duration of 24 to 72 hours, followed by a maculopapular skin rash. Our results underscore the need for searching HHV-7 infection in patients with exanthematous diseases, particularly those presenting with typical E.S. HHV-7 appears therefore to emerge as a newly recognized pathogen of exanthem in our region.

Analysis of HIV- type 1 protease and reverse transcriptase in Brazilian children failing highly active antiretroviral therapy (HAART)

The aim of this study was to evaluate the genotypic resistance profiles of HIV-1 in children failing highly active antiretroviral therapy (HAART). Forty-one children (median age = 67 months) receiving HAART were submitted to genotypic testing when virological failure was detected. cDNA was extracted from PBMCs and amplified by nested PCR for the reverse transcriptase and protease regions of the pol gene. Drug resistance genotypes were determined from DNA sequencing. According to the genotypic analysis, 12/36 (33.3%) and 6/36 (16.6%) children showed resistance and possible resistance, respectively, to ZDV; 5/36 (14%) and 4/36 (11.1%), respectively, showed resistance and possible resistance to ddI; 4/36 (11.1%) showed resistance to 3TC and D4T; and 3/36 (8.3%) showed resistance to Abacavir. A high percentage (54%) of children exhibited mutations conferring resistance to NNRTI class drugs. Respective rates of resistance and possible resistance to PIs were: RTV (12.2%, 7.3%); APV (2.4%, 12.1%); SQV(0%, 12.1%); IDV (14.6%, 4.9%), NFV (22%, 4.9%), LPV/RTV (2.4%, 12.1%). Overall, 37/41 (90%) children exhibited virus with mutations related to drug resistance, while 9% exhibited resistance to all three antiretroviral drug classes.

Comparison of serology, antigenemia assay and the polymerase chain reaction for monitoring active cytomegalovirus infections in hematopoietic stem cell transplantation patients

Forty-six allogeneic hematopoietic stem cell transplantation (HSCT) patients were monitored for the presence of CMV antibodies, CMV-DNA and CMV antigens after transplantation. Immunoenzymatic serological tests were used to detect IgM and the increase in CMV IgG antibodies (increase IgG), a nested polymerase chain reaction (N-PCR) was used to detect CMV-DNA, and an antigenemia assay (AGM) was used to detect CMV antigens. The presence of CMV-IgM and/or CMV-increase IgG antibodies was detected in 12/46 (26.1%) patients, with a median time between HSCT and the detection of positive serology of 81.5 days. A positive AGM was detected in 24/46 (52.2%) patients, with a median time between HSCT and antigen detection of 62 days. Two or more consecutive positive N-PCR results were detected in 32/46 (69.5%) patients, with a median time between HSCT and the first positive PCR of 50.5 days. These results confirmed that AGM and mainly PCR are superior to serology for the early diagnosis of CMV infection. Six patients had CMV-IgM and/or CMV-increase IgG with a negative AGM (five cases) or N-PCR assay (one case). In five of these cases the serological markers were detected during the first 100 days after HSCT, the period of highest risk. These findings support the idea that serology may be useful for monitoring CMV infections in HSCT patients, especially when PCR is unavailable.

Molecular screening of Plasmodium sp. asymptomatic carriers among transfusion centers from Brazilian Amazon region

The transmission of malaria in Brazil is heterogeneous throughout endemic areas and the presence of asymptomatic Plasmodium sp. carriers (APCs) in the Brazilian Amazon has already been demonstrated. Malaria screening in blood banks is based on the selection of donors in respect to possible risks associated with travel or residence, clinical evidence and/or inaccurate diagnostic methods thereby increasing the probability of transfusion-transmitted infection. We evaluated the frequency of APCs in four blood services in distinct areas of the Brazilian Amazon region. DNA was obtained from 400 human blood samples for testing using the phenol-chloroform method followed by a nested-PCR protocol with species-specific primers. The positivity rate varied from 1 to 3% of blood donors from the four areas with an average of 2.3%. All positive individuals had mixed infections for Plasmodium vivax and Plasmodium falciparum. No significant differences in the results were detected among these areas; the majority of cases originated from the transfusion centres of Porto Velho, Rond��nia State and Macap��, Amap�� State. Although it is still unclear whether APC individuals may act as reservoirs of the parasite, efficient screening of APCs and malaria patients in Brazilian blood services from endemic areas needs to be improved.

Cytomegalovirus in colorectal cancer and idiopathic ulcerative colitis

Cytomegalovirus (CMV) is a genus in the family Herpesviridae that has been associated with gastrointestinal syndromes. In this work we looked for a possible association of CMV infection with colorectal cancer and ulcerative colitis (UC). Blood and enteric tissue samples of 14 patients with colorectal cancer and of 21 with UC were subjected to a nested-PCR that amplifies part of the gB gene of CMV and also to immunohistochemistry using a specific monoclonal antibody to IE 76kDa protein of CMV. CMV was detected by nested-PCR in the blood and/or the enteric tissue of nine (64.3%) colorectal cancer and 16 (76.2%) ulcerative colitis patients. In the immunohistochemistry it was observed that 12 (12/21, 57.1%) positive enteric tissue samples of patients with UC and none from patients with colorectal cancer (0/14) were positive to CMV. The positivity of CMV infections in the UC patient group (12/21, 57.1%) showed by both techniques, was significantly higher (p = 0.015) than that observed for colorectal cancer patients (2/14, 14.3%). These results suggest an association of ulcerative colitis with CMV infection of the enteric tissue.

Genotypic identification of Cryptosporidium spp. isolated from hiv-infected patients and immunocompetent children of S��o Paulo, Brazil

Cryptosporidium isolates identified in fourteen stool samples, collected from five HIV-infected patients and nine immunocompetent children, living in the Sate of S��o Paulo, Brazil, were submitted to a molecular analysis using a nested PCR followed of restriction fragment length polymorphism (RFLP), for genetic characterization. The analysis was based on digestion with RsaI restriction enzyme of a DNA fragment amplified from the Cryptosporidium oocyst wall protein (COWP) gene. Based on this analysis, four samples were identified as Cryptosporidium parvum, eight as Cryptosporidium hominis and two presented a profile that correspondedto Cryptosporidium meleagridis when compared to the standards used in the analysis. The use of molecular methods can be helpful to identify source of infections and risk factors related to Cryptosporidium infection in our communities.

Molecular characterization of Cryptosporidium spp. from HIV infected patients from an urban area of Brazil

Cryptosporidium spp. are important cause of enteric disease in humans, but may also infect animals. This study describes the relative frequency of several Cryptosporidium species found in human specimens from HIV infected patients in the S��o Paulo municipality obtained from January to July 2007. Sequence analysis of the products of nested-PCR based on small subunit rRNA and Cryptosporidium oocyst wall protein coding genes revealed 17 (63.0%) isolates of C. hominis, four (14.8%) C. parvum, five (18.5%) C. felis and one (3.7%) C. canis. These findings suggest that, in urban environments of Brazil, the cat adapted C. felis may play a potential role in the zoonotic transmission of cryptosporidiosis whereas the anthroponotic transmission of cryptosporidiosis caused by C. hominis seems to predominate.

Transmiss��o do v��rus citomeg��lico atrav��s do aleitamento materno em prematuros��

RESUMO: Nas ��ltimas quatro d��cadas, desenvolveram-se v��rios estudos, dispersos por todo o mundo, visando analisar a import��ncia da transmiss��o perinatal do CMV pelo leite materno, nos rec��m-nascidos prematuros e de baixo peso �� nascen��a. Comparando estes estudos, as taxas de incid��ncia de infec����o e doen��a s��o extremamente vari��veis, n��o havendo consenso entre os autores. Surgiu, assim, a necessidade de realizar a presente disserta����o, pioneira ao n��vel nacional, com o objectivo de determinar a incid��ncia da infec����o perinatal citomeg��lica, transmitida atrav��s do aleitamento materno a rec��mnascidos prematuros, e identificar as suas consequ��ncias cl��nicas. Para a elabora����o deste trabalho foram seleccionados todos os rec��m-nascidos com idade gestacional inferior a 35 semanas e respectivas m��es seropositivas para CMV, internados na Unidade de Cuidados Intensivos de Neonatalogia do Hospital de S��o Francisco Xavier, entre o per��odo de 1 de Outubro de 2010 e 31 Julho de 2011. Foram analisadas as urinas dos rec��m-nascidos e o leite materno das m��es na primeira, sexta e d��cima segunda semana p��s-parto, utilizando a t��cnica de Nested-PCR e, posteriormente, a PCR em Tempo Real, para determinar a carga viral do leite materno. Constatou-se que a aquisi����o da infec����o perinatal de CMV no rec��m-nascido prematuro ocorre com alguma frequ��ncia (40,5%), sendo muito prov��vel que a via de transmiss��o em 38,1% destes casos seja o leite materno infectado, n��o devendo esta ser desvalorizada. Relativamente ��s consequ��ncias cl��nicas, n��o foram observadas altera����es cl��nico-laboratoriais associadas �� infec����o citomeg��lica. Analisando os factores que condicionam a transmiss��o da infec����o citomeg��lica perinatal, estabeleceu-se uma correla����o entre a carga viral do leite materno e a transmiss��o do v��rus, permitindo deduzir que quanto maior a carga viral, maior o risco de transmiss��o. Finalmente, os resultados obtidos sugerem que o risco de transmiss��o da infec����o e suas consequ��ncias cl��nicas n��o justificam a contra-indica����o da amamenta����o, pois esta comporta, tamb��m, elevados benef��cios. ----------------ABSTRACT: In the last four decades, several studies were developed all over the world to analyze the importance of CMV perinatal transmission through mother��s milk in the preterm and low birthweight newborns. Comparing these studies, the infection and disease incidence rates are extremely variable, without agreement between the authors. The aim of this study, the first of the kind made in Portugal, is to define the rate of perinatal cytomegalovirus infection in preterm newborns via breastfeeding and its clinical consequences. All the newborns with gestational age below 35 weeks and their CMV seropositive mothers, admitted between the October 1, 2010 and July 31, 2011 in the Neonatology Intensive Care Unit of the S��o Francisco Xavier Hospital, were included in this study. Human breast milk and urine specimens were collected from mothers and their preterms infants around the 1st, 6th and 12th week after delivery and analyzed by Nested-PCR. The PCR in Real Time was used to determine the breast milk viral load. It was found that the CMV perinatal infection in preterm infants occurs in 40,5% of the cases and most likely 38,1% of these were infected via breastmilk and therefore this should not be overlooked. Considering the clinical consequences, no clinical and laboratory changes associated with cytomegalovirus infection were observed. Analyzing the factors that determine the perinatal transmission of the cytomegalovirus, it was established a correlation between breast milk viral load and viral transmission, allowing to conclude that the higher the viral load the greater the risk of transmission. Finally, the obtained results suggest that the risk of CMV infection and its clinical consequences don��t justify the breastfeeding contraindication because it also provides high benefits.

Efeito dos factores do hospedeiro e parasit��rios na susceptibilidade �� Mal��ria e gravidade da Doen��a

A mal��ria �� considerada como a doen��a parasit��ria mais s��ria em humanos, infectando cerca de 5 a 10% da popula����o mundial, estimando-se entre 300 a 600 milh��es de casos e mais de dois milh��es de mortes, anualmente. Apesar da severidade da doen��a, a compreens��o da variabilidade da resposta do hospedeiro �� infec����o (traduzida desde a infec����o silenciosa at�� formas cr��nicas da doen��a, passando por quadros cl��nicos potencialmente fatais), continua a ser um dos grandes desafios da investiga����o m��dica. V��rios factores gen��ticos parasit��rios ou do hospedeiro, estado imune e n��veis de exposi����o, contribuem para esta variabilidade, mas a sua import��ncia relativa para a carga total da doen��a tem sido pouco estudada. Entre outros, �� poss��vel salientar como fontes importantes de variabilidade na susceptibilidade �� mal��ria e gravidade da doen��a, factores intr��nsecos ao hospedeiro tais como polimorfismos gen��ticos relacionados com as c��lulas sangu��neas e factores parasit��rios como a composi����o da(s) popula����o(��es) parasit��ria(s) presentes na infec����o. Factores do hospedeiro humano relacionados com as c��lulas sangu��neas (drepanocitose e defici��ncia na glucose-6-fosfato desidrogenase - G6PD) t��m sido tradicionalmente estudados e relacionados com a gravidade da mal��ria causada por Plasmodium falciparum. Relativamente ��s popula����es parasit��rias, das cinco esp��cies que infectam humanos, P. falciparum continua a ser respons��vel pela mal��ria grave, apesar de muito recentemente alguma gravidade ser atribu��da a Plasmodium vivax. Sabe-se que nas mesmas ��reas outras esp��cies coexistem em muito maior preval��ncia, contrariando o que se pensava h�� algum tempo. Apesar de poucos estudos terem focado o tema das infec����es mistas, existem alguns relatos de que eventuais interac����es entre as diferentes esp��cies presentes simultaneamente no mesmo hospedeiro poderem afectar a susceptibilidade �� doen��a. Com o objectivo geral de avaliar o efeito e a contribui����o destes factores na susceptibilidade e gravidade da mal��ria, analisando e comparando tr��s grupos (estudo de caso-controlo) doentes com mal��ria grave (MG), doentes com mal��ria n��o-complicada (Mnc) e indiv��duos infectados assintom��ticos (IA), realiz��mos em Angola de 2007 a 2010, um estudo em sete das 18 prov��ncias com distintos n��veis de endemicidade. Foram obtidas 1.416 amostras de sangue perif��rico de 1.198 indiv��duos assintom��ticos e 218 doentes. O DNA obtido a partir destes isolados foi utilizado para detec����o da presen��a de variantes gen��ticos relacionados com os eritr��citos (drepanocitose ��� an��lise do gene HBB, defici��ncia G6PD ��� an��lise do gene G6PD, antig��nio Duffy-an��lise do gene DARC) e identifica����o das esp��cies de Plasmodium presentes, atrav��s de nested-PCR mediante a amplifica����o dos genes que codificam a subunidade menor do RNA ribossomal. Os resultados demonstraram preval��ncias superiores ��s anteriormente descritas em rela����o ��s seguintes esp��cies parasit��rias: P. falciparum 98,2% vs 92,0% e Plasmodium malariae 10,7% vs 1,0% e inferior em rela����o a P. vivax 2,5% vs 7,0%. Foi reconfirmada a presen��a de Plasmodium ovale (descrita anteriormente), mas n��o publicada em documentos oficiais e relatada pela primeira vez em Angola a presen��a de infec����es mistas (duplas e triplas) (15,7%) e de infec����o por P. vivax em indiv��duos Duffy-negativos (dados publicados). Relativamente aos polimorfismos relacionados com os genes HBB e G6PD e prov��vel associa����o com a protec����o �� mal��ria, os nossos resultados confirmam a associa����o do tra��o falciforme (heterozigotia HbS), com a protec����o �� doen��a (OR = 0,30; IC 95% 0,18-0,49; p<0,001). Contudo, n��o foi encontrada, quer nos indiv��duos hemizig��ticos, quer nos heterozig��ticos para o alelo G6PD (A-) nenhuma evid��ncia para a protec����o a mal��ria (MG e Mnc) (OR = 1,69; IC 95% 0,91-3,13; p=0,096). Os resultados desta investiga����o requerem um estudo mais aprofundado, com uma dimens��o amostral maior, necess��rio �� confirma����o da nossa observa����o.

First occurrence of an autochthonous canine case of Leishmania (Leishmania) infantum chagasi in the municipality of Campinas, State of S��o Paulo, Brazil

An autochthonous case of visceral leishmaniasis is reported in a dog (Canis familiaris) as an apparently natural infection in a non-endemic area. DNA obtained from spleen and liver samples produced the expected fragment in a Leishmania-specific rDNA-based nested-PCR assay. The PCR product, a 490 bp fragment, was sequenced and the nucleotide sequence was identical to that of Leishmania (Leishmania) infantum chagasi. These results are surprising since no autochthonous human or canine cases of visceral leishmaniasis have ever been reported in this municipality. This case suggests that natural transmission of this disease is occurring in this area.

Genetic diversity and primary resistance among HIV-1-positive patients from Maring��, Paran��, Brazil

The objective of this study is to identify subtypes of Human Immunodeficiency Virus type 1 (HIV-1) and to analyze the presence of mutations associated to antiretroviral resistance in the protease (PR) and reverse transcriptase (RT) regions from 48 HIV-1 positive treatment na��ve patients from an outpatient clinic in Maring��, Paran��, Brazil. Sequencing was conducted using PR, partial RT and group-specific antigen gene (gag) nested PCR products from retrotranscribed RNA. Transmitted resistance was determined according to the Surveillance Drug Resistance Mutation List (SDRM) algorithm. Phylogenetic and SimPlot analysis of concatenated genetic segments classified sequences as subtype B 19/48 (39.6%), subtype C 12/48 (25%), subtype F 4/48 (8.3%), with 13/48 (27.1%) recombinant forms. Most recombinant forms were B mosaics (B/F 12.5%, B/C 10.4%), with one C/F (2.1%) and one complex B/C/F mosaic (2.1%). Low levels of transmitted resistance were found in this study, 2/48 (2.1% to NRTIs and 2.1% for PI). This preliminary data may subsidize the monitoring of the HIV evolution in the region.

Diversidade gen��tica e resist��ncia natural ao Maraviroc em estirpes do v��rus da imunodefici��ncia humana Tipo 1 (HIV-1) em circula����o em utilizadores de drogas por via endovenosa na Grande Lisboa

RESUMO: O maraviroc (MVC) �� o ��nico anti-retroviral antagonista do co-receptor CCR5 licenciado e interage com as ansas transmembranares de CCR5, induzindo uma altera����o da sua conforma����o e impedindo a interac����o com gp120. O MVC �� activo apenas contra estirpes R5 de HIV-1, sendo utilizado em terapia de recurso. Neste trabalho, foi estudada a diversidade gen��tica da regi��o C2V3C3 do gene env de estirpes de HIV-1 de oxicodependentes por via endovenosa da Grande Lisboa, pesquisando-se tamb��m a presen��a de polimorfismos gen��ticos naturais. Foram utilizadas 52 amostras de plasma e para 35 destas foi amplificado por RT-nested PCR um produto de 565 pb. A an��lise filogen��tica revelou a seguinte distribui����o de gen��tipos: 23 B (incluindo, provavelmente, 2 CRF14_BG), 8 A, 3 G e 1 F1. Ap��s tradu����o, e por compara����o com a sequ��ncia consenso B, verificou-se uma elevada frequ��ncia de polimorfismos gen��ticos, sendo encontradas algumas ���assinaturas de amino��cidos��� relativas aos subtipos n��o-B. Realizou-se ainda uma pesquisa de locais de N-glicosila����o e a previs��o da utiliza����o de co-receptores (abordagem genot��pica), com recurso ��s regras 11/25 e da carga l��quida da ansa V3 e aos programas PSSM e geno2pheno[coreceptor]. Observou-se uma conserva����o gen��rica do n��mero de locais de N-glicosila����o e foram identificadas 5 sequ��ncias com tropismo X4 ou duplo. Por fim, com base na literatura, realizou-se uma pesquisa de polimorfismos gen��ticos associados a resist��ncia ao MVC presentes na ansa V3. Foi observado um n��mero elevado destas muta����es. A presen��a dos padr��es 11S+26V e 20F+25D+26V, num total de 3 sequ��ncias, �� relevante, visto estes estarem inequivocamente associados �� resist��ncia in vivo ao MVC. Apesar de n��o estar ainda definido um perfil de resist��ncia para o MVC, a presen��a das muta����es encontradas, em indiv��duos sem contacto pr��vio com o f��rmaco, trar�� implica����es relevantes na sua gest��o cl��nica, considerando a introdu����o do MVC na terapia de recurso.---------- ABSTRACT: Maraviroc (MVC) is the only CCR5 inhibitor licensed today. This drug interacts with the transmembrane helices of CCR5 co-receptor, inducing a conformation change of its extracellular loops and preventing the interaction with gp120. MVC is only active against R5 strains of HIV-1 and is currently used in salvage therapy. The genetic diversity of the env C2V3C3 region of HIV-1 strains from injecting drug users in the Greater Lisbon was studied, along with the presence of natural genetic polymorphisms. 52 plasma samples were used and the amplification by RT-nested PCR of a 565 bp-product was possible in 35 of them. The phylogenetic analysis revealed 23 sequences classified as subtype B (probably including 2 CRF14_BG), 8 A, 3 G and 1 F1. After translation, the presence of natural genetic polymorphisms was studied by comparison to a subtype B consensus. A high frequency of genetic polymorphisms was observed and significant ���amino acid signatures��� were found in association with non-B subtypes. A full characterization of the N-glycosylation sites was also performed and a coreceptor prediction (genotypic approach) was accomplished using the 11/25 and the V3 net charge rules and the programs PSSM and geno2pheno[coreceptor]. The number of N-glycosylation sites was generically preserved. Five sequences were defined as X4 or dual-tropic. Based on published data, a search for genetic polymorphisms, present in V3loop, associated to MVC resistance was finally undertaken. Several of such mutations were observed, being particularly interesting the presence of the patterns 11S+26V and 20F+25D+26V, in a total of 3 sequences, since these patterns have unequivocally been associated with MVC resistance in vivo. Although a resistance profile for MVC is not yet defined, the presence of these mutations in MVC-na��ve populations may have significant impact in their clinical management in the future, especially considering the introduction of this drug in salvage therapy.