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.

Efficacy of an enzyme-linked immunosorbent assay as a diagnostic tool for schistosomiasis mansoni in individuals with low worm burden

IgM-ELISA is an immunoenzymatic method useful for detection of IgM antibodies against a fraction of Schistosoma mansoni adult worm antigen (AWA) that is soluble in trichloroacetic acid (AWA-TCA). This method was applied to three groups of individuals with different clinical and epidemiological characteristics, and the results compared with those obtained by other diagnostic methods: immunofluorescence test for detection of IgM antibodies (IgM-IFT) or IgG antibodies (IgG-IFT), ELISA for detection of IgG antibodies (IgG-ELISA), and two parasitological methods, Kato-Katz and miracidium hatching. The IgM-ELISA presented a sensitivity of 98%, when the parasitologic fecal examination was defined as reference diagnostic method, and a specificity of 98 and 97.3%, respectively for the group of clinically healthy individuals and other helminth carriers. A comparative analysis between the results of IgM-ELISA and those obtained by other serologic tests showed a good degree of agreement, with Kappa indices ranging from 0.95 to 0.98. The diagnostic efficacy of 97.8%, as determined with schistosomiasis patients with low parasitic burden, suggests the excellent performance of the IgM-ELISA and its usefulness for the diagnosis of schistosomiasis when applied in low endemic areas.

Taeniosis-cysticercosis complex in individuals of a peasants' settlement (Teodoro Sampaio, Pontal of Paranapanema, SP, Brazil)

In order to evaluate the taeniosis-cysticercosis complex in a population of a peasants' settlement, located at Teodoro Sampaio, state of São Paulo, Brazil (longitude 52° 36'12 ", latitude 22° 17'12 ") a series of laboratory markers were determined. After signing an informed consent, participants answered a standardized questionnaire. To determine anti-Taenia solium cysticercus antibodies, the samples were tested by enzyme linked immunoabsorbent assay using 18-and 14-kDa antigen proteins from vesicular fluid of Taenia crassiceps (VF-Tcra). The reactive and inconclusive ELISA samples were tested by immunoblotting. Total IgE levels were determined by chemmiluminescence's assay and hemogram by flow cytometer flux counter. A total of 84 individuals, 5.9% presented anti-T. solium cysticercus antibodies in ELISA and 3.6% were strongly reactive in the 18/14 kDa immunoblotting confirmatory test. All of the individuals with positive antibodies showed elevated Total IgE levels. We conclude that the frequency of anti-T. solium cysticercus antibodies in this population is higher than other regions considered endemic in São Paulo. Thus, it is important to carry out surveys in Peasants' settlement areas with the objective of establishing public health measures for prevention and control of infectious diseases such as taeniosis-cysticercosis.

Clinical forms of Trypanosoma cruzi infected individuals in the chronic phase of Chagas disease in Puebla, Mexico

In Mexico, despite the relatively high seroprevalence of Trypanosoma cruzi infection in humans in some areas, reported morbidity of Chagas disease is not clear. We determined clinical stage in 71 individuals seropositive to T. cruzi in the state of Puebla, Mexico, an area endemic for Chagas disease with a reported seroprevalence of 7.7%. Diagnosis of Chagas disease was made by two standardized serological tests (ELISA, IHA). Individuals were stratified according to clinical studies. All patients were submitted to EKG, barium swallow, and barium enema. Groups were identified as indeterminate form (IF) asymptomatic individuals without evidence of abnormalities (n = 34 cases); those with gastrointestinal alterations (12 patients) including symptoms of abnormal relaxation of the lower esophageal sphincter and absent peristalsis in the esophageal body, grade I megaesophagus, and/or megacolon; patients with clinical manifestations and documented changes of chronic Chagas heart disease who were subdivided as follows: mild (8 patients) - mild electrocardiographic changes of ventricular repolarization, sinus bradychardia); moderate (6 patients) - left bundle branch block, right bundle branch block associated with left anterior fascicular block); severe (8 patients) - signs of cardiomegaly, dilated cardiomyopathy); and the associated form (3 cases) that included presence of both cardiomyopathy and megaesophagus. These data highlight the importance of accurate evaluation of the prevalence and clinical course of Chagas disease in endemic and non-endemic areas of Mexico.

Schistosoma mansoni antigen-driven interleukin-10 production in infected asthmatic individuals

Asthmatics infected with Schistosoma mansoni have a less severe course of asthma and an inhibition of the Th2 inflammatory response that seems to be mediated by interleukin (IL-10). The objective of this study was to evaluate the capacity of some S. mansoni antigens to stimulate IL-10 production in vitro by cells of asthmatic infected individuals. Peripheral bloods mononuclear cells were stimulated with the S. mansoni recombinant antigens Sm22.6, Sm14, P24, and PIII antigen. IL-10 was measured in the supernatants of cultures. As the recombinant antigens were cloned in Escherichia coli, we blocked contaminant endotoxin with polymyxin B added to the cultures. We demonstrated that all antigens used drove high production of IL-10 in S. mansoni infected individuals (n = 13, 408 ± 514 and 401 ± 383 pg/ml, 484 ± 245 pg/ml, 579 ± 468 pg/ml, respectively). In asthmatics infected with S. mansoni (n = 21) rP24 induced higher levels of IL-10 (565 ± 377 pg/ml) when compared to PIII, rSm14 and rSm22.6 (184 ± 209 pg/ml; 292 ± 243 pg/ml; 156 ± 247 pg/ml, respectively). Conclusion: the S. mansoni antigens evaluated in this study stimulated IL-10 production by cells from infected individuals and therefore they have the potential to be used as a modulator of the inflammatory response in asthma.

Merozoite surface protein 2 allelic variation influences the specific antibody response during acute malaria in individuals from a Brazilian endemic area

The antibody response to Plasmodium falciparum parasites of naturally infected population is critical to elucidate the role of polymorphic alleles in malaria. Thus, we evaluated the impact of antigenic diversity of repetitive and family dimorphic domains of the merozoite surface protein 2 (MSP-2) on immune response of 96 individuals living in Peixoto de Azevedo (MT-Brazil), by ELISA using recombinant MSP-2 proteins. The majority of these individuals were carrying FC27-type infections. IgG antibody responses were predominantly directed to FC27 parasites and were correlated to the extension of polymorphism presented by each MSP-2 region. This finding demonstrated the impact of the genetic polymorphism on antibody response and therefore, its importance on malaria vaccine efficacy.

T-cell responses associated with resistance to Leishmania infection in individuals from endemic areas for Leishmania (Viannia) braziliensis

Subclinical or asymptomatic infection is documented in individuals living in endemic areas for leishmaniasis suggesting that the development of an appropriate immune response can control parasite replication and maintain tissue integrity. A low morbidity indicates that intrinsic factors could favor resistance to Leishmania infection. Herein, leishmanial T-cell responses induced in subjects with low susceptibility to leishmaniasis as asymptomatic subjects were compared to those observed in cured cutaneous leishmaniasis (CCL) patients, who controlled the disease after antimonial therapy. All of them have shown maintenance of specific long-term immune responses characterized by expansion of higher proportions of CD4+ as compared to CD8+ Leishmania reactive T-lymphocytes. Asymptomatic subjects had lower indexes of in vitro Leishmania induced lymphoproliferative responses and interferon-gamma (IFN-gamma) production in comparison to CCL patients. On the other hand, interleukin (IL-10) production was much higher in asymptomatics than in CCL, while no differences in IL-5 levels were found. In conclusion, long lived T-cell responses achieved by asymptomatic individuals differed from those who had developed symptomatic leishmaniasis in terms of intensity of lymphocyte activation (proliferation or IFN-gamma) and regulatory mechanisms (IL-10). The absence of the disease in asymptomatics could be explained by their intrinsic ability to create a balance between immunoregulatory (IL-10) and effector cytokines (IFN-gamma), leading to parasite destruction without producing skin tissue damage. The establishment of profiles of cell-mediated immune responses associated with resistance against Leishmania infection is likely to make new inroads into understanding the long-lived immune protection against the disease.

Antiretroviral resistance in individuals presenting therapeutic failure and subtypes of the human immunodeficiency virus type 1 in the Northeast Region of Brazil

This study aimed to analyze human immunodeficiency virus (HIV) mutation profiles related to antiretroviral resistance following therapeutic failure, and the distribution of hiv subtypes in the Northeast Region of Brazil. A total of 576 blood samples from AIDS patients presenting therapeutic failure between 2002 and 2004 were analyzed. The genotyping kit viroSeq® was used to perform viral amplification in order to identify mutations related to hiv pol gene resistance. An index of 91.1% of the patients presented mutations for nucleoside reverse transcriptase inhibitors (nrti), 58.7% for non-nucleoside reverse transcriptase inhibitors (nnrti), and 94.8% for protease inhibitors (pi). The most prevalent mutations were 184V and 215E for nrti, 103N and 190A for nnrti. Most mutations associated with PIs were secondary, but significant frequencies were observed in codons 90 (25.2%), 82 (21.1%), and 30 (16.2%). The resistance index to one class of antiretrovirals was 14%, to two classes of antiretrovirals 61%, and to three classes 18.9%. Subtype B was the most prevalent (82.4%) followed by subtype F (11.8%). The prevalence of mutations related to nrti and nnrti was the same in the two subtypes, but codon analysis related to PI showed a higher frequency of mutations in codon 63 in subtype B and in codon 36 in subtype F. The present study showed that there was a high frequency of primary mutations, which offered resistance to nrti and nnrti. Monitoring patients with treatment failure is an important tool for aiding physicians in rescue therapy.

Comparison of tests for the detection of circulating filarial antigen (Og4C3-ELISA and AD12-ICT) and ultrasound in diagnosis of lymphatic filariasis in individuals with microfilariae

Significant advances were made in the diagnosis of filariasis in the 1990s with the emergence of three new alternative tools: ultrasound and tests to detect circulating antigen using two monoclonal antibodies, Og4C3 and AD12-ICT-card. This study aimed to identify which of these methods is the most sensitive for diagnosis of infection. A total of 256 individuals, all male and carrying microfilariae (1-15,679 MF/mL), diagnosed by nocturnal venous blood samples, were tested by all three techniques. The tests for circulating filarial antigen concurred 100% and correctly identified 246/256 (96.69%) of the positive individuals, while ultrasound detected only 186/256 (73.44%). Of the circulating antigen tests, ICT-card was the most convenient method for identification of Wuchereria bancrofti carriers. It was easy to perform, practical and quick.

Low frequency of human papillomavirus detection in prostate tissue from individuals from Northern Brazil

The presence of human papillomavirus (HPV) was evaluated in 65 samples of prostate tumours and six samples of prostates with benign prostatic hyperplasia from individuals from Northern Brazil. We used a highly sensitive test, the Linear Array HPV Genotyping Test, to detect 37 high and low-risk HPV types. In this study, only 3% of tumour samples showed HPV infection. Our findings support the conclusion that, despite the high incidence of HPV infection in the geographic regions studied, HPV was not associated with a higher risk of prostate cancer. To our knowledge, this is the first study evaluating the frequency of HPV detection in prostatic tissue of individuals from Brazil.

Seroprevalence of HBV, HCV and HIV co-infection in selected individuals from state of São Paulo, Brazil

Few studies are available on hepatitis B virus (HBV), hepatitis C virus (HCV) and human immunodeficiency virus (HIV) co-infection in populations living in small and medium-sized Brazilian cities. We evaluated the seroprevalence of these viruses in selected individuals from a clinic of infectology, who were referred to the University Regional Hospital of the West Region of state of São Paulo, Brazil. Among a total of 7,021 individuals seen in the clinic following receipt of preliminary ELISA results or having the suggested clinical signs of viral hepatitis or HIV, 1,228 were systematically screened. Isolated or associated HBsAg, HCV and HIV antibodies were found in 44.9% of the subjects. Anti-HIV antibodies were found in 24.7% of the patients, 20.3% of whom had an HIV monoinfection and 4.4% of whom were co-infected with hepatitis viruses (HCV: 4%; HBV: 0.4%). Anti-HCV antibodies were found in 14% of the patients and 5.9% had anti-HBsAg antibodies. HCV infection affected males more than females (p < 0.05) and individuals > 50-years old had an increased prevalence of anti-HCV compared to HIV (p = 0.0001) or HBV (p = 0.0063). HCV-RNA was detected in 73.5% of the samples with a predominance of genotype 1 (72.5%). A significant percentage (44.9%) of the selected individuals was positive for antibodies against HBV, HCV and/or HIV; these patients would otherwise have remained undiagnosed.

Peripheral eosinophilia as an indicator of meningitic angiostrongyliasis in exposed individuals

The diagnosis of meningitic angiostrongyliasis (MA) is based on clinical criteria. A lumbar puncture is used as a diagnostic tool, but it is an invasive procedure. The blood eosinophil levels are also assessed and used in the diagnosis of this disease. We enrolled 47 patients with serologically proven MA and 131 controls with intestinal parasite infections. An absolute eosinophil count model was found to be the best marker for MA. An eosinophil count of more than 798 cells led to sensitivity, specificity, positive predictive and negative predictive values of 76.6%, 80.2%, 58.1% and 90.5%, respectively. These data support the use of testing for high blood eosinophil levels as a diagnostic tool for MA in individuals that are at risk for this disease.

Antibodies against the Plasmodium falciparum glutamate-rich protein from naturally exposed individuals living in a Brazilian malaria-endemic area can inhibit in vitro parasite growth

The glutamate-rich protein (GLURP) is an exoantigen expressed in all stages of the Plasmodium falciparum life cycle in humans. Anti-GLURP antibodies can inhibit parasite growth in the presence of monocytes via antibody-dependent cellular inhibition (ADCI), and a major parasite-inhibitory region has been found in the N-terminal R0 region of the protein. Herein, we describe the antiplasmodial activity of anti-GLURP antibodies present in the sera from individuals naturally exposed to malaria in a Brazilian malaria-endemic area. The anti-R0 antibodies showed a potent inhibitory effect on the growth of P. falciparum in vitro, both in the presence (ADCI) and absence (GI) of monocytes. The inhibitory effect on parasite growth was comparable to the effect of IgGs purified from pooled sera from hyperimmune African individuals. Interestingly, in the ADCI test, higher levels of tumour necrosis factor alpha (TNF-α) were observed in the supernatant from cultures with higher parasitemias. Our data suggest that the antibody response induced by GLURP-R0 in naturally exposed individuals may have an important role in controlling parasitemia because these antibodies are able to inhibit the in vitro growth of P. falciparum with or without the cooperation from monocytes. Our results also indicate that TNF-α may not be relevant for the inhibitory effect on P. falciparum in vitro growth.

Prevalence of hepatitis E virus antibodies in individuals exposed to swine in Mato Grosso, Brazil

This study was conducted to estimate the prevalence of hepatitis E antibodies (anti-HEV) among individuals exposed to swine in the rural areas of the state of Mato Grosso (MT) in Brazil. The study included 310 participants who had an average age of 39 years. Fifty-one per cent of the participants were female and 26 (8.4%) were anti-HEV-positive. Concomitantly, we studied 101 blood donors from the urban area of the state capital who had never lived in a rural area or handled swine. Four per cent (4%) of these individuals were anti-HEV-positive (p = 0.206). When we compared the anti-HEV-positive participants who had been exposed to swine with the anti-HEV-negative participants, we noticed associations between the presence of anti-HEV and increased age, a history of blood transfusions and contact with other farm animals. However, after a multivariate analysis was performed, this association was not confirmed. Finally, the ratio of anti-HEV-positive individuals who had been exposed to swine in rural MT was similar to that found in previous studies in Brazil. This prevalence did not characterise this type of exposure as a risk factor for HEV infection in this region.

Primary resistance of HIV to antiretrovirals among individuals recently diagnosed at voluntary counselling and testing centres in the metropolitan region of Recife, Pernambuco

Determining the prevalence and type of antiretroviral (ARV) resistance among ARV-naïve individuals is important to assess the potential responses of these individuals to first-line regimens. The prevalence of primary resistance and the occurrence of recent infections among individuals with human immunodeficiency virus (HIV)/acquired immune deficiency syndrome (AIDS) were identified among recently diagnosed patients at five sexually transmitted disease/AIDS testing and counselling centres in the metropolitan region of Recife (RMR), Pernambuco, Brazil, between 2007-2009. One-hundred and eight samples were analysed using the Calypte® BED assay. Males predominated (56%), as did patients aged 31-50 years. Twenty-three percent presented evidence of a recent HIV infection. The median CD4+ T lymphocyte count was 408 cells/mm³ and the median viral load was 3.683 copies/mL. The prevalence of primary resistance was 4.6% (confidence interval 95% = 1-8.2%) based on criteria that excluded common polymorphisms in accordance with the surveillance drug resistance mutation criteria. The prevalence of resistance to non-nucleoside reverse transcriptase, nucleoside/nucleotide reverse transcriptase and protease inhibitors were 3.8%, 1.5% and 0.8%, respectively. Fifty-seven percent of strains were from clade B, 37.7% were clade F and 3.1% were clade C; there were no statistically significant differences with respect to resistance between clades. Recent infection tended to be more common in men (p = 0.06) and in municipalities in the south of the RMR (Jaboatão dos Guararapes and Cabo de Santo Agostinho) (p = 0.046). The high prevalence of recent infection and the high prevalence of non-B strains in this poor Brazilian region merit further attention.