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Influenza A viruses of the H2 subtype represent a zoonotic and pandemic threat to humans due to a lack of widespread specific immunity. Although A(H2) viruses that circulate in wild bird reservoirs are distinct from the 1957 pandemic A(H2N2) viruses, there is concern that they could impact animal and public health. There is limited information on AIVs in Latin America, and next to nothing about H2 subtypes in Brazil. In the present study, we report the occurrence and genomic sequences of two influenza A viruses isolated from wild-caught white-rumped sandpipers (Calidris fuscicollis). One virus, identified as A(H2N1), was isolated from a bird captured in Restinga de Jurubatiba National Park (PNRJ, Rio de Janeiro), while the other, identified as A(H2N2), was isolated from a bird captured in Lagoa do Peixe National Park (PNLP, Rio Grande do Sul). DNA sequencing and phylogenetic analysis of the obtained sequences revealed that each virus belonged to distinct subtypes. Furthermore, the phylogenetic analysis indicated that the genomic sequence of the A(H2N1) virus isolated from PNRJ was most closely related to other A(H2N1) viruses isolated from North American birds. On the other hand, the A(H2N2) virus genome recovered from the PNLP-captured bird exhibited a more diverse origin, with some sequences closely related to viruses from Iceland and North America, and others showing similarity to virus sequences recovered from birds in South America. Viral genes of diverse origins were identified in one of the viruses, indicating local reassortment. This suggests that the extreme South of Brazil may serve as an environment conducive to reassortment between avian influenza virus lineages from North and South America, potentially contributing to an increase in overall viral diversity.

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The recently emerged SARS-CoV-2 Omicron sublineages, including the BA.2-derived XBB.1.5 (Kraken), XBB.1.16 (Arcturus), and EG.5.1 (Eris), have accumulated several spike mutations that may increase immune escape, affecting vaccine effectiveness. Older adults are an understudied group at significantly increased risk of severe COVID-19. Here we report the neutralizing activities of 177 sera samples from 59 older adults, aged 62-97 years, 1 and 4 months after vaccination with a 4th dose of ChAdOx1-S (Oxford/AstraZeneca) and 3 months after a 5th dose of Comirnaty Bivalent Original/Omicron BA.4/BA.5 vaccine (Pfizer-BioNTech). The ChAdOx1-S vaccination-induced antibodies neutralized efficiently the ancestral D614G and BA.4/5 variants, but to a much lesser extent the XBB.1.5, XBB.1.16, and EG.5.1 variants. The results showed similar neutralization titers between XBB.1.16 and EG.5.1 and were lower compared to XBB.1.5. Sera from the same individuals boosted with the bivalent mRNA vaccine contained higher neutralizing antibody titers, providing a better cross-protection against Omicron XBB.1.5, XBB.1.16 and EG.5.1 variants. Previous history of infection during the epidemiological waves of BA.1/BA.2 and BA.4/BA.5, poorly enhanced neutralization activity of serum samples against XBBs and EG.5.1 variants. Our data highlight the continued immune evasion of recent Omicron subvariants and support the booster administration of BA.4/5 bivalent vaccine, as a continuous strategy of updating future vaccine booster doses to match newly emerged SARS-CoV-2 variants.

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The raising of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants led to the use of COVID-19 bivalent vaccines, which include antigens of the wild-type (WT) virus, and of the Omicron strain. In this study, we aimed to evaluate the impact of bivalent vaccination on the neutralizing antibody (NAb) response. We enrolled 93 volunteers who had received three or four doses of monovalent vaccines based on the original virus (n = 61), or a booster shot with the bivalent vaccine (n = 32). Serum samples collected from volunteers were subjected to neutralization assays using the WT SARS-CoV-2, and Omicron subvariants. In addition, immunoinformatics to quantify and localize highly conserved NAb epitopes were performed. As main result, we observed that the neutralization titers of samples from individuals vaccinated with the bivalent vaccine were higher for the original virus, in comparison to their capacity of neutralizing the Omicron variant and its subvariants. NAb that recognize epitopes mostly conserved in the WT SARS-CoV-2 were boosted, while those that recognize epitopes mostly present in the Omicron variant, and subvariants were primed. These results indicate that formulation of future vaccines shall consider to target present viruses, and not viruses that no longer circulate.

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INTRODUCTION: The seroprevalence of hepatitis E virus (HEV) in patients with chronic liver disease (CLD) is little known in Brazil. Studies have suggested that HEV may harmfully influence the course of CLD, with a higher risk of progression to cirrhosis. OBJECTIVE: To estimate the prevalence of the anti-HEV antibody (IgG) in patients with CLD and to describe demographic data and risk factors, as well as clinical-laboratory and ultrasound parameters. PATIENTS AND METHODS: Cross-sectional study that included 227 patients with CLD followed at a referral outpatient clinic from June 2022 to March 2023. The patients were investigated clinically and tested for liver functions, anti-HEV IgG and, in positive cases, for HEV-RNA. Ultrasonography of the upper abdomen was also carried out. RESULTS: Investigation of 227 patients (50 with hepatitis B, 49 with nonalcoholic fatty liver disease, 33 with hepatitis C, 17 with alcoholic liver disease, 16 with schistosomiasis and 62 with mixed disease), 55.5% were female, with an average age of 57 ± 13 years; 37.9% had liver cirrhosis. Seven patients (3.08%) presented anti-HEV positive and HEV-RNA negative. Ultrasound identified association between anti-HEV and contact with pigs, presence of gynecomastia or palmar erythema, lower platelet count, higher APRI and FIB-4 values, and splenomegaly. CONCLUSION: Although the prevalence of anti-HEV in patients with CLD was low in this study, the antibody was observed more frequently in cases with a history of contact with pigs and with clinical-laboratory or imaging evidence of more advanced chronic liver disease.

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In Brazil, hepatitis B virus endemicity is low, moderate, or high in some areas, such as Espírito Santo State in the southeast region. In this study, we intend to characterize the basal core promoter (BCP) and pre-core region (PC) variants and their association with clinical/epidemiological disease patterns in patients infected with genotypes A and D. The study included 116 chronic hepatitis B patients from Espírito Santo State, Southeast Brazil, infected with genotypes A and D. Basal core promoter (BCP) and pre-core mutations were analyzed in these patients. The frequency of BCP and PC mutations was compared with age, HBeAg status, HBV genotype and subgenotype, HBV-DNA level, clinical classification, and transmission route. HBeAg-negative status was found in 101 (87.1%) patients: 87 (75.0%) were infected with genotype A (A1 = 85; A2 = 2) and 29 (25.0%) were infected with genotype D (D3 = 24; D4 = 3; D2 = 2). BCP + PC variants altogether were more frequent (48.1%) in genotype D than in genotype A strains (6.0%) (p < 0.001). When this evaluation was performed considering the cases that presented only the A1762T and/or G1764A (BCP) mutations, it was observed that the frequency was higher in genotype A (67.5%) compared to genotype D (7.4%) (p < 0.001). On the other hand, considering the samples with mutations only in positions G1896A and/or G1899A (PC), the frequency was higher in genotype D (75.8%) than in genotype A (6.9%) (p < 0.001). Interestingly, HBV DNA was lower than 2000 IU/mL especially when both BCP/PC mutations were present (p < 0.001) or when only PC mutations were detected (p = 0.047), reinforcing their role in viral replication.

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BACKGROUND: Lung fibrosis is a major concern in severe COVID-19 patients undergoing mechanical ventilation (MV). Lung fibrosis frequency in post-COVID syndrome is highly variable and even if the risk is proportionally small, many patients could be affected. However, there is still no data on lung extracellular matrix (ECM) composition in severe COVID-19 and whether it is different from other aetiologies of ARDS. METHODS: We have quantified different ECM elements and TGF-ß expression in lung tissue of 28 fatal COVID-19 cases and compared to 27 patients that died of other causes of ARDS, divided according to MV duration (up to six days or seven days or more). In COVID-19 cases, ECM elements were correlated with lung transcriptomics and cytokines profile. RESULTS: We observed that COVID-19 cases presented significant increased deposition of collagen, fibronectin, versican, and TGF-ß, and decreased decorin density when compared to non-COVID-19 cases of similar MV duration. TGF-ß was precociously increased in COVID-19 patients with MV duration up to six days. Lung collagen was higher in women with COVID-19, with a transition of upregulated genes related to fibrillogenesis to collagen production and ECM disassembly along the MV course. CONCLUSIONS: Fatal COVID-19 is associated with an early TGF-ß expression lung environment after the MV onset, followed by a disordered ECM assembly. This uncontrolled process resulted in a prominent collagen deposition when compared to other causes of ARDS. Our data provides pathological substrates to better understand the high prevalence of pulmonary abnormalities in patients surviving COVID-19.

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BACKGROUND: Community-Acquired Pneumonia (CAP) is the primary cause of hospitalization in the United States and the third leading cause of death in Brazil. The gold standard for diagnosing the etiology of CAP includes blood culture, Gram-stained sputum, and sputum culture. However, these methods have low sensitivity. No studies investigating the etiology of CAP have been conducted in Brazil in the last 20-years, and the empirical choice of antimicrobials is mainly based on the IDSA guidelines. This is the first national study with this aim, and as a result, there's potential for the Brazilian consensus to be impacted and possibly modify its guidelines rather than adhering strictly to the IDSA's recommendations. METHODS: The aim of this study is to identify the main microorganisms implicated in CAP by employing a multiplex Polymerase Chain Reaction (mPCR) at the foremost public hospital in Brazil. All patients who were admitted to the emergency department and diagnosed with severe CAP underwent an mPCR panel using nasopharyngeal and oropharyngeal swabs, with the aim of detecting 13 bacterial and 21 viral pathogens. RESULTS: A total of 169 patients were enrolled in the study. The mPCR panel identified an etiological agent in 61.5% of patients, with viruses being the most common (42.01%), led by Rhinovirus, followed by Influenza and Coronavirus (non-SARS-CoV-2). Bacterial agents were identified in 34.91% of patients, with S. pneumoniae being the most common, followed by H. influenzae, M. catarrhalis, and S. aureus. Additionally, we found that the prescription for 92.3% of patients could be modified, with most changes involving de-escalation of antibiotics and antiviral therapy. CONCLUSION: Our study revealed different etiological causes of CAP than those suggested by the Brazilian guidelines. Using molecular diagnostic tests, we were able to optimize treatment by using fewer antibiotics.

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BACKGROUND: Since its beginning, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has been a challenge for clinical and molecular diagnostics, because it has been caused by a novel viral agent. Whole-genome sequencing assisted in the characterization and classification of SARS-CoV-2, and it is an essential tool to genomic surveillance aiming to identify potentials hot spots that could impact on vaccine immune response and on virus diagnosis. We describe two cases of failure at the N2 target of the RT-PCR test Xpert® Xpress SARS-CoV-2. METHODS: Total nucleic acid from the Nasopharyngeal (NP) and oropharyngeal (OP) swab samples and cell supernatant isolates were obtained. RNA samples were submitted to random amplification. Raw sequencing data were subjected to sequence quality controls, removal of human contaminants by aligning against the HG19 reference genome, taxonomic identification of other pathogens and genome recovery through assembly and manual curation. RT-PCR test Xpert® Xpress SARS-CoV-2 was used for molecular diagnosis of SARS-CoV-2 infection, samples were tested in duplicates. RESULTS: We identified 27 samples positive for SARS-CoV-2 with a nucleocapsid (N) gene drop out on Cepheid Xpert® Xpress SARS-CoV-2 assay. Sequencing of 2 of 27 samples revealed a single common mutation in the N gene C29197T, potentially involved in the failed detection of N target. CONCLUSIONS: This study highlights the importance of genomic data to update molecular tests and vaccines.

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Cycle threshold (Ct) values in COVID-19 reverse-transcription polymerase chain reaction (RT-PCR) tests estimate the viral load in biological samples. Studies have investigated variables associated with SARS-CoV-2 viral load, aiming to identify factors associated with higher transmissibility. Using the results from tests performed between May/2020-July/2022 obtained from the database of a referent hospital in Sao Paulo, Brazil, we investigated associations between Ct values and patient's age, gender, sample collection setting and pandemic period according to the predominant SARS-CoV-2 variant locally. We also examined variations in Ct values, COVID-19 incidence, mortality, and vaccination coverage over time. The study sample included 42,741 tests. Gender was not significantly associated with Ct values. Age, sample collection setting and the pandemic period were significantly associated with Ct values even after adjustment to the multivariable model. Results showed lower Ct values in older groups, during the Gamma and Delta periods, and in samples collected in emergency units; and higher Ct values in children under 10 years old, home-based tests, during the Omicron period. We found evidence of a linear trend in the association between age and Ct values, with Ct values decreasing as age increases. We found no clear temporal associations between Ct values and local indicators of COVID-19 incidence, mortality, or vaccination between February/2020-November/2022. Our findings suggest that SARS-CoV-2 Ct values, a proxy for viral load and transmissibility, can be influenced by demographic and epidemiological variables.

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OBJECTIVE: To describe and compare the clinical characteristics and outcomes of patients admitted to intensive care units during the first and second waves of the COVID-19 pandemic. METHODS: In this retrospective single-center cohort study, data were retrieved from the Epimed Monitor System; all adult patients admitted to the intensive care unit between March 4, 2020, and October 1, 2021, were included in the study. We compared the clinical characteristics and outcomes of patients admitted to the intensive care unit of a quaternary private hospital in São Paulo, Brazil, during the first (May 1, 2020, to August 31, 2020) and second (March 1, 2021, to June 30, 2021) waves of the COVID-19 pandemic. RESULTS: In total, 1,427 patients with COVID-19 were admitted to the intensive care unit during the first (421 patients) and second (1,006 patients) waves. Compared with the first wave group [median (IQR)], the second wave group was younger [57 (46-70) versus 67 (52-80) years; p<0.001], had a lower SAPS 3 Score [45 (42-52) versus 49 (43-57); p<0.001], lower SOFA Score on intensive care unit admission [3 (1-6) versus 4 (2-6); p=0.018], lower Charlson Comorbidity Index [0 (0-1) versus 1 (0-2); p<0.001], and were less frequently frail (10.4% versus 18.1%; p<0.001). The second wave group used more noninvasive ventilation (81.3% versus 53.4%; p<0.001) and high-flow nasal cannula (63.2% versus 23.0%; p<0.001) during their intensive care unit stay. The intensive care unit (11.3% versus 10.5%; p=0.696) and in-hospital mortality (12.3% versus 12.1%; p=0.998) rates did not differ between both waves. CONCLUSION: In the first and second waves, patients with severe COVID-19 exhibited similar mortality rates and need for invasive organ support, despite the second wave group being younger and less severely ill at the time of intensive care unit admission.

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