Acta virologica最新文献

Standard assays based on ELISA and RT-PCR have been widely used to detect flaviviral infections, including the Zika virus (Zika). Despite their simple, unique, and sensitive features, RT-PCR and ELISA-based assays cannot meet the requirements of high-throughput screening of bulk samples during an outbreak. Several research groups around the world are working on the development of rapid, multiplex, and sensitive assays to overcome the limitations of standard assays used in viral detection. Recent advances in flow cytometry have led to remarkable progress in its use as a basic analysis tool in laboratories. Here, we used the advantages of flow cytometry to develop a Zika detection assay using recombinant Zika envelope (E) protein. The E protein-based flow cytometry assay was able to detect anti-Zika E antibodies from Zika-infected patients, Zika-infected mice, and mice immunized with recombinant Zika E protein. We report the development of the first flow cytometry-based diagnostic assay that can be used for Zika detection. Its rapid turnaround time and ability to detect antibodies from Zika-infected patients can be used to improve the diagnostic accuracy of Zika detection. Keywords: Flavivirus; Zika virus; E protein; NS-1 protein; flow cytometry; ELISA; RT-PCR.

Oseltamivir phosphate (OS) is currently the most frequently used influenza antiviral drug. It moderates the course of influenza virus type A (IAV) infection, however, its impact on the induction of virus-neutralizing antibodies (VNAbs) is not understood in details. Here, we examined the influence of low (10 mg/kg) or high (60 mg/kg) doses of OS on the viral titer in lungs of BALB/c mice infected with 0.5 LD50 of IAV and on the level of VNAbs. Prophylactic application of OS (6 h before the infection) delayed the increase of viral titer in lungs with a lower peak in comparison to non-treated control mice. After therapeutic OS application (44 h after the infection), maximum of virus titer did not significantly change. However, the induction of VNAbs strongly decreased, to 16.7%-18.1% of the control, after preventive application of high OS dose. A minimal decrease of VNAbs titers was observed in groups of mice treated with low dose of OS applied therapeutically. They lowered to 91.1% / 14 or to 94.1% / 21 days post infection (p.i.) of VNAbs titers of non-treated control mice. In all other groups, levels of VNAbs titers dropped to 26.5-53.7% of those of non-treated mice. It should be noted that VNAbs titers were in direct proportion to maximal virus titers in mouse lungs of corresponding groups. In summary, after OS application the clinical symptoms of the disease were milder or non-observable in all OS-treated groups, but the lowering of VNAbs titers was dependent on the OS dose and interval between drug app-lication and the start of infection. Keywords: influenza A virus; Oseltamivir; prophylactic treatment; therapeutic treatment; virus-neutralizing antibodies.

Rotavirus is the most important etiological agent of infectious diarrhea in children under 5 years of age with more than 125,000 deaths occurring annually worldwide. The present study aims to determine the effect of curcumin, a natural polyphenol compound, on rotavirus in a cell culture model. The anti-viral activity of curcumin was evaluated by reverse-transcriptase quantitative PCR (RT-qPCR), TCID50, and western blot techniques to assess CC50 in curcumin-treated MA104 cells as well as EC50 and SI within the infected MA104 cell line. Our findings supported that curcumin exerted an inhibitory influence against rotavirus in a dose-dependent manner and decreased the viral titer and VP6 expression by ~99% at a concentration of 30 μM (p Keywords: curcumin; rotavirus; RT-qPCR; in vitro; anti-rotavirus agent.

Presence of alternate hosts of plants is a great threat to the agriculture industry. Plants from several species growing in the papaya orchards affected by papaya sticky disease were examined for Papaya meleira virus (PMeV) infection causing this disease. The viral dsRNA was already detected in some plants from the family Poaceae or in watermelon. To identify new hosts of PMeV, we have collected 38 plant species belonging to 15 families of common weed species found in papaya-growing areas in México and used reverse-transcription PCR (RT-PCR) or quantitative real-time RT-PCR (RT-qPCR) for virus detection. We have detected the viral RNA in 11 species belonging to the families Acanthaceae, Fabaceae and Poaceae. Under experimental conditions, PMeV-Mx in Panicum hirsutum and Ruellia nudiflora inoculated weed species, showed that PMeV-Mx is able to replicate in plant cells of these species and spread in a systemic way. These results highlight the importance of weed species as potential virus reservoirs for PMeV-Mx Keywords: Papaya meleira virus; papaya sticky disease; Carica papaya; RT-PCR; TaqMan.

Vaccination is one of the basic strategies in the fight against foot-and-mouth disease (FMD) in endemic regions. Today, commercially available FMD vaccines are prepared with inactive whole virion, which has low immunogenicity. Therefore, considerable effort has been devoted to finding novel adjuvants. Although mineral oils are among the most common adjuvants, it is still difficult to provide a long-term and robust immune response. Combined adjuvant systems are currently being studied to solve the problem. Saponins and CpG-ODNs have been shown to increase the immune response to vaccines individually in various studies. In this study, the effect of different adjuvants and their combinations (Quil-A, E. coli DNA, and MontanideTM ISA 206) on total and neutralizing antibody response in sheep was investigated. According to the results, the Quil-A group induced the highest antibody level, followed by the combination of Quil-A and the E. coli DNA group. The group containing E. coli DNA also caused a higher antibody response than the group containing only MontanideTM ISA 206 for certain days of sampling. These affordable alternatives of saponin and CpG sources can be used individually to increase the potency of the FMD vaccine for mass vaccinations of sheep. Keywords: foot-and-mouth disease; vaccine; adjuvant; Quil-A; E. coli DNA; combination of adjuvants.

Defensins, crucial components of the innate immune system, play a vital role against infection as part of frontline immunity. Association of SARS-CoV-2 infection with defensins has not been investigated. In this study, we have investigated the expression of defensin genes in the buccal cavity from patients with COVID-19 infection along with negative control samples. Nasopharyngeal/oropharyngeal swab samples collected for screening SARS-CoV-2 infection in early 2020 from Hyderabad, India, were analyzed for the expression of major defensin genes by the quantitative real-time reverse transcription polymerase chain reaction, qRT-PCR. Forty SARS-CoV-2 infected positive and 40 negative swab samples were selected for this study. Based on the qRT-PCR analysis involving gene specific primers for defensin genes, 9 defensin genes were found to be expressed in the nasopharyngeal/oropharyngeal cavity. Four defensin genes were found to be significantly down regulated in SARS-CoV-2 infected patients in comparison with the control samples based on differential expression analysis. The significantly down regulated genes were defensin beta 4A/B, 106B, 107B, and 103A. Down regulation of human beta defensin 2, 3, 6 and 7 suggests that antiviral innate immune response provided by defensins may be compromised in SARS-CoV-2 infection resulting in progression of the disease. Correction of the down regulation process through appropriate defensin peptide-based therapy could be an attractive method of treatment. Keywords: host defense; defensins; COVID-19; gene regulation; SARS-CoV-2.

Interferons (IFNs) mediate innate antiviral activity against many types of viruses, including influenza viruses. In light of their potential use as anti-influenza agents, we examined whether resistance to these host antiviral proteins can develop. We generated IFN-β-resistant variants of the A/California/04/09 (H1N1) virus by serial passage in a human airway epithelial cell line, Calu-3, under IFN-β selective pressure. The combination of specific mutations (i.e., L373I in PB1, K154E1, D222G1, I56V2, and V122I2 in HA, and M269I in NA) correlated with decreased ability of the virus to induce expression of IFN (IFNB1, IFNL1, and IFNL2/3) and IFN-stimulated genes (IFIT1, IFIT3, OAS1, IRF7, and MX1) by target respiratory epithelial cells. In addition, the IFN-induced mutations were associated with decreased HA binding affinity to α2,6 sialyl receptors, reduced NA enzyme catalytic activity, and decreased polymerase transcription activity. Our findings demonstrate that the mutations in the influenza HA, NA, and PB1 proteins induced by IFN-b selective pressure significantly increase viral ability to productively infect and replicate in host cells. Keywords: influenza A virus; interferon-β; lung epithelial cells; interferon response.