Utilising animal models to evaluate oseltamivir efficacy against influenza A and B viruses with reduced in vitro susceptibility.

The neuraminidase (NA) inhibitor (NAI) oseltamivir (OST) is the most widely used influenza antiviral drug. Several NA amino acid substitutions are reported to reduce viral susceptibility to OST in in vitro assays. However, whether there is a correlation between the level of reduction in susceptibility in vitro and the efficacy of OST against these viruses in vivo is not well understood. In this study, a ferret model was utilised to evaluate OST efficacy against circulating influenza A and B viruses with a range of in vitro generated 50% inhibitory concentrations (IC50) values for OST. OST efficacy against an A(H1N1)pdm09 and an A(H1N1)pdm09 virus with the H275Y substitution in neuraminidase was also tested in the macaque model. The results from this study showed that OST had a significant impact on virological parameters compared to placebo treatment of ferrets infected with wild-type influenza A viruses with normal IC50 values (~1 nM). However, this efficacy was lower against wild-type influenza B and other viruses with higher IC50 values. Differing pathogenicity of the viruses made evaluation of clinical parameters difficult, although some effect of OST in reducing clinical signs was observed with influenza A(H1N1) and A(H1N1)pdm09 (H275Y) viruses. Viral titres in macaques were too low to draw conclusive results. Analysis of the ferret data revealed a correlation between IC50 and OST efficacy in reducing viral shedding but highlighted that the current WHO guidelines/criteria for defining normal, reduced or highly reduced inhibition in influenza B viruses based on in vitro data are not well aligned with the low in vivo OST efficacy observed for both wild-type influenza B viruses and those with reduced OST susceptibility.

Xin-Jia-Xiang-Ru-Yin alleviated H1N1-induced acute lung injury and inhibited the IFN-γ-related regulatory pathway in summer flu.

Seasonal influenza is an acute viral infection caused by influenza virus, which is often prevalent in summer and winter. In contrast to the prevalent focus on winter flu, summer flu is often ignored by epidemiological researchers. However, summer flu should be studied because of the special immune status and the influenza spread mechanism in the hot and humid environment. Moreover, people are more likely to catch a summertime cold upon suddenly entering relatively cool air conditioning from the hot and humid environment. To simulate summer flu, we established a flu animal model under a high temperature and humidity environment during the day with a relatively low temperature at night to investigate the anti-influenza virus effect and mechanism of Xin-Jia-Xiang-Ru-Yin. The results of RT-qPCR verified virus replication, while pathological sections showed inflammation. The expression of the IFN-γ-related regulatory pathway was measured by PCR and immunohistochemistry. We concluded that Xin-Jia-Xiang-Ru-Yin, which combined antiviral therapy and immune modulation effects, might have important therapeutic benefits against summer flu.

[Preclinical studies of live intranasal H5N1 influenza vaccine with the deleted HS1 gene].

The paper gives the results of evaluating the efficiency of deINS1 pandemic H5N1 vaccine candidate VN1203delNS1 which was constructed by reverse genetics on the basis of influenza virus strain A/Vietnam/1203/04. The safety, immunogenicity and cross-protection of the vaccine strain against different H5N1 virus clades were demonstrated in mouse and macaque models. The results showed the possibility of designing a new-generation replication-deficient intranasal influenza vaccine, by applying an approach to deleting the NS1 pathogenicity factor, an antagonist of the interferon system.

Activation of superoxide dismutase in selenium-deficient mice infected with influenza virus.

Selenium (Se) deficiency is associated with decreased activities of Se-dependent antioxidant enzymes, glutathione peroxidase (GPx) and thioredoxin reductase (TR), and with changes in the cellular redox status. We have previously shown that host Se deficiency is responsible for increased virulence of influenza virus in mice due to changes in the viral genome. The present study examines the antioxidant defense systems in the lung and liver of Se-deficient and Se-adequate mice infected with influenza A/Bangkok/1/79. Results show that neither Se status nor infection changed glutathione (GSH) concentration in the lung. Hepatic GSH concentration was lower in Se-deficient mice, but increased significantly day 5 post infection. No significant differences due to Se status or influenza infection were found in catalase activities. As expected, Se deficiency was associated with significant decreases in GPx and TR activities in both lung and liver. GPx activity increased in the lungs and decreased in the liver of Se-adequate mice in response to infection. Both Se deficiency and influenza infection had profound effects on the activity of superoxide dismutase (SOD). The hepatic SOD activity was higher in Se-deficient than Se-adequate mice before infection. However, following influenza infection, hepatic SOD activity in Se-adequate mice gradually increased. Influenza infection was associated with a significant increase of SOD activity in the lungs of Se-deficient, but not Se-adequate mice. The maximum of SOD activity coincided with the peak of pathogenesis in infected lungs. These data suggest that SOD activation in the lung and liver may be a part of a compensatory response to Se deficiency and/or influenza infection. However, SOD activation that leads to increased production of H(2)O(2) may also contribute to pathogenesis and to influenza virus mutation in lungs of Se-deficient mice.

mRNA expression in mouse hypothalamus and basal forebrain during influenza infection: a novel model for sleep regulation.

After influenza infection, C57BL/6J mice develop increased slow-wave sleep (SWS) during the dark phase of the day-night cycle, whereas BALB/cByJ mice develop decreased SWS during the light phase. A previous analysis of CXB recombinant inbred mice revealed a quantitative trait locus (QTL) designated Srilp (sleep response to influenza, light phase) that was related to expression of the BALB/cByJ sleep phenotype. Srilp was localized to the 10- to 12-cM region of mouse Chr 6 between D6Mit74 and D6Mit188. Temt (thioether S-methyltransferase), which is located at region B3 of Chr 6, is a potential candidate gene for Srilp. We evaluated the expression of Temt and other Srilp candidate genes in hypothalamus and basal forebrain of uninfected and influenza-infected C57BL/6J and BALB/cByJ mice. We report here that Temt expression varies significantly with respect to mouse strain, health status, brain region, and day-night phase. C57BL/6J mice show day-night variation in Temt expression in hypothalamus, but BALB/cByJ mice do not. Temt expression in basal forebrain is much higher in C57BL/6J mice than in BALB/cByJ mice. During influenza infection, both C57BL/6J and BALB/cByJ mice show reduced Temt mRNA in basal forebrain at 30 h postinoculation, but expression remains much lower in the BALB/cByJ strain. In contrast, prostaglandin-D-synthase (Ptgds) and lipocalin 2 (Lcn2) mRNA increase in basal forebrain of both strains after influenza infection. Administration of the TEMT inhibitor sinefungin reduces sleep in uninfected BALB/cByJ mice and attenuates influenza-induced sleep enhancement in C57BL/6J mice. These data suggest that strain- and infection-related alterations in sleep may be influenced by Temt expression and perhaps by subsequent effects on prostaglandin metabolism.