Search

Objective: This study verified the replication efficiency of the Rocio virus in a primary culture of mouse neural cells., Methods: Mixed primary cultures (neurons/glia) obtained from the brains of newborn isogenic BALB/c mice were inoculated with Rocio virus on the 7 th day of culture, and the development of cytopathogenic effects was monitored. The infection was confirmed via immunocytochemistry (anti-ROCV), while viral replication was quantified in infected primary cultures. The titration method used depended on the infection period., Results: Rocio virus efficiently infected primary cultured neural cells, with the highest viral titer causing cytopathic changes was observed at 2 days post infection. The virus-infected primary culture survived for up to 7 days post infection, and viral load quantitation showed viral replication kinetics compatible with the cell death kinetics of cultures., Conclusion: The findings of this study suggest that mouse neural cell primary cultures support Rocio virus replication and could be used as an alternative system for studying Flavivirus infection in the central nervous system.

The World Health Organization has estimated the annual occurrence of approximately 392 million dengue virus (DENV) infections in more than 100 countries where the virus is endemic, which represents a serious threat to humanity. DENV is a serologic group with four distinct serotypes (DENV-1, DENV-2, DENV-3, and DENV-4) belonging to the genus Flavivirus , in the family Flaviviridae . Dengue is the most widespread mosquito-borne disease in the world. The ~10.7 kb DENV genome encodes three structural proteins (capsid (C), pre-membrane (prM), and envelope (E)) and seven non-structural (NS) proteins (NS1, NS2A, NS2B, NS3, NS4A, NS4B, and NS5). The NS1 protein is a membrane-associated dimer and a secreted, lipid-associated hexamer. Dimeric NS1 is found on membranes both in cellular compartments and cell surfaces. Secreted NS1 (sNS1) is often present in patient serum at very high levels, which correlates with severe dengue symptoms. This study was conducted to discover how the NS1 protein, microRNAs-15/16 (miRNAs-15/16), and apoptosis are related during DENV-4 infection in human liver cell lines. Huh 7.5 and HepG2 cells were infected with DENV-4, and miRNAs-15/16, viral load, NS1 protein, and caspases-3/7 were quantified after different durations of infection. This study demonstrated that miRNAs-15/16 were overexpressed during the infection of HepG2 and Huh 7.5 cells with DENV-4 and had a relationship with NS1 protein expression, viral load, and the activity of caspases-3/7, thus making these miRNAs potential injury markers during DENV infection in human hepatocytes.

Between 2016 and 2018, Brazil experienced the largest sylvatic epidemic of yellow fever virus (YFV). Despite to the magnitude and rapid spread of the epidemic, little is known about YFV dispersion. The study evaluated whether the squirrel monkey is a good model for yellow fever (YF) studies. Methods: Ten animals were infected with 1 × 10 6 PFU/mL of YFV, with one negative control. Blood samples were collected daily during the first 7 days and at 10, 20 and 30 days post infection (dpi) for detection of viral load and cytokines by RT-qPCR; measurements of AST, ALT, urea and creatinine were taken; IgM/IgG antibodies were detected by ELISA, and hemagglutination inhibition and neutralization tests were performed. The animals exhibited fever, flushed appearance, vomiting and petechiae, and one animal died. Viremia was detected between 1 and 10 dpi, and IgM/IgG antibodies appeared between 4 and 30 dpi. The levels of AST, ALT and urea increased. The immune responses were characterized by expression of S100 and CD11b cells; endothelial markers (VCAM-1, ICAM-1 and VLA-4), cell death and stress (Lysozyme and iNOS); and pro-inflammatory cytokines (IL-8, TNF-α, and IFN-γ) and anti-inflammatory cytokines (IL-10 and TGF-β). The squirrel monkeys showed changes similar to those described in humans with YF, and are a good experimental model for the study of YF.

Zika virus (ZIKV) is an arbovirus belonging to the genus Flavivirus (Flaviviridae). ZIKV infection is associated with alterations in various organs, including the liver, lungs, and kidneys. Studies on the influence of posttranscriptional control on viral infections have demonstrated that microRNAs (miRNAs) interfere with different stages of the replicative cycle of several viruses and may influence the disease outcome. To shed light on ZIKV-induced regulation of host miRNA-processing machinery in the above organs, we analyzed the expression of genes encoding key proteins of the miRNA pathway in different ZIKV-infected continuous primate cell lineages (HepG2, A549, and MA104) by reverse-transcription quantitative polymerase chain reaction (RT-qPCR). Expression of the genes encoding the miRNA-related proteins DGCR8, Ago1, and Ago3 in HepG2 cells and Drosha, Dicer, Ago2, and Ago3 in A549 and MA104 cells was significantly altered in the presence of ZIKV. Our results suggest that ZIKV modulates miRNA levels during infection in liver, lung, and kidney cells, which may be an additional mechanism of host cell subversion in these organs.