In vivo and in vitro antiviral effects of berberine on influenza virus.

OBJECTIVE

To explore the potential effects of berberine on influenza virus infection both in vitro and in vivo.

METHODS

In vitro anti-influenza virus assays were performed by cytopathogenic effect and neuraminidase assays in Madin Darby canine kidney cells. In vivo anti-influenza virus assays were performed on the viral pneumonia model of mice. The numbers of mice that died within day 2 to day 14 postinfection were recorded to calculate the mortality. On days 2, 4, and 6, the viral titers in the lungs were determined by hemagglutination assay; hematoxylin/eosin staining was used to assess the pathogenic changes of lung tissues; the concentrations of tumor necrosis factor-alpha (TNF-α) and monocyte specific chemoattractant molecule (MCP-1) were measured by radio immunoassay or enzyme-linked immunosorbent assay; the concentrations of nitric oxide (NO) and inducible nitric oxide synthetase (iNOS) were detected by colorimetric method; reverse transcription polymerase chain reaction was used to detect the mRNA level of TNF-α and MCP-1.

RESULTS

Berberine showed inhibitory effects on cytopathogenic effects and neuraminidase activity of virus, with the therapeutic index 9.69. In vivo, berberine decreased mice mortality from 90% to 55%, reduced virus titers in the lungs on day 2 postinfection (P<0.05). The lung histology scores were 1.50 ± 0.67, 4.50 ± 1.00, and 5.50 ± 1.00 in the berberine group on days 2, 4, and 6, respectively, which were significantly reduced compared to 2.17 ± 0.22, 6.83 ± 0.44, and 8.50 ± 0.33 in the infected group (P<0.05). The productions of NO and iNOS were repressed by berberine compared with those in the infected group (P<0.01). The transcription and expression of TNF-α were inhibited by berberine on day 4 (P<0.01) and day 6 (P<0.05), and those of MCP-1 were inhibited on day 6 (P<0.01) compared with the infected group.

CONCLUSIONS

Berberine exhibited antiviral effects on the influenza virus both in vitro and in vivo. The possible therapeutic mechanism of berberine on influenza-induced viral pneumonia might be inhibiting the virus infection, as well as improving the pathogenic changes by repressing inflammatory substances release.