Background: In 2005 huge epizooty of H5N1 HPAI occurred in Russia. It had been clear that territory of Russia becoming endemic for H5N1 HPAI. In 2006 several outbreaks have occurred. To develop new vaccines and antiviral therapies, animal models had to be investigated. We choose highly pathogenic strain for these studies.
Cyclamen europaeum tubers extract (CTE) with concentration commonly used for human rhinosinusitis treatment was tested as mucosal adjuvant in experimental intranasal immunization of guinea pigs with concentrated commercially available influenza trivalent vaccine and subsequent infection with influenza strain A/California/04/2009 H1N1pdm. Dual intranasal immunization with vaccine compound consisting of 7.5 µg of each hemagglutinin and 500 µg of CTE in 50 µl induced reciprocal GMT on day 21 after immunization 40 (5-640) against H1N1pdm; 43.20 (5-1280) against H3N2; 10.80 (5-80) against influenza B. Animals with HI titers 1/80 against cell-derived antigen were completely protected against challenge with A/California/04/2009 H1N1pdm09.
The pathogenesis of a disease caused by Qinghai-like H5N1 influenza virus in BALB/c mice was studied. Clinical, morphological, and immunological characteristics of the experimental infection caused by highly pathogenic A/duck/Tuva/01/06/ (H5N1) virus are described.
Neuraminidase (NA) thermostability of influenza A and B viruses isolated from birds, swine and humans was measured to evaluate its variability associated with host body temperature. The highest 50% inactivation temperature (IT 50 ) was observed with H3N8 avian influenza virus (74 °C), and the lowest IT 50 was observed with the seasonal human H3N2 virus (45.5 °C).The IT 50 values of A(H1N1)pdm09 viruses 56.4-58.5 °C were statistically higher than that of the prepandemic strain A/ Solomon Islands/03/06 (52.5 °C). An analysis of Ca 2+ binding sites revealed the correspondence of amino acid changes to NA thermostability. This study demonstrates that changes in NA thermostability correspond to differences in host body temperature.
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