Neuraminidase (NA) of influenza A (H3N2) viruses was characterized after purification by gel filtration and proteolytic treatment, using the X-31 variant strain that is a reassortment between the influenza A/Victoria/3/75 (responsible for the 1975 pandemic) and the influenza A/PR/8/34 virus samples, as a model. In the purification process, NA heads, that is the spike responsible for the virus sialidase activity, were purified by filtration through a Bio-Gel polyacrylamide column. The enzyme activity was determined by periodic acid/thiobarbituric acid assay and high-performance thin-layer chromatography. The sialidase showed preference for the α-2,3-linkage over the α-2,6-linkage of sialyllactoses (K_m of 1.8 and 5.2 × 10^–4M, respectively) at pH 5.2. The enzyme acted on natural and synthetic substrates at different hydrolysis rates, as well as on human erythrocytes (A group, Rh+) and yeast (Candida albicans) cells. The active NA produced by gel filtration was characterized by different parameters of its sialidase activity, also showing to be a suitable tool for the identification of natural sialocompounds and for the screening of antisialidase drugs to treat influenza virus infections.

Zika virus (ZIKV) was first discovered in 1947 in Uganda but was not considered a public health threat until 2007 when it found to be the source of epidemic activity in Asia. Epidemic activity spread to Brazil in 2014 and continued to spread throughout the tropical and subtropical regions of the Americas. Despite ZIKV being zoonotic in origin, information about transmission, or even exposure of non-human vertebrates and mosquitoes to ZIKV in the Americas, is lacking. Accordingly, from February 2017 to March 2018, we sought evidence of sylvatic ZIKV transmission by sampling whole blood from approximately 2000 domestic and wild vertebrates of over 100 species in West-Central Brazil within the active human ZIKV transmission area. In addition, we collected over 24,300 mosquitoes of at least 17 genera and 62 species. We screened whole blood samples and mosquito pools for ZIKV RNA using pan-flavivirus primers in a real-time reverse-transcription polymerase chain reaction (RT-PCR) in a SYBR Green platform. Positives were confirmed using ZIKV-specific envelope gene real-time RT-PCR and nucleotide sequencing. Of the 2068 vertebrates tested, none were ZIKV positive. Of the 23,315 non-engorged mosquitoes consolidated into 1503 pools tested, 22 (1.5%) with full data available showed some degree of homology to insect-specific flaviviruses. To identify previous exposure to ZIKV, 1498 plasma samples representing 62 species of domestic and sylvatic vertebrates were tested for ZIKV-neutralizing antibodies by plaque reduction neutralization test (PRNT₉₀). From these, 23 (1.5%) of seven species were seropositive for ZIKV and negative for dengue virus serotype 2, yellow fever virus, and West Nile virus, suggesting potential monotypic reaction for ZIKV. Results presented here suggest no active transmission of ZIKV in non-human vertebrate populations or in alternative vector candidates, but suggest that vertebrates around human populations have indeed been exposed to ZIKV in West-Central Brazil.

Background: The hepatitis B virus (HBV) is one of the leading causes of acute, chronic and occult hepatitis (OBI) representing a serious public health threat. Cytokines are known to be important chemical mediators that regulate the differentiation, proliferation and function of immune cells. Accumulating evidence indicate that the inadequate immune responses are responsible for HBV persistency. The aim of this study were to investigate the cytokines IFN-γ, TNF-α, IL-2, IL-4, IL-6, IL-10 and IL-17A in patients with OBI and verify if there is an association between the levels of these cytokines with the determination of clinical courses during HBV occult infection.Methods: 114 patients with chronic hepatitis C were investigated through serological and molecular tests, the OBI coinfected patients were subjected to the test for cytokines using the commercial human CBA kit. As controls, ten healthy donors with no history of liver disease and 10 chronic HBV monoinfected patients of similar age to OBI patients were selected.Results: Among 114 HCV patients investigated, 11 individuals had occult hepatitis B. The levels of cytokines were heterogeneous between the groups, most of the cytokines showed higher levels of production detection among OBI/HCV individuals when compared to control group and HBV monoinfected pacients. We found a high level of IL-17A in the HBV monoinfected group, high levels of TNF-α, IL-10, IL-6, IL-4 and IL-2 in OBI/HCV patients.Conclusion: These cytokines could be involved in the persistence of HBV DNA in hepatocytes triggers a constant immune response, inducing continuous liver inflammation, which can accelerate liver damage and favor the development of liver cirrhosis in other chronic liver diseases.

Hepatocellular carcinoma (HCC) is the most common primary liver malignancy and a leading cause of cancer-related mortality worldwide. Genetic alterations play a critical role in hepatocarcinogenesis, with mutations in the telomerase reverse transcriptase promoter (TERTp) and CTNNB1 exon 3 representing two of the most frequently reported somatic events in HCC. However, the frequency and distribution of these mutations vary across geographic regions and viral etiologies, particularly hepatitis B virus (HBV) and hepatitis C virus (HCV). This study aimed to assess the global distribution and etiological associations of TERTp and CTNNB1 exon 3 mutations in HCC through a comprehensive literature review. Our analysis, encompassing over 4000 HCC cases, revealed that TERTp mutations were present in 49.2% of tumors, with C228T being the predominant variant (93.3% among mutated cases). A striking contrast was observed between viral etiologies: TERTp mutations were detected in 31.6% of HBV-related HCCs, compared to 66.2% in HCV-related cases. CTNNB1 exon 3 mutations were identified in 23.1% of HCCs, showing a similar association with viral etiology, being more common in HCV-related cases (30.7%) than in HBV-related tumors (12.8%). Geographically, both mutations exhibited comparable patterns, with higher frequencies in Europe, Japan, and the USA, while lower rates were observed in China, Taiwan, and South Korea. Our findings underscore the distinct molecular profiles of HCC according to viral etiology and geographic origin, highlighting the need for region- and etiology-specific approaches to HCC prevention, diagnosis, and targeted therapy.