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ABSTRACT Objective The establishment of reference values for a subset of leukocytes is common in clinical practice, and ethnic variations are strongly associated with disease development. In Brazil, indigenous people are vulnerable to infections, and few studies have described the health and disease conditions of this population. This study aimed to provide reference values for immunological cell subsets in indigenous Brazilians living in the state of Mato Grosso do Sul. Methods Flow cytometry and 4-color combinations of monoclonal antibodies were used to characterize cells. A total of 115 healthy adults, mostly females (72%), were included in the study. The results are presented as mean and median (2.5%-97.5% percentiles) for T and B lymphocytes, CD4+ T cells, CD8+ T cells, Natural Killer cells, monocytes, and dendritic cells, providing an average immunological profile for the population in question. Results The relative medians of CD3+, CD4+, and CD8+ T cells were significantly higher in women than in men in a healthy indigenous population. Conclusion To our knowledge, cell reference data from indigenous Brazilians are unknown in the literature. The immune cell results presented in this pioneering study will contribute to the clinical and laboratory evaluation of the Brazilian indigenous population, especially given the important differences when compared with other Brazilian ethnic groups. more...

BackgroundThe COVID-19 pandemic had a major impact on indigenous populations. Understanding the viral dynamics within this population is essential to create targeted protection measures.MethodsA total of 204 SARS-CoV-2 positive samples collected between May 2020 and November 2021 from an indigenous area in Mato Grosso do Sul (MS), Midwestern Brazil, were screened. Samples were submitted to whole genome sequencing using the Nanopore sequencing platform. Clinical, demographic, and phylogenetic data were analyzed.ResultsWe found the co-circulation of six main SARS-CoV-2 lineages in the indigenous population, with the Zeta lineage being the most prevalent (27.66%), followed by B.1.1 (an ancestral strain) (20.21%), Gamma (14.36%) and Delta (13.83%). Other lineages represent 45.74% of the total. Our phylogenetic reconstruction indicates that multiple introduction events of different SARS-CoV-2 lineages occurred in the indigenous villages in MS. The estimated indigenous population mortality rate was 1.47%. Regarding the ethnicity of our cohort, 64.82% belong to the Guarani ethnicity, while 33.16% belong to the Terena ethnicity, with a slightly higher prevalence of males (53.43%) among females. Other ethnicities represent 2.01%. We also observed that almost all patients (89.55%) presented signs and symptoms related to COVID-19, being the most prevalent cough, fever, sore throat, and headache.DiscussionOur results revealed that multiple independent SARS-CoV-2 introduction events had occurred through time, probably due to indigenous mobility, since the villages studied here are close to urban areas in MS. The mortality rate was slightly below of the estimation for the state in the period studied, which we believe could be related to the small number of samples evaluated, the underreporting of cases and deaths among this population, and the inconsistency of secondary data available for this study.ConclusionIn this study, we showed the circulation of multiple SARS-CoV-2 variants in this population, which should be isolated and protected as they belong to the most fragile group due to their socioeconomic and cultural disparities. We reinforce the need for constant genomic surveillance to monitor and prevent the spread of new emerging viruses and to better understand the viral dynamics in these populations, making it possible to direct specific actions. more...

Introduction: Although the adaptive immune responses to the CoronaVac vaccine are known, their dynamics in indigenous communities remain unclear. In this study, we assessed the humoral and cellular immune responses to CoronaVac (Sinovac Biotech Life Sciences, 2021 NCT05225285, Beijing, China), in immunized Brazilian indigenous individuals. Methods: We conducted a prospective cohort study on indigenous Brazilian people between February 2021 and June 2021. Analyses of immune responses were carried out before (T1) and after a vaccination schedule was completed (T2). Demographic data were collected using a questionnaire. Results: We initially included 328 patients; among them, 120 (36.6%) had no SARS-CoV-2 antibodies. Peripheral blood mononuclear cells (PBMCs) were collected from 106 patients during follow-up visits, of which 91 samples were analyzed by immunophenotyping assay to detect SARS-CoV-2-specific memory T-cell response. Post-vaccination, the levels of memory B-cells and Natural Killer T-lymphocytes increased. Bororó village residents, females, and Terena ethnic group members had higher levels of anti-spike IgG antibodies post-vaccination, whereas alcohol and tobacco users had lower concentrations. Conclusions: To our best knowledge, this was the first comprehensive assessment of antibody and T-cell responses against CoronaVac vaccination in indigenous patients. Our findings showed that antibody response and T-cell immunity against SARS-CoV-2 were present in most patients following the vaccination schedule. more...

This study assessed the seroprevalence of SARS-CoV-2 in 496 asymptomatic individuals from Mato Grosso do Sul, located in Dourados, the largest periurban indigenous area in Brazil, from January 25 to February 4, 2021. The volunteers participated before receiving their first dose of the CoronaVac inactivated vaccine. For screening, blood samples were collected and analyzed using SARS-CoV-2 rapid tests and the enzyme-linked immunosorbent assay (ELISA). We observed varying trends in total anti-SARS-CoV-2 antibodies across different variables. Seropositivity among the participants tested was 63.70% (316/496) using the rapid test and 52.82% (262/496) were positive using the ELISA method. The majority of participants identified with the Guarani-Kaiowá ethnic group, with 66.15% (217/328), and other ethnic groups with 58.84% (193/328). The median age of the subjects was 30.5 years, with 79.57% (261/328) being femaleThis research showed the elevated seroprevalence of SARS-CoV-2 antibodies in asymptomatic Brazilians. The findings indicate a high seropositivity rate among the asymptomatic indigenous population of Midwest Brazil. This underscores the overlooked status of these communities and underscores the need for targeted national initiatives that emphasize the protection of vulnerable ethnic groups in the fight against COVID-19. more...

ATLL is a malignant and aggressive leukemia whose survival time is limited. It is known that 5% of individuals infected with HTLV-1, after many years of latency, may develop this disease. The mechanisms by which the evolution of clinical conditions occurs are unknown, and in Brazil there are few studies about ATLL, this some important themes will be addressed in this study. Thus, the objective of this study is to characterize the epidemiological and immunophenotypic profile of patients diagnosed with ATLL, attended at an oncohematological reference center in Salvador, Bahia, in the period between 2010-2018. The methodology consisted of a descriptive, retrospective of time series study, which cases of ATLL were collected from reports belonging a reference laboratory and of medical reports available from Com-HUPES. These data were treated and analyzed statistically, being observed that the majority of cases were female and that a large part have the most aggressive clinical condition Although the literature reports that ATLL clinical condition are always considered as severe, in this study it was observed that patients can achieve long survival in good clinical conditions, according to the treatment administered. In view of the available results, it is possible to conclude that exist a broad distinction between the clinical and molecular forms, being may be an important indicator of the evolution of ATLL. more...

In this study, we investigated the capacity of the recombinant proteins SpaC, NanH, SodC, and PLD of C. pseudotuberculosis to trigger protective humoral and cellular immune responses against experimentally induced C. pseudotuberculosis infection in sheep. The antigens were produced in a heterologous system and were purified by affinity chromatography. Nine sheep were randomly divided into three groups, which were immunized as follows: Group 1 (control)—a mix of adjuvants composed of the inactivated T1 strain of C. pseudotuberculosis and commercial Montanide™ISA 61 VG (T1M); Group 2—rSpaC, rSodC, rPLD, and T1M; Group 3—rNanH, rSodC, rPLD, and T1M. All groups were immunized twice (on days 0 and 30) and challenged on day 90 of the experiment. Humoral and cellular immune responses were evaluated by Enzyme-Linked Immunosorbent Assay (ELISA) to quantify the IgG antibodies and interferon-gamma (IFN-y). Both vaccine formulations with recombinant proteins (groups 2 and 3) could induce a significant humoral IgG immune response in sheep. The proteins rSodC, rPLD, and rNanH were more immunogenic, inducing significant levels of IgG antibodies after the first dose of the vaccine or after the challenge, maintaining constant levels until the end of the experiment. However, it was not possible to differentiate between the cellular responses induced by the vaccines. This lack of effectiveness points toward the need for further studies to improve the efficacy of this subunit-based vaccine approach. more...

Use of CCR5 antagonists requires previous viral tropism determination. The available methods have high cost, are time-consuming, or require highly trained personnel, and sophisticated equipment. We compared a flow cytometry-based tropism assay with geno2pheno method to determine HIV-1 tropism in AIDS patients, in Bahia, Brazil. We tested peripheral blood mononuclear cells of 102 AIDS patients under antiretroviral therapy by using a cytometry-based tropism assay and geno2pheno assay. Cellular membrane receptors were identified by using CXCR4, CCR5 and CD4 monoclonal antibodies, while detection of cytoplasmic mRNAs for gag and pol HIV regions was achieved by using a labeled probe. Genotypic identification of X4 and R5 tropic viruses was attempted by geno2pheno algorithm. There was a high degree of concordance between cytometry-based tropism assay and geno2pheno algorithm in determination of HIV-1 tropism. Cytometry-based tropism assay demonstrated higher sensitivity and specificity in comparison to geno2pheno, which was used as a gold-standard. One sample could not be amplified by geno2pheno method, but was classified as duotropic by cytometry-based tropism assay. We did not find any association between CD4+ count or plasma HIV-1 RNA viral load and tropism results. The overall performances of cytometry-based tropism assay and geno2pheno assay were almost identical in determination of HIV-1 tropism. Keywords: HIV-1, Tropism, Flow cytometry, Geno2pheno more...

This study evaluated total lymphocyte count (TLC) as a substitute marker for CD4+ cell counts to identify patients who need prophylaxis against opportunistic infection (CD4 < 200 cells/mm³) and patients with CD4 < 350 cells/mm³ (Brazilian threshold value of CD4 count to define AIDS). We evaluated TLC and CD4+ cells count of 1,174 HIV-infected patients, in Salvador, Brazil, from May 2003 to September 2004. CD4+ cell counts were performed by flow cytometry, and TLC was measured with an automated hematological counter. The mean CD4 count was 430 cells/mm³ (range: 4 to 2,531 cells/mm³). Mean TLC was 1,900 cells/mm³ (range: 300 to 6,200 cells/mm³). Using a threshold value of 1,000 cells/mm³ for TLC, the positive predictive value (PPV) was 77% for CD4 < 200 cells/mm³, but the sensitivity was only 29%, while the negative predictive value (NPV) was 88%, with 98% specificity. Similar findings were observed for CD4 count < 350. Using the same threshold value of 1,000 cells/mm³ for TLC, sensitivity was 14%, and specificity 99% (PPV= 94%; NPV=62%). In 70/1,510 (5%) of the samples the sum of CD4 and CD8 cell counts was greater than the TLC and in 27% (419/1,510) this sum was below 65% of the TLC. TLC has a high specificity to identify patients for prophylaxis, but a quite low sensitivity. It is not useful as an alternative to CD4+ T-cell counts as a marker in HIV-infected patients. more...

SUMMARY In Brazil, the existing reference values for T-lymphocytes subsets are based on data originated in other countries. There is no local information on normal variation for these parameters in Brazilian adults and children. We evaluated the normal variation found in blood donors from five large Brazilian cities, in different regions, and in children living in Salvador, and Rio de Janeiro. All samples were processed by flow cytometry. The results were analyzed according to region, gender, and lifestyle of blood donors. A total of 641 adults (63% males), and 280 children (58% males) were involved in the study. The absolute CD3+, and CD4+ cells count were significantly higher for females (adults and children). Higher CD4+ cell count in adults was associated with smoking, while higher CD8+ count was found among female children. Higher counts, for all T-cells subsets, were detected in blood donors from southeast / south regions while those living in the northern region had the lowest values. Individuals from midwestern and northeastern regions had an intermediate count for all these cells subsets. However, these differences did not reach statistical significance. In Brazil, gender and smoking, were the main determinants of differences in T-lymphocytes reference values. more...

Acute HIV infection is rarely recognized as the signs and symptoms are normally unspecific and can persist for days or weeks. The normal HIV course is characterized by a progressive loss of CD4+ cells, which normally leads to severe immunodeficiency after a variable time interval. The mean time from initial infection to development of clinical AIDS is approximately 8-10 years, but it is variable among individuals and depends on a complex interaction between virus and host. Here we describe an extraordinary case of a man who developed Pneumocisits jiroveci pneumonia within one month after sexual exposure to HIV-1, and then presented with 3 consecutive CD4 counts bellow 200 cells/mm3 within 3 months, with no other opportunistic disease. Although antiretroviral therapy (AZT+3TC+ATZ/r) was started, with full adherence of the patient, and genotyping indicating no primary antiretroviral resistance mutations, he required more than six months to have a CD4 restoration to levels above 200 cells/mm3 and 10 months to HIV-RNA to become undetectable. Keywords: HIV, acute infection, progression, AIDS more...

Acute HIV infection is rarely recognized as the signs and symptoms are normally unspecific and can persist for days or weeks. The normal HIV course is characterized by a progressive loss of CD4+ cells, which normally leads to severe immunodeficiency after a variable time interval. The mean time from initial infection to development of clinical AIDS is approximately 8-10 years, but it is variable among individuals and depends on a complex interaction between virus and host. Here we describe an extraordinary case of a man who developed Pneumocisits jiroveci pneumonia within one month after sexual exposure to HIV-1, and then presented with 3 consecutive CD4 counts bellow 200 cells/mm³ within 3 months, with no other opportunistic disease. Although antiretroviral therapy (AZT+3TC+ATZ/r) was started, with full adherence of the patient, and genotyping indicating no primary antiretroviral resistance mutations, he required more than six months to have a CD4 restoration to levels above 200 cells/mm³ and 10 months to HIV-RNA to become undetectable. more...