Retroviral expressed hemagglutinin-neuraminidase protein protects chickens from Newcastle disease virus induced disease.

The hemagglutinin-neuraminidase (HN) gene and the phosphoprotein (P) gene of Newcastle disease virus (NDV) were inserted into a replication competent avian leukosis virus vector. The expression of the HN gene from this vector in chick embryo cells has been previously reported. The P gene is also expressed from this vector in chick embryo cells.

Hemagglutinin mutations related to attenuation and altered cell tropism of a virulent avian influenza A virus.

The H5 hemagglutinin (HA) of a highly virulent avian influenza virus, A/Turkey Ontario/7732/66 (H5N9), was previously shown to have five neutralizing epitopes, and escape mutants within one epitope (group 1) were markedly attenuated (M. Philpott, B. C.

Kidney lesions associated with mortality in chickens inoculated with waterfowl influenza viruses.

Seventy-six type A influenza viruses recovered from waterfowl in Wisconsin, California, South Dakota, Florida, Texas, Alabama, and Nebraska were tested for virulence in chickens. The challenge to chickens was intravenous inoculation of first-, second-, or third-egg-passage virus. Each of the virus strains was tested separately in three or four chickens.

Specific antibody responses and generation of antigenic variants in chickens immunized against a virulent avian influenza virus.

To examine the specificity of the antibody response to the influenza hemagglutinin and the generation of antigenic variants, chickens were immunized against the highly virulent H5 virus A/Ty/Ont/7732/66 (H5N9) and then challenged with a lethal dose of the virus. The antibody responses of these chickens to the hemagglutinin (HA) were examined with an enzyme-linked immunosorbent assay (ELISA) in which their sera were titrated for the ability to block the binding of monoclonal antibodies (MAbs) to five distinct neutralizing epitopes on the viral HA. Based on the ELISA results, a majority (5/6) of the chickens produced antibodies to three of the five neutralizing epitopes on the viral HA.

Antigenic conservation of H1N1 swine influenza viruses.

Influenza viruses of the H1N1 subtype have been continually circulating in pigs in the U.S.A.