Elba Regina Sampaio de Lemos

Melioidosis, caused by Burkholderia pseudomallei, is an emerging infectious disease with significant public health implications, historically considered endemic to Southeast Asia and Northern Australia. However, growing evidence highlights its underdiagnosed and underreported status in Brazil, where its true burden remains poorly characterized due to a lack of routine surveillance. This review explores the etiological agent, epidemiology, environmental determinants, clinical manifestations, diagnosis, treatment, and public health impact of melioidosis in Brazil. Reported cases show a strong concentration in the Northeast region, with sporadic cases in the Central-West, Southeast, and North, suggesting a wider distribution than previously recognized. Clinical presentations range from localized cutaneous lesions to fulminant septicemia. The disease is frequently misdiagnosed as tuberculosis, leptospirosis, or other bacterial infections due to non-specific signs and limited laboratory capacity. As climatic changes may lead to bacterial persistence, melioidosis has established itself as an emerging disease that has been expanding geographically in Brazil, requiring improved surveillance, diagnostic capacity, and clinician awareness, along with stronger laboratory infrastructure and access to appropriate antimicrobial therapy.

Hantaviruses, the etiological agents of hemorrhagic fever with renal syndrome (HFRS) and hantavirus pulmonary syndrome (HPS), represent a high-risk zoonotic threat with substantial global health impact. Currently, there is no FDA-approved vaccine. The viral surface glycoprotein (GP) is crucial for host cell entry and is regarded as a key target for vaccine development. However, its variability among hantavirus species limits the effectiveness of conventional vaccine strategies. Epitope-based vaccines offer a promising alternative by enabling the design of broadly protective constructs. In this study, we applied immunoinformatics approaches to design a universal multi-epitope vaccine candidate targeting both HFRS- and HPS-associated hantaviruses through a multi-layered workflow integrating B-cell and T-cell epitope prediction, antigenicity scoring, IFN-γ induction potential, conservation analysis, and population coverage assessment. Viral GPs from SEOV, PUUV, SNV, and ANDV were analyzed using algorithms for B-cell and T-cell epitope prediction. Predicted epitopes were assessed for allergenicity, toxicity, conservation, and population coverage. Two vaccine constructs incorporating β-defensin or 50S ribosomal protein L7/L12 as adjuvants were assessed for physicochemical properties, structural stability and immunogenic potential. Molecular docking analyses provided exploratory ectodomain-compatibility screening, suggesting potential interactions with TLR4 that require future experimental confirmation. The in silico immune simulations suggested potential robust and long-lasting responses with memory cell persistence exceeding one year. Simulations also indicated balanced humoral and cellular responses, robust antibody production, and long-term memory formation suggestive of durable protective immunity. These findings support the rational design of broad-spectrum multi-epitope vaccines against genetically diverse hantaviruses, offering a rational framework for preclinical development of next-generation universal vaccines against hantavirus-associated diseases.

Face masks are widely recognized as a key intervention to limit SARS-CoV-2 transmission, yet the distribution and persistence of viral RNA across different mask regions and layers remain poorly understood. To address this, we analyzed 185 masks collected from 60 SARS-CoV-2-positive individuals in Rio de Janeiro between December 2020 and September 2022. Masks were sectioned into anatomical regions (nose, mouth, sides) and structural layers (inner, middle, outer), and viral RNA was quantified using RT-qPCR. Samples with the highest viral loads were selected for partial sequencing of the spike gene, and paired analyses with swab samples were performed. Statistical comparisons included non-parametric tests and a linear mixed-effects model. Our results showed that the inner layer and nose region consistently harbored the highest viral RNA levels, with no significant differences between surgical and fabric masks. Viral load decreased by an estimated 39% per day, consistent with exponential decay. Sequencing confirmed identical viral genomes in masks and swabs and allowed identification of circulating variants, including Gamma and Omicron. These findings indicate that masks serve not only as effective physical barriers but also as non-invasive sources for genomic surveillance, providing insights into viral shedding patterns and informing strategies for monitoring and controlling SARS-CoV-2 transmission.

The lymphocytic choriomeningitis virus (LCMV) is an under-investigated rodent-borne arenavirus primarily associated with its natural reservoir, the cosmopolitan rodent Mus musculus. Although widely distributed in mice worldwide, human cases are rare, likely under-reported, and often misdiagnosed. While typically asymptomatic or self-limiting, infection can progress to neurological disease, severe congenital outcomes, or fatal illness in transplant recipients. Despite its public health relevance, this study provides the first detection and characterization of LCMV in Brazil. We analyzed 236 rodent serum samples and 78 tissue samples from synanthropic rodents (Mus musculus, Rattus rattus, and Rattus norvegicus) collected during seven independent expeditions across the state of Rio de Janeiro, Southeastern Brazil. Using ELISAs, IgG anti-LCMV antibodies were detected in 20% of rodents, including two R. rattus (2/10), two R. norvegicus (2/95), and forty-five M. musculus (45/131). The LCMV’s RNA was amplified and partially sequenced from fourteen M. musculus, and complete S segment sequences were obtained from two mouse samples. Phylogenetic analyses revealed that these Brazilian strains belong to lineage I, which is composed of strains that induce disease in humans. Our results underscore the importance of implementing integrated surveillance for this zoonosis in Brazil.

Background/Objectives: Understanding the behavior of B cells during infection and vaccination is important for determining protective humoral immunity. We evaluated the profile of humoral immunity and B cell pool in individuals who were acutely infected with SARS-CoV-2, recovered from COVID-19, or received two doses of the AZD1222 vaccine. Methods: Peripheral blood mononuclear cells (PBMCs) from these individuals were subjected to in vitro stimulation to promote the differentiation of B cells into antibody-secreting cells (ASCs), and the ELISpot evaluated the abundance of pan and SARS-CoV-2 Spike S1-reactive IgG+ ASC. Stimulated PBMCs were characterized using flow cytometry. Culture supernatants were assessed for soluble B-cell-activating factors. The IgA and IgG for the S1 were evaluated through ELISA. Results: The recovered individuals displayed a robust S1 ASC compared to acute and vaccinated individuals. Although the frequency of total B cells or B cell subsets did not vary among the groups, plasmablast cells were increased in naïve and double-negative B cells in the acute, recovered, and vaccinated individuals. Similar IgA and IgG production appeared to be present in the acute and recovered individuals. During vaccination, more IgG is produced than IgA. In acute patients, BAFF levels were positively correlated with total B cells and IgG+ plasmablast cells but negatively correlated with IgA+ plasmablast cells. Conclusions: Vaccination and natural infection with COVID-19 induce a differential profile and functionality of B cells. We suggest that new vaccines against COVID-19 incorporate molecular adjuvants that regulate B lymphocyte functionality and consider the beneficial aspects of the IgA response in addition to IgG.

Hantaviruses are zoonotic pathogens associated with severe human diseases such as hemorrhagic fever with renal syndrome and hantavirus pulmonary syndrome. Despite the extensive study of rodent-borne hantaviruses, research on bat-associated hantaviruses remains limited. This study aimed to investigate the seroprevalence and cross-reactivity of neotropical bat samples with rodent- and bat-associated recombinant hantavirus nucleoproteins (rNPs) to improve hantavirus surveillance in the Brazilian Atlantic Forest. The studied bat population consisted of 336 blood samples collected over nearly a decade in five Brazilian states (Bahia, Rio de Janeiro, Santa Catarina, Paraná, and Minas Gerais). Antibodies were detected using IgG ELISA assays with rNPs from bat-borne Mobatvirus xuansonense (XSV) and Loanvirus brunaense (BRNV) and the rodent-borne hantaviruses Orthohantavirus andesense (ANDV) and Orthohantavirus seoulense (SEOV). Results indicated a higher seroprevalence for the BRNV rNP (36.6%) compared to ANDV (7.4%), SEOV (5.7%), and XSV (0.6%). The high sensitivity of the BRNV rNP and the cross-reactivity observed with the ANDV rNP, the main protein used for serological tests in the Americas, indicates that BRNV rNP is a better antigen for the accurate detection of antibodies against hantaviruses in Brazilian bats. These findings underscore the presence of unknown hantaviruses antigenically similar to BRNV in Brazilian bat populations and highlight the urgent need for identifying better antigens for comprehensive hantavirus monitoring in bats.

Background/Objectives: Understanding the behavior of B cells during infection and vaccination is important for determining protective humoral immunity. We evaluated the profile of humoral immunity and B cell pool in individuals who were acutely infected with SARS-CoV-2, recovered from COVID-19, or received two doses of the AZD1222 vaccine. Methods: Peripheral blood mononuclear cells (PBMCs) from these individuals were subjected to in vitro stimulation to promote differentiation of B cells into antibody-secreting cells (ASC), and the ELISpot evaluated the abundance of pan and SARS-CoV-2 Spike S1-reactive IgG+ ASC. Stimulated PBMCs were characterized using flow cytometry. Culture supernatants were assessed for soluble B cell-activating factors. The IgA and IgG for the S1 were evaluated by ELISA. Results: The recovered individuals displayed a robust S1 ASC compared to acute and vaccinated. Although the frequency of total B cells or B-cell subsets did not vary among the groups, plasma cells were increased in naïve and double-negative B cells in the acute, recovered, and vaccinated. Similar IgA and IgG production appeared to be present in the acute and recovered. During vaccination, more IgG is produced than IgA. In acute patients, BAFF levels were positively correlated with total B cells and IgG+ plasma cells, but negatively correlated with IgA+ plasma cells. Conclusions: The vaccination and natural infection with COVID-19 induce a differential profile and functionality of B cells. We suggest that new vaccines against COVID-19 incorporate molecular adjuvants that regulate B lymphocyte functionality and consider the beneficial aspects of the IgA response in addition to IgG.

Rabies, a zoonotic viral disease, poses a significant threat due to its adaptability to diverse environments. Herbivore rabies, predominantly affecting cattle, horses, and goats in Brazil, remains a concern, results in substantial losses in the livestock industry, and poses risks to public health. Rabies virus transmission, primarily through hematophagous bats in Latin America, underscores the need for effective strategies, and vaccination plays a crucial role in controlling herbivorous rabies, with systematic vaccination beingly the primary method. Efforts to control rabies in herbivores include vaccination campaigns, public awareness programs, and the enhancement of surveillance systems. Despite these initiatives, rabies persists and imposes an economic burden and a significant health risk. Economic impacts include losses in the livestock industry, trade restrictions on livestock products, and financial burdens on governments and farmers owing to control measures. Despite the considerable costs of campaigns, surveillance, and control, investing in rabies vaccination and control not only safeguards livestock, but also preserves public health, reduces human cases, and strengthens the sustainability of the livestock industry. Mitigating the impact of herbivorous rabies in Brazil requires integrated approaches and continuous investments in vaccination, surveillance, and control measures to protect public health and ensure the sustainability of the livestock industry, thus contributing to food and economic security.