Three postpartum antiretroviral regimens to prevent intrapartum HIV infection

BACKGROUND

The safety and efficacy of adding antiretroviral drugs to standard zidovudine prophylaxis in infants of mothers with human immunodeficiency virus (HIV) infection who did not receive antenatal antiretroviral therapy (ART) because of late identification are unclear. We evaluated three ART regimens in such infants.

METHODS

Within 48 hours after their birth, we randomly assigned formula-fed infants born to women with a peripartum diagnosis of HIV type 1 (HIV-1) infection to one of three regimens: zidovudine for 6 weeks (zidovudine-alone group), zidovudine for 6 weeks plus three doses of nevirapine during the first 8 days of life (two-drug group), or zidovudine for 6 weeks plus nelfinavir and lamivudine for 2 weeks (three-drug group). The primary outcome was HIV-1 infection at 3 months in infants uninfected at birth.

RESULTS

A total of 1684 infants were enrolled in the Americas and South Africa (566 in the zidovudine-alone group, 562 in the two-drug group, and 556 in the three-drug group). The overall rate of in utero transmission of HIV-1 on the basis of Kaplan-Meier estimates was 5.7% (93 infants), with no significant differences among the groups. Intrapartum transmission occurred in 24 infants in the zidovudine-alone group (4.8%; 95% confidence interval [CI], 3.2 to 7.1), as compared with 11 infants in the two-drug group (2.2%; 95% CI, 1.2 to 3.9; P=0.046) and 12 in the three-drug group (2.4%; 95% CI, 1.4 to 4.3; P=0.046). The overall transmission rate was 8.5% (140 infants), with an increased rate in the zidovudine-alone group (P=0.03 for the comparisons with the two- and three-drug groups). On multivariate analysis, zidovudine monotherapy, a higher maternal viral load, and maternal use of illegal substances were significantly associated with transmission. The rate of neutropenia was significantly increased in the three-drug group (P<0.001 for both comparisons with the other groups).

CONCLUSIONS

In neonates whose mothers did not receive ART during pregnancy, prophylaxis with a two- or three-drug ART regimen is superior to zidovudine alone for the prevention of intrapartum HIV transmission; the two-drug regimen has less toxicity than the three-drug regimen. (Funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development [NICHD] and others; ClinicalTrials.gov number, NCT00099359.).

HIV-1 binding and neutralizing antibodies of injecting drug users

Previous studies have demonstrated a stronger seroreactivity against some synthetic peptides responsible for inducing neutralizing antibodies in injecting drug users (IDU) compared to that of individuals sexually infected with HIV-1 (S), but the effectiveness in terms of the neutralizing ability of these antibodies has not been evaluated. Our objective was to study the humoral immune response of IDU by determining the specificity of their antibodies and the presence of neutralizing antibodies. The neutralization capacity against the HIV-1 isolate MN (genotype B), the primary HIV-1 isolate 95BRRJ021 (genotype F), and the seroreactivity with peptides known to induce neutralizing antibodies, from the V2 and V3 loops of different HIV-1 subtypes, were analyzed. Seroreactivity indicates that IDU plasma are more likely to recognize a broader range of peptides than S plasma, with significantly higher titers, especially of V3 peptides. Similar neutralization frequencies of the MN isolate were observed in plasma of the IDU (16/47) and S (20/60) groups in the 1:10 dilution. The neutralization of the 95BRRJ021 isolate was more frequently observed for plasma from the S group (15/23) than from the IDU group (15/47, P = 0.0108). No correlation between neutralization and seroreactivity with the peptides tested was observed. These results suggest that an important factor responsible for the extensive and broad humoral immune response observed in IDU is their infection route. There was very little difference in neutralizing antibody response between the IDU and S groups despite their differences in seroreactivity and health status.

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 ViroSeq 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.

Normal skin of HIV-infected individuals contains increased numbers of dermal CD8 T cells and normal numbers of Langerhans cells

Dysregulation of the skin immune system (SIS) could explain the high prevalence of skin disorders in HIV+ individuals. The present study was carried out to determine whether alterations in the cell population of SIS and epidermal immunoactivation occur in the normal skin of HIV+ individuals. Forty-five biopsies were taken from the normal upper arm skin of 45 HIV+ patients and of 15 healthy controls. HIV+ individuals were divided into three categories according to their CD4 cell blood count (<200, 200-499 and > or = 500/microl). Hematoxylin-eosin was used to stain tissue sections for morphological analysis and immunohistochemistry was used for the evaluation of the frequency of macrophages, Langerhans cells, and CD lymphocyte subsets. In addition, semiquantitative analysis of LFA-1, ICAM-1 and HLA-DR was determined in epidermal cells. Macrophages, Langerhans cells, and CD lymphocyte subsets did not differ significantly between any of the patient categories and the control group. When all HIV+ individuals were compared as a group to the control group, a significant increase in dermal CD8+ T lymphocytes (P < 0.01) and lower CD4-CD8 ratios (P < 0.01) were observed in the HIV+ individuals. Epidermal ICAM-1 and HLA-DR expression was negative in both HIV+ and normal skin biopsies. No evidence of a depletion of the SIS population or of epidermal immunoactivation in normal skin from HIV+ individuals was demonstrable, suggesting that alterations in the central immune system are not necessarily reflected in the SIS of HIV-infected patients.

Poor response to tuberculosis treatment with regimens without rifampicin in immunosuppressed AIDS patients

A prospective study was conducted on 79 advanced immunosuppressed AIDS patients from 1997 to 1999, during which nine cases of tuberculosis (TB) were diagnosed. The main clinical and laboratory characteristics and the response to TB treatment were reviewed. The clinical manifestations of TB were: pulmonary (six cases), extrapulmonary (two cases) and disseminated (one case). These patients were being treated with highly active antiretroviral treatment (HAART) and were not responding. In three cases an optional regimen without rifampicin (RMP) was indicated to maintain HAART during TB treatment. A clinical response to TB treatment (disappearance of fever) was observed in 6/9 patients during a mean of 73 days (SD = 96). The three unresponsive patients were those treated without RMP. A switch to TB regimens containing RMP was proposed and successful. In our study, though it was limited by a small sample size, the response to TB regimens without rifampin was poor in immunosupressed patients failing HAART.

Prevalence of mutations related to HIV-1 antiretroviral resistance in Brazilian patients failing HAART

BACKGROUND

Current guidelines for antiretroviral (ARV) therapy recommend at least triple-drug combination, the so-called highly active antiretroviral therapy (HAART). Not all patients respond to HAART and the development of drug resistance remains one of the most serious obstacles to sustained suppression of HIV.

OBJECTIVE

In an attempt to correlate the HIV therapeutic failure with reverse transcriptase (RT) and protease resistance mutations, we describe the ARV resistance profile in patients failing HAART in Brazil. We studied 267 Brazilian HIV-1 infected patients failing HAART looking for mutations in RT and protease genes. The mutation profile of the viruses infecting these individuals were deduced and correlated to laboratorial parameters.

STUDY DESIGN

Two different HIV-1 genomic regions were targeted for PCR amplification, the protease (pro) and pol RT (palm finger region) genes. The mutations related to drug resistance in RT gene was analyzed using a line probe assay (LIPA(R)) and pro amino acids positions 82 and 90 were screened through RFLP using HincII restriction digestion.

RESULTS

There was strong correlation between the mutation in the pro and RT genes and therapeutic failure. The main mutation found in RT gene was the M184V (48%) followed by T69D/N (47%), T215Y/F (46%), M41L (39%), and L74V (7%). In the pro gene the main mutation found was L90M (26%) followed by dual substitution in L90M and V82A (6%). All mutations profiles matched very well with the patients drug regimen.

CONCLUSIONS

This study has shown that 84.7% of HIV infected subjects failing HAART for more than 3 months presented viral genomic mutations associated with drug resistance.

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.

HIV-1 polymorphism: a challenge for vaccine development - a review

The perspective for the development of anti-HIV/AIDS vaccines became a target sought by several research groups and pharmaceutical companies. However, the complex virus biology in addition to a striking genetic variability and the limited understanding of the immunological correlates of protection have made this an enormous scientific challenge not overcome so far. In this review we presented an updating of HIV-1 subtypes and recombinant viruses circulating in South American countries, focusing mainly on Brazil, as one of the challenges for HIV vaccine development. Moreover, we discussed the importance of stimulating developing countries to participate in the process of vaccine evaluation, not only testing vaccines according to already defined protocols, but also working together with them, in order to take into consideration their local information on virus diversity and host genetic background relevant for the vaccine development and testing, as well as including local virus based reagents to evaluate the immunogenicity of the candidate vaccines.

Nutritional status impairments in HIV-infected patients are associated with increased TNF-alpha and IL-6 serum levels but not with viral load

BACKGROUND

Cytokines may alter metabolic pathways and contribute to malnutrition among human immunodefiency virus (HIV)-positive individuals.

PATIENTS AND METHODS

Tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), soluble IL-2 receptors (sIL-2R), beta2-microglobulin serum levels and plasma viral load of 45 HIV-positive patients were determined and correlated to nutritional status impairment. Patients were grouped by CD4 counts into categories I (< 200/microl), II (200-499/microl), III (> or = 500/microl). There were 15 healthy controls. A nutritional grading system, based on anthropometric and laboratory data, was devised. Scores ranged from 0 to 5 (eutrophic to malnutrition).

RESULTS

AIDS patients' cytokines and immune marker levels were significantly higher than those of the controls, but not always higher than those of other categories. AIDS patients had higher nutritional deficit grades than category III (p < 0.05) or the controls (p < 0.02) which, except for viral load, correlated with the parameters studied.

CONCLUSION

Nutritional status impairments in HIV-positive individuals were associated with immune activation but not with viral load.

Retrovirus infections in a sample of injecting drug users in Rio de Janeiro City, Brazil: prevalence of HIV-1 subtypes, and co-infection with HTLV-I/II

BACKGROUND

Retrovirus infections among injecting drug users (IDUs), a core at-risk population for both HIV-1 and HTLV-I/II infections in Brazil, were assessed within an ongoing cooperative research.

OBJECTIVE

The study assessed the seroprevalences of HIV-1 and HTLV-I/II infections, as well as the prevalence of HIV-1 subtypes in a sample of IDUs from Rio de Janeiro, Brazil. An attempt to evaluate HIV incidence was carried out using a dual 'sensitive/less sensitive' testing strategy.

STUDY DESIGN

Cross-sectional evaluation of 175 IDUs. Serostatus for HIV-1 and HTLV-I/II were established by enzyme-linked immunosorbent assays, and confirmed by western blot. The dual testing strategy aimed to estimate HIV-1 incidence rates. Differentiation between HTLV-I and -II was performed by western blot. DNA samples were polymerase chain reaction amplified by a nested protocol, and HIV-1 subtyping was determined by heteroduplex mobility assay.

RESULTS

Forty-six and 29 samples were found to be, respectively, positive for HIV-1 and HTLV-I/II, 15 of them co-infected by both viruses. Among HTLV-I/II-infected patients, 75.9% were infected by HTLV-I. Thirty-one HIV samples were identified as B subtype, with seven of them showing the typical "Brazilian B" pattern in the gp120 V3 loop, and ten were identified as F subtype. The use of less sensitive assays for HIV infection wrongly identified a deeply immunocompromised patient as an incident case.

CONCLUSION

Moderately high seroprevalences were found for both HIV-1 and HTLV-I/II infections, HIV-1/HTLV-I co-infections being of special concern. A non-statistically significant higher prevalence of F subtype was observed, when compared with the distribution of F/B subtypes among Brazilian patients from other exposure categories. No recent HIV-1 infections were detected, but a limitation of the "sensitive/less-sensitive" testing strategy was made evident.

Vertical HIV-1 transmission: importance of neutralizing antibody titer and specificity

Neutralization analyses were carried out with plasma from 132 volunteer human immunodeficiency virus (HIV)-1 infected women (76% pregnant, 24% with infants suspected for HIV-1 infection) collected between 1994 and 1998, against autologous and heterologous primary- and the reference HIV-1 MN isolates. A significantly lower percentage of HIV-1 transmissions was observed after 1996, parallel to a more intense antiretroviral treatment of infected pregnant women. HIV-1 isolation was significantly more frequent from peripheral blood mononuclear cells of mothers of infected children than mothers of uninfected children (P = 0.0065). Neutralization of autologous HIV-1 isolates was comparable for HIV-1 transmitters and nontransmitters' plasma, whereas neutralization of the reference isolate HIV-1 MN was more frequent at high titers for pregnant women who did not transmit HIV to their offspring compared to pregnant women who did. Although neutralization of heterologous primary HIV-1 isolates from HIV transmitters and non transmitters by transmitter plasma occurred with similar frequency, neutralization of isolates from transmitters was much more frequent when heterologous plasma from nontransmitters were used. Macrophage-tropic heterologous HIV-1 isolates were neutralized more frequently at higher titers by plasma from nontransmitters than from transmitters. The results obtained indicate that antiretroviral treatment, lack of success of HIV-1 isolation and high titers of antibodies able to neutralize macrophage-tropic viruses appear to be of importance for protection against HIV-1 vertical transmission for the group of patients studied.

Human immunodeficiency virus/acquired immunodeficiency syndrome and tropical diseases: a Brazilian perspective

The paper summarizes recent findings on the epidemiology and pathogenesis of human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/Aids), highlighting the role of co-infections with major tropical diseases. Such co-infections have been studied in the Brazilian context since the beginning of the Aids epidemic and are expected to be more frequent and relevant as the Aids epidemic in Brazil proceeds towards smaller municipalities and the countryside, where tropical diseases are endemic. Unlike opportunistic diseases that affect basically the immunocompromised host, most tropical diseases, as well as tuberculosis, are pathogenic on their own, and can affect subjects with mild or no immunosuppression. In the era of highly active anti-retroviral therapies (HAART), opportunistic diseases seem to be on decrease in Brazil, where such medicines are fully available. Benefiting from HAART in terms of restoration of the immune function, putative milder clinical courses are expected in the future for most co-infections, including tropical diseases. On the other hand, from an ecological perspective, the progressive geographic diffusion of Aids makes tropical diseases and tuberculosis a renewed challenge for Brazilian researchers and practitioners dealing with HIV/Aids in the coming years.

Molecular characterization of human immunodeficiency virus type 1-infected individuals from bolivia reveals the presence of two distinct genetic subtypes B and F

Thirty HIV-1-positive samples from Bolivia were genetically characterized on the basis of HMA and DNA sequencing, revealing the presence of B and F subtypes, in accordance with the molecular epidemiology pattern already described for other South American countries such as Brazil and Argentina. The interpatient divergence of subtype B Bolivian specimens was on average 14.2% (4.3-19.8%) at the nucleotide level, whereas the two unlinked subtype F samples (BO23 and BO29) were only 8.2% divergent, suggesting a more recent introduction of this subtype in the country. In our study group, which represents 13% of the HIV/AIDS cases already described in Bolivia as of May 1996, the transmission occurred more frequently through heterosexual exposures (46.7%), followed by homosexual (23.3%), bisexual (10%), intravenous drug use (3.3%), and vertical (3.3%); in one case the potential exposure category could not be defined (3.3%). No association could be established between exposure categories, gender, or clinical classification and subtype distribution in the Bolivian HIV/AIDS patients.

Sexual behaviour and infection rates for HIV, blood-borne and sexually transmitted infections among patients attending drug treatment centres in Rio de Janeiro, Brazil

A survey was carried out in 2 drug use treatment centres (TCs) in Rio de Janeiro, Brazil, to assess risk behaviours, HIV infection and other sexually transmitted infections/blood-borne infections (STIs/BBIs). Two hundred and twenty-five drug users (195 males and 30 females) were interviewed and clinically examined, and their blood and urine were tested for STIs/BBIs. Prevalences (%) for these infections were as follows--HIV: 0.9, hepatitis B virus (HBV): 14.7, hepatitis C virus (HCV): 5.8, syphilis: 5.3, gonorrhoea/chlamydia (CT/NG): 4.7. In bivariate analyses CT/NG infection was associated with younger age (P=0.003); current genitourinary symptoms (odds ratio [OR]=6.2) and a mainly illegal source of income (OR=9.1). Hepatitis C infection was associated with a history of ever having injected any drug (OR=19.6), and with each one of the injected drugs. After multiple logistic regression, lower educational level (adjusted odds ratio [AOR]=3.70) and 'ever having injected drugs' (AOR=3.69) remained as independent risk factors for hepatitis B infection. In conclusion, TCs must implement programmes directed towards the prevention of STIs/BBIs.

Search for evidence of a Th2 profile in HIV+ patients

BACKGROUND

Hypersensitivity dermatoses are common in human immunodeficiency virus-positive (HIV+) patients, particularly as the disease progresses. Studies have shown that a switch to T-helper 2 (Th2) might represent a turning point in HIV. This study investigated whether increases in the number of skin mast cells, immunoglobulin E (IgE) serum levels, and eosinophilia, involved in the Th2 response in allergic disease, might also be present in HIV+ patients. If so, these alterations might explain one of the mechanisms of skin hypersensitivity in these patients.

METHODS

Forty-five skin biopsies from the normal skin of the upper arm of HIV+ patients and 15 controls were included in the study. HIV+ individuals were classified into three equal categories according to their immunologic status: Category I (< 200/microL), Category II (200-499/microL), and Category III (> 500/microL). Anti-tryptase antibody was employed in tissue sections to show mast cells; IgE serum levels and eosinophils in peripheral blood count were investigated; delayed-type hypersensitivity (DTH) skin tests (candidin, trichophytin, and PPD 2U) were evaluated.

RESULTS

Normal cutaneous mast cell and eosinophil counts were the same in all categories and in the control group, but increased IgE levels (P < 0. 01) and DTH skin test anergy (P < 0.006) were observed among acquired immunodeficiency syndrome (AIDS) patients.

CONCLUSIONS

The density of skin mast cells in HIV infection was not modified in the course of the disease. Mast cells do not seem to be primarily responsible for triggering hypersensitivity dermatoses among AIDS patients, although data in support of the Th2 response, as seen in increased IgE serum levels and DTH anergy, are present.

HIV-1 diversity in Brazil: genetic, biologic, and immunologic characterization of HIV-1 strains in three potential HIV vaccine evaluation sites. Brazilian Network for HIV Isolation and Characterization

The Brazilian Network for HIV Isolation and Characterization was established for the surveillance of HIV variability in Brazil. Here, we report characterization of HIV strains and virus-specific immune responses from 35 clinical samples collected from three potential HIV vaccine sites. Three genetic subtypes of HIV-1 were identified by heteroduplex mobility assay (HMA) B (in 82.9% of the samples), F (14.3%), and C (2.9%). Phylogenetic analysis based on the C2V3/env DNA sequence from all 25 specimens examined was 100% concordant with HMA results. Four variants of subtype B with different tetrapeptides at the tip of the V3 loop were found: the GPGR motif (North American), GWGR motif (Brazilian B"), and two minor variants, GFGR and GPGS, as previously detected. No significant association was found between HIV-1 subtypes and the mode of transmission or biologic properties of HIV-1 isolates (derived from 88.6% of the specimens). Only 5 of 16 isolates studied were neutralized by the autologous sera. Consistent with previous results, no relation between viral subtype and peptide enzyme-linked immunosorbent assay (ELISA) seroreactivity or neutralization was evident. This study also demonstrated the effectiveness of the collaborative approach followed by Brazilian scientists when addressing a complex subject such as HIV variability.

HIV-1 subtyping in Salvador, Bahia, Brazil: a city with African sociodemographic characteristics

To investigate the prevalence of the HIV-1 subtypes in different populations from Salvador, Bahia, Brazil, blood samples from 72 HIV-1-seropositive injecting drug users (IDUs) and 62 individuals infected sexually were analyzed using the heteroduplex mobility assay (HMA). In the IDU group, 89.5% were classified as subtype B, 3% as subtype F, and 7.5% showed a B/F HMA profile. In the sexual transmission (ST) group, 95% were identified as B subtype, 3.4% showed a B/F profile, and 1.6% a B/C/E HMA profile. All Brazilian samples that showed multiple reactivities in the HMA analysis clustered on sequencing with B North American/ European HIV-1 isolates in the phylogenetic analysis, whereas the F subtypes clustered with F Brazilian HIV-I isolates. Serologic reactivities of IDU's sera were examined using a panel of synthetic V3 loop peptides representative of the different HIV-1 subtypes. No difference in serologic reactivity between F and B subtype plasma could be observed. Predominance of HIV-I subtype B was identified in both study groups, whereas subtype F was detected only among IDUs in a frequency lower than described for other Brazilian regions.

Anti-HIV-1 seroreactivity and HIV transmission route[R1]. The HEC/FIOCRUZ AIDS Clinical Research Group

BACKGROUND

Antibody binding assays carried out by our group have consistently indicated a higher reactivity of sera from male HIV-1 infected individuals. This study was carried out in order to analyze the importance of gender, route of transmission, disease progression and HIV-1 genotype in seroreactivity assays.

STUDY DESIGN

Specificity of antibody binding was studied in plasma of 247 HIV-1 seropositive individuals belonging to patient groups of pregnant women, injecting drug users (IDUs) and recent seroconvertors, resident in Rio de Janeiro, RJ. Recognition of synthetic peptides corresponding to antigenically important epitopes in the envelope of HIV-1 (gp41 immunodominant epitope, V3 loop, V2 loop and gp41 735-752 epitope) was determined.

RESULTS

The immunodominant gp41 peptide (amino acids 594-613, HIV-1 MN sequence) was recognized by 85% of all plasma tested. Reactivity with the gp41 735-752 peptide and gp120 V2 loop peptides was low but quite variable, being generally more often specific to a Brazilian V2 peptide used than to the HIV-1 MN derived V2 peptide. The overall recognition of the different V3 peptides tested varied from 41 to 76%. Patients with more advanced disease showed a more frequent reactivity with the peptides studied than did asymptomatic patients. Statistically significant differences in peptide recognition were observed by multiple logistic analyses comparing plasma derived from individuals infected by blood or sexual HIV transmission, adjusting for disease progression and gender. Plasma from individuals infected by sexual transmission showed lower peptide recognition than did plasma from individuals infected through HIV positive blood. Association attempts between seroreactivity and genotype indicated that plasma derived from patients infected with HIV-1 of the F subtype showed highest recognition of heterologous V3 peptides, as well as a slightly more frequent recognition of the non-V3 peptides tested. Recognition of homologous peptides was generally higher than recognition of heterologous peptides. Differences were most pronounced between the prototypical HIV-1 B subtype and the Brazilian B" variant of this subtype but almost non-existent between the HIV-1 B and F subtypes.

CONCLUSIONS

Individual gender was shown to be a confounder when investigating the relationships of peptide reaction to HIV-1 route of transmission through multivariate statistical methods: patients infected by blood transmission (IDU) present higher frequency of peptide recognition than individuals infected by sexual HIV-1 transmission. Plasma from individuals infected with the B" variant (GWG) of B subtype HIV-1 showed lower heterologous peptide recognition than that from HIV-1 B (GPG) or F infected individuals.

Functional activity of alveolar and peripheral cells in patients with human acquired immunodeficiency syndrome and pulmonary tuberculosis

We compared the peripheral and pulmonary response to assess the phagocytic activity of monocytes/macrophages and neutrophils and the lymphoproliferative response (LPR) against Mycobacterium tuberculosis antigens from 21 AIDS patients, presenting at diagnosis with active pulmonary tuberculosis (TB), other non-TB pulmonary infection, or no pulmonary infection, as well as patients with active pulmonary TB and healthy control subjects. Alveolar lymphocyte analysis demonstrated that AIDS/TB patients had more markedly reduced percentages of CD4(+) lymphocytes than AIDS/TB patients and an increase in the percentage of CD8(+) lymphocytes, probably reflecting the impairment of CD4(+) T lymphocytes in peripheral blood at the lungs. Moreover, alveolar lymphocytes from AIDS/TB patients demonstrated a two- to fourfold decrease in LPR against M. tuberculosis antigens. Interestingly, it was observed an enhanced migration of natural killer cells to the lungs in all patients group. The phagocytic activity in alveolar macrophages and neutrophils showed that AIDS/TB patients had a twofold decreased capacity to ingest inert particles compared with AIDS patients. Comparing the alveolar and peripheral lymphocyte number and functional activity to M. tuberculosis-antigens it was possible to demonstrate that in both sites these cells had similar profile. However, the innate immune response in lungs showed a reduced activation in the presence of HIV infection, regarding the M. tuberculosis coinfection. These findings suggest that the advanced impairment of CD4(+) T lymphocyte in HIV-1 infection may lead to a deactivation of alveolar macrophages, enhancing bacilli burden and HIV replication in the lungs and furthering dissemination.

Molecular epidemiology of HIV-1 in Brazil: high prevalence of HIV-1 subtype B and identification of an HIV-1 subtype D infection in the city of Rio de Janeiro, Brazil. Evandro Chagas Hospital AIDS Clinical Research Group

HIV-1-positive individuals were recruited from January 1993 to December 1996 from several cohorts receiving follow-up in the city of Rio de Janeiro, Brazil, to evaluate HIV-1 genetic variability and the potential association with modes of transmission. HIV-1 subtyping was carried out using the heteroduplex mobility assay (HMA), and those samples corresponding to the typical Brazilian subtype B variant were further identified based on the Fok I restriction fragment length polymorphism (RFLP). DNA sequencing was performed to evaluate one case of subtype D infection. From the 131 HIV-1-positive individuals analyzed, 106 (80.9%) could be identified as infected by subtype B and 20 (15.3%) by subtype F. One of the samples (0.8%) was classified as subtype D. DNA samples from 4 patients (3.0%) did not yield polymerase chain reaction (PCR)-amplified products to be typed. Based on the Fok I RFLP, 39 of the 106 subtype B samples (37%) were identified as corresponding to the typical Brazilian subtype B variant containing the GWGR motif at the tip of the V3 loop. No statistically significant association could be detected between HIV-I subtypes and modes of transmission, exposure categories, or gender. This is the first reported case of HIV-1 subtype D infection in Brazil.

Neutralization susceptibility of B subtype variant B" primary HIV-1 isolates. The HEC/FIOCRUZ AIDS Clinical Research Group

Susceptibility to autologous and heterologous neutralization of primary human immunodeficiency virus (HIV)-1 isolates belonging to subtype B, to the B"-variant of subtype B or to subtype F from infected individuals residing in Rio de Janeiro was assayed. A lower infectivity of the B"- and F isolates when compared to the classical B-subtype HIV-1 isolates was observed. Comparisons of neutralization susceptibilities were carried out for 19 B-subtype, 11 B"-variant and two F-subtype HIV-1 isolates with plasma from autologous and heterologous samples. Frequency of autologous neutralization was slightly lower for B-subtype isolates in comparison to B"-variant isolates. Heterologous intra-subtype neutralization was significantly lower for B-subtype than for the B"-variant or the F-subtype isolates. While B-subtype isolates were neutralized by most anti-F-subtype plasma, F-subtype isolates, although most susceptible to F-subtype antibodies, were highly susceptible to neutralization by anti-B-subtype antibodies. Cross-neutralization for B"-variant and B-subtype isolates was not as extensive as observed for B- and F-subtype isolates. However, the results presented indicate a quite extensive cross-neutralization between Brazilian HIV-1 isolates.

HIV specific humoral immune response in Rio de Janeiro, Brazil. The HEC/Fiocruz AIDS Clinical Research Group

Efforts to characterize HIV-1 polymorphism and anti-HIV immune response are being made in areas where anti-HIV/AIDS vaccines are to be employed. Anti-HIV-1 humoral immune response is being studied in infected individuals residents in Rio de Janeiro, in distinct cohorts involving recent seroconvertors, pregnant women or intravenous drug users (IDU). Comparative analyses of specificity of antibody response towards epitopes important for anti-HIV-1 immune response indicate quantitative differences between cohorts, with an exceptionally strong response in IDUs and weakest response in pregnant women. However, a comparative analysis between pregnant women cohorts from Rio de Janeiro and Rio Grande do Sul indicated an even lower response (with exception of the anti-V3-C clade peptide recognition) for the southern cohort. Studies analysing the immune function of the humoral response indicate a quite elevated occurrence of antibodies capable for neutralizing heterologous primary HIV-1 isolates from Rio de Janeiro. Attempts to correlate seroreactivity with HIV-1 neutralization with respect to HIV-1 polymorphism were not very successful: while the Brazilian B clade B " variant could be recognized by binding assays, no significant distinction of HIV-1 clades/variants was observed in viral neutralization assays.

Improvement of the lymphoproliferative immune response and apoptosis inhibition upon in vitro treatment with zinc of peripheral blood mononuclear cells (PBMC) from HIV+ individuals

Clinical improvement has been described in AIDS patients submitted to zinc therapy, but the mechanisms involved are not well understood. In order to evaluate the effect of the zinc ions in the enhancement of the immune response, we tested its role in the lymphoproliferative response to a mitogen, as well as in the prevention of apoptosis. The mitogenic effect of zinc (10(-4)M ZnCl2) on the lymphocyte proliferative response was observed in healthy controls as well as in HIV-1+ asymptomatic individuals. Very low stimulation index could be observed in AIDS patients (CD4+<200/mm3). However, zinc treatment of phytohaemagglutinin (PHA; 5 microg/ml)-stimulated PBMC cultures significantly enhanced 3H-thymidine incorporation in both asymptomatic and symptomatic groups. A decreased percentage of apoptotic cells could be identified in cell cultures from HIV-1+ individuals submitted to zinc treatment compared with cells treated only with PHA, as detected by both flow cytometry and agarose gel electrophoresis. Further studies with zinc supplementation associated to anti-retroviral therapy would be of great interest to evaluate the in vivo role of this oligoelement in the improvement of the immunological functions of HIV-1-infected individuals and AIDS patients.

Correlation between susceptibility of primary HIV-1 isolates to autologous and heterologous neutralizing antibodies. Hospital Evandro Chagas AIDS Clinical Research Group

OBJECTIVE

To study the susceptibility of primary HIV-1 isolates towards autologous and heterologous neutralizing antibodies (NAb).

DESIGN

Blood was collected and primary HIV-1 isolated from individuals residing in Rio de Janeiro, Brazil, in all phases of disease.

METHODS

Primary HIV-1 isolates were incubated with autologous or heterologous plasma and neutralization of infection of freshly pre-stimulated normal human peripheral blood mononuclear cells was assayed in parallel to median infectious dose determinations in the absence of antibodies. Levels of HIV-1 p24 antigen were used for evaluation of viral neutralization.

RESULTS

Autologous neutralization (75%) was observed for 13 (52%) out of 25 of the primary HIV-1 isolates, and 15 (71%) out of 21 isolates were susceptible to 75% heterologous neutralization by at least one-half of the heterologous plasma tested. Primary HIV-1 isolates susceptible to autologous NAb showed a higher susceptibility towards neutralization by heterologous NAb than isolates that could not be neutralized by the autologous plasma (P = 0.049). The susceptibility of the primary HIV-1 isolates towards neutralization by heterologous NAb was significantly higher for isolates derived from men (P = 0.001), and for isolates obtained from individuals infected through homo-/bisexual risk behaviour in comparison with those infected through heterosexual HIV-1 transmission (P = 0.03).

CONCLUSIONS

Susceptibility of primary HIV-1 isolates to autologous and heterologous neutralization was significantly correlated, indicating that escape mutants may become resistant not only to autologous but also to heterologous NAb.

Identification of human immunodeficiency virus type 1 envelope genes recombinant between subtypes B and F in two epidemiologically linked individuals from Brazil

Sequence analysis of a human immunodeficiency virus type 1 env gene PCR amplified from a Brazilian woman's peripheral blood mononuclear cell DNA (sample RJIO1) showed that it was likely to have been derived from a double recombination event between human immunodeficiency virus type 1 subtypes B and F. The major portion of the gp120 coding sequence belonged to the B lineage, but a segment of the C2 to V3 region (approximately 135 nucleotides) clearly associated with sequences of the F lineage. The subtype F-like segment had 15 noncontiguous signature nucleotides in common with Brazilian subtype F sequences that were not found, or were rare, in subtype B sequences. In contrast, this same segment had only 3 signature nucleotides shared with subtype B sequences and not present in the Brazilian subtype F sequences. Phylogenetic analysis, amino acid signature pattern analysis, and the pattern of synonymous mutations all supported the hypothesis of a recombinational origin of the RJIO1 sequence. Related recombinant genes were also detected in peripheral blood mononuclear cell DNA obtained from the woman's recent sexual partner, indicating that the recombination event probably occurred at some previous time in the chain of virus transmission. Divergent viral sequences in the V3 region were found in the male sexual partner, while a relatively homogeneous viral population was detected in the woman, consistent with her recent infection.

Analysis of antibody specificity against the third variable region of the envelope glycoprotein gp120 of HIV-1 in plasma from HIV-1-positive individuals residing in Brazil

1. Antibody specificity for the principal neutralization domain (PND) of the human immunodeficiency virus type 1 (HIV-1) was studied in plasma from 122 HIV-1-infected individuals residing in Brazil. 2. Using 8 overlapping sequential pentadecapeptides corresponding to the third variable region (V3) of 5 different HIV-1 isolates in an enzyme-linked immunosorbent assay (ELISA), a preferential recognition of the peptides with amino acid sequences corresponding to the HIV-1 isolates IIIB and MN (maximal reactivities of 60-70%) compared to the isolates SC, WMJ-2 or RF (maximal reactivities below 60%) was observed. 3. A difference was observed in the overall reactivity pattern to HIV-1 SC peptides of plasma collected from individuals residing in the Brazilian states of Rio de Janeiro and Bahia. However, a statistically significant increased recognition by Bahian plasma was only observed for the HIV-1 SC C55 peptide. 4. The mean CD4/CD8 ratio of the group of plasma with an isolate-restricted recognition of peptides (0.522 +/- 0.074) was significantly lower than that of the total group of plasma (1.00 +/- 0.18).

V3 region polymorphisms in HIV-1 from Brazil: prevalence of subtype B strains divergent from North American/European prototype and detection of subtype F

Viral DNA sequences were determined over the V3 region of env from 28 infected individuals living in the high HIV-1 prevalence Brazilian cities of Rio de Janeiro and São Paulo. Twenty-six belonged to envelope sequence subtype B, prevalent in North America and Europe, and one was classified as subtype F, found recently in Brazil and in Romania (one appeared to be a B/F recombinant). Octameric sequences at the tip of the subtype B V3 loops were variable and distinct from those prevalent in North America and Europe. The GPGR motif, prevalent in North American/European strains, was found in only 8 (28.5%) sequences, whereas GWGR was found in 12 (43%) and novel sequences in 8 (28.5%). Brazilian subtype B sequences also diverged from the consensus North American/European strains over the remainder of the V3 loop. These results suggest that Brazilian HIV-1 B strains may have important antigenic differences from prototype subtype B strains currently being evaluated for use in HIV vaccines. These results should be taken into account for future vaccine programs in Brazil.

Leptospirosis patient with AIDS: the first case reported

A case of renal icterohemorrhagic leptospirosis involving a patient with acquired immunodeficiency syndrome (AIDS) is reported. Despite the low levels of CD4+ T lymphocytes, the clinical course of leptospirosis was similar to that observed in non-immunodepressed patients, and no worsening of AIDS occurred due to the infection by the spirochete. Serologic conversion was observed in the microscopic agglutination test, with maximum titer of 1:3,200. The patient had positive urine cultures for Leptospira interrogans for two months, whereas blood cultures were negative.

Restriction fragment length polymorphism and evolution of the mouse immunoglobulin constant region gamma loci

Genomic DNA from twelve laboratory mouse strains, in addition to 21 wild-derived strains belonging to different taxa (Mus musculus domesticus, Mus musculus musculus, Mus spretus, Mus macedonicus, and Mus spicilegus) and four mouse strains that are evolutionarily more distant, were analyzed by Southern blot for polymorphism of the Ig heavy chain constant region gamma isotype (Igh-C gamma) and for the distribution of the duplicated Igh-1 (C gamma 2 alpha) haplotype. Distinct allelic forms of each Igh-C locus could be defined by restriction fragment length polymorphism (RFLP). In laboratory mouse strains RFLP proved to be more sensitive in the detection of Igh-4 (C gamma 1) alleles than serological methods. Taq I digestion allowed the definition of two alleles in the Igh-8 (C gamma 3) locus, which is absolutely conserved at the protein levels. More extensive RFLP could be found in wild strains belonging to the subgenus Mus and in the evolutionarily more distant Mus species belonging to other subgenera. In previous studies we have shown that the Igh-1 locus is duplicated in M. m. musculus subspecies. We now extend this observations to the wild mouse strains belonging to M. spicilegus and M. macedonicus species and to the evolutionarily more distant wild mouse strain Mus pahari (subgenus coelomys), which is thought to have diverged from domestic mice about 5 million years ago. In addition, we found a similar RFLP pattern in ten of 18 wild mice trapped in India, suggesting that the haplotype containing the two Igh-1-like genes, organized in tandem as distinct isotypes, is widely spread in natural populations. The evolution of murine Igh-C gamma-encoded isotypes is also discussed.

Molecular and biological diversity of HIV-1 in Brazil

To determine the genomic polymorphism and biological properties present in HIV-1 Brazilian isolates, we analyzed five viral isolates obtained from patients residing in Rio de Janeiro (P1 and P5), São Paulo (P3) and Bahia (P2 and P4) states. For each viral isolate in vitro characteristics such as replication rate, syncytium-inducing capacity and cell death were observed in lymphoblastoid (H9, CEM and peripheral blood mononuclear cells) as well as monocytoid (U937) cells. In addition, the evaluation of the restriction fragment length polymorphism of these isolates was also performed using a panel of endonucleases such as Hind III, Bgl II, Sac I, Pst I, Kpn I and Eco RI. One of the isolates (P1), showed the highest phenotypic and genotypic divergence, when compared to others. The results found suggest a HIV heterogeneity in Brazil similar to that already described in other regions of the world.

Further evidence that BALB/c and C57BL/6 gamma 2a genes originate from two distinct isotypes

Gene conversion by the corresponding gamma 2b gene has been proposed to explain the multiple differences between the nucleic acid sequences of BALB/c (Igh-1a) and C57BL/6 (Igh-1b) gamma 2a immunoglobulin allelic genes. However, genetic analysis indicates that duplicated forms of gamma 2a genes are not only present in Eastern Asia, but also in European wild mouse populations which suggests a widespread phenomenon. In order to verify whether the gamma 2a-related isotypic genes, namely gamma 2c and gamma 2a, could correspond to those present as alleles in domestic mice (Igh-1b and Igh-1a), a genomic library from Mus m.musculus strain (MAI) was constructed. Extensive mapping of the recombinant phages and Southern blot analysis with several restriction enzymes gave the complete organization of these loci: gamma 2b (18 kb) gamma 2c (17 kb) gamma 2a (14 kb) epsilon. The homology in flanking, coding and intervening region sequences indicates that MAI gamma 2c and gamma 2a related genes correspond to C57BL/6 and BALB/c Igh-1 alleles respectively. Also, Southern blot analysis using several probes derived from exonic and intronic regions between gamma 2b and gamma 2a genes shows a 2.0- to 3.0-kb difference in the distance between gamma 2b and gamma 2a genes of BALB/c strain as compared to C57BL/6. Taken together, these results indicate that BALB/c and C57BL/6 gamma 2a genes could originate from different isotypes.

Complexity, polymorphism, and recombination of mouse T-cell receptor alpha gene families

Genomic DNA from a large panel of inbred strains of mice were hybridized sequentially with 15 V alpha, 2 V delta, 1 C alpha, and 1 C delta probes. Most of the V alpha probes detected a high degree of polymorphism and have allowed the definition of five mouse T-cell receptor alpha (Tcr alpha) haplotypes. One of these haplotypes (Tcre alpha) appears to arise from a recombination between the Tcrb alpha and Tcra alpha haplotypes, the latter being the most frequently found in the conventional inbred strains. This recombination event clearly indicates that the members of at least 11 V alpha sub-families are not closely linked but highly interspersed with one another on chromosome 14.

Trypanosoma cruzi: identification of specific epimastigote antigens by human immune sera

Soluble antigens from epimastigotes of Trypanosoma cruzi were analyzed by western blot in terms of their reactivity with sera from patients with Chagas' disease. In addition, sera from patients with visceral (AVL) and tegumental leishmaniasis (ATL) were also tested in order to identify cross-reactivities with Trypanosoma cruzi antigens. Twenty eight polypeptides with molecular weights ranging from 14 kDa to 113 kDa were identified with sera from Chagas' disease patients. An extensive cross-reactivity was observed when sera from human visceral leishmaniasis were used, while only a slight cross-reaction was observed with sera from tegumental leishmaniasis. On the other hand, 10 polypeptides specifically reacting with sera from Chagas' disease patients were identified. Among them, the antigens with molecular weights of 46 kDa and 25 kDa reacted with all sera tested and may be good candidates for specific immunodiagnosis of Chagas' disease.

The mouse Igh-1a and Igh-1b H chain constant regions are derived from two distinct isotypic genes

Genetic and structural analyses of the mouse genes encoding constant region of immunoglobulin subclass (Igh-C) have shown that recombination is rare within this cluster which is inherited as a set designated the Igh haplotype. Recent molecular analyses have demonstrated that either DNA exchanges or gene duplications have probably occurred during the evolution of this set of genes. In order to assess the generality of the duplication processes, the presence and expression of two allelic forms of the Igh-1 (gamma 2a) gene (Igh-1a and Igh-1b) were examined in a large panel of wild mice belonging to Mus musculus domesticus and Mus musculus musculus species. Our data indicate that certain M. m. domesticus animals and most animals in the M. m. musculus group coexpress the two allelic forms of Igh-1. Moreover, genetic studies show that these two immunoglobulin types are encoded by tandemly arranged genes. We propose that wild mice, from which laboratory mice are derived, carry three isotypic gamma 2 genes (Igh-1a, Igh-1b, Igh-3), and these have given rise to the two isotypes seen in laboratory strains by a deletion/insertion mechanism.

Human visceral leishmaniasis: analysis of the specificity of humoral immune response to polypeptides of Leishmania donovani chagasi

Soluble antigens from Leishmania donovani chagasi were studied in terms of their ability to react with sera from human visceral leishmaniasis. Thirty-six polypeptides, with molecular weights ranging from 14,400 to 123,000 were demonstrated by Western blot analysis. An extensive cross-reactivity with sera from patients with cutaneous leishmaniasis and Chagas' disease also was observed. Two polypeptides (Mr 119,000 and 123,000) reacted with all the sera from visceral leishmaniasis patients. When they were electroeluted from gels and evaluated with respect to specificity to the L. donovani chagasi subspecies, these components were expressed in all strains of Leishmania tested, but not in those of Trypanosoma cruzi. These results indicated that these components are shared by Trypanosomatidae of genus Leishmania. The eluted polypeptides did not react with sera from patients with Chagas' disease, indicating the feasibility of using purified antigens to discriminate between the humoral immune responses in T. cruzi and Leishmania infections.

Immunopathological aspects of experimental Trypanosoma cruzi infection: correlation of immune complexes and other serological features with muscle lesions during the infection

The pathogenesis of the tissue lesions observed in American trypanosomiasis (Chagas' disease) seems to depend on a variety of mechanisms. The present study was dedicated to the investigation of the evolution of muscle lesions and its relationship with immunological and parasitological parameters. Mice were infected i.p. with 10(5) blood forms of Trypanosoma cruzi (Columbian strain). A progressive increase in parasitaemia was observed which correlated with an increase in serum levels of IgG and IgM Trypanosoma-specific antibodies. Immune complex like material was detected in the serum (125I-C1q binding assay) on day 8 and reached maximum level between day 21 and 28. A concomitant fall in C3 levels was also observed. Inflammatory lesions and parasites were first observed in the striated muscle 2 weeks after infection. The cellular infiltrates involved macrophages and lymphoid cells; later on (week 3 onwards), intense necrosis appears and at the same time immunoglobulin and complement deposition were observed. These observations may indicate that, in addition to the cellular immune response, humoral mechanisms could contribute to the worsening of tissue lesions.

Antigenic analysis of Trypanosoma cruzi strains by crossed immunoelectrophoresis: demonstration and isolation of antigens particular to some strains

Antigenic differences among soluble extracts of Y, CL, SF, and Colombian strain epimastigotes of Trypanosoma cruzi have been demonstrated by crossed immunoelectrophoresis with an intermediate gel containing the heterologous antiserum. Using crossed immunoelectrophoresis with the homologous antiserum, over 30 precipitin lines could be demonstrated for each strain and, even though marked differences were observed in experimental infections, the strains shared a significant number of antigens. In addition, some strain-particular antigens were isolated using affinity chromatography. These antigens could be valuable in the study of biological, immunological, and pathological characteristics of experimental and natural T. cruzi infections.

[Particular antigens of strains of Trypanosoma cruzi: demonstration by two-dimensional immunoelectrophoresis]

Os extratos solúveis das cepas Y, São Felipe e Colombiana do Trypanosoma cruzi foram analisados contra seus antissoros homólogos e heterólogos por imunoeletroforese bidimensional e imunoeletroforese bidimensional com gel intermediário. Os resultados revelaram a existência de pelo menos 35 linhas de precipitação na cepa Y (32 de migração anódica e três de migração catódica), 24 linhas de precipitação anódica na cepa São Felipe e 22 na cepa Colombiana. Estas duas últimas cepas não apresentaram antígenos de migração catódica. Estes antígenos de migração catódica foram considerados "particulares" a cepa Y uma vez que quando testados contra antissoros heterólogos não observamos linhas de precipitação. Através do uso da imunoeletroforese bidimensional com gel intermediário foram evidenciados cinco antígenos particulares à cepa Y quando comparada à São Felipe e oito quando comparada à cepa Colombiana. A cepa São Felipe mostrou um único antígeno particular quando comparada à cepa Colombiana porém, não se evidenciou nenhum antígeno particular quando a cepa São Felipe foi analisada contra o antissoro da cepa Y. A cepa Colombiana não demonstrou nenhum antígeno particular nem quando comparada à cepa Y nem à São Felipe. Nossos resultados revelam que cepas pertencentes a diferentes tipos quanto ao comportamento morfobiológico e histopatológico também demonstram uma acentuada diferença quanto a seus componentes antigênicos.