agar and Influenza-in-Birds

Avian Influenza Viruses (AIV) are the causative agents of Avian Influenza (AI), which is a contagious and zoonotic disease in birds. Among birds, wild waterfowls and ducks are the primary and natural reservoirs of low pathogenic avian influenza viruses (LPAI). This study aimed to identify and differentiate between two AIV subtypes (i.e., hemagglutinin and neuraminidase from domestic ducks by hemagglutinin inhibition (HI) and neuraminidase inhibition (NI) assays. To this end, 962 cloacal swabs were collected from domestic ducks being sold at different Iranian Live Bird Markets in Gilan, Mazandaran, and Golestan provinces, located at the southern coast of the Caspian Sea. The samples were inoculated in 10-day-old embryonated specific pathogen-free chicken eggs, and subsequently, harvested allantoic fluids were subjected to agar gel immunodiffusion, HI, and NI assays. In total, five positive samples, including two H4N2 and three H3N2 AIV subtypes were identified. Isolation of H4N2 and H3N2 viruses has never been reported from Iranian domestic ducks previously. This finding further suggests the diversity of LPAI viruses in Iranian ducks and also shows that the HI and NI assays are highly efficient in determining AIV subtypes.

Topics: Agar; Animals; Chickens; Ducks; Hemagglutinins; Influenza A virus; Influenza A Virus, H3N2 Subtype; Influenza in Birds; Iran; Neuraminidase; Phylogeny

We evaluated the utility of 5 commercial enzyme-linked immunosorbent assay (ELISA) kits for detecting antibodies to avian influenza viruses. The sensitivities and specificities of the ELISA kits were compared with those of the agar gel precipitation (AGP) and hemagglutination-inhibition (HI) tests. The results suggest that some ELISA kits might not be suitable for monitoring during the early stages of avian influenza virus infections. Therefore, ELISA kits should only be used in conjunction with a profound knowledge about monitoring of avian influenza.

Topics: Agar; Animals; Antibodies, Viral; Birds; Enzyme-Linked Immunosorbent Assay; Gels; Hemagglutination Inhibition Tests; Influenza A Virus, H5N1 Subtype; Influenza in Birds; Reagent Kits, Diagnostic; Sensitivity and Specificity

The production and supply of reference reagents for the diagnosis of avian influenza (AI) is one of the duties of the World Organization for Animal Health reference laboratories. The lyophilized reagents are routinely shipped on dry ice to both national and international clients. In order to determine the effect of different short-term storage temperatures on the activity of AI reference reagents, vials containing lyophilized avian influenza A antigens and antisera preparations were maintained at 4 C, 22 C, and 37 C over a 21-day period. At days 0, 3, 7, 14, and 21 the reagents were titrated using the hemagglutination test, the hemagglutination inhibition test, or the agar gel immunodiffusion test (AGID). All of the AI antigens that were kept at 4 C and 22 C retained hemagglutinating activity for at least 21 days, but when they were stored at 37 C several lost their hemagglutinating activity. All of the reference antisera tested were still able to inhibit hemagglutination after 21 days, and the antigen used in AGID also gave clear results after 21 days even after incubation at 37 C. Our results therefore indicate that lyophilized avian influenza antigens maintain their hemagglutinating activity at temperatures between 4 C and 22 C for at least 21 days, and both antisera and antigens prepared for AGID remain stable for 21 days between 4 C and 37 C. This information will allow for alternative shipping temperatures than those presently recommended, in addition to the short-term storage of these reagents at nonrefrigerated temperatures.

Topics: Agar; Animals; Antibodies, Viral; Antigens, Viral; Birds; Hemagglutination Inhibition Tests; Hemagglutination Tests; Immunodiffusion; Indicators and Reagents; Influenza in Birds; Temperature; Time Factors