Controlling avian flu at the source.

Global agricultural authorities should harmonize with the public-health sector to ensure the exchange of flu virus samples, and establish a single international standard for vaccines, say Robert Webster and Diane Hulse.

Pathogenesis of Hong Kong H5N1 influenza virus NS gene reassortants in mice: the role of cytokines and B- and T-cell responses.

The severity of disease caused in humans by H5N1 influenza viruses remains unexplained. The NS gene of Hong Kong H5N1/97 viruses was shown to contribute to high pathogenicity of reassortants in a pig model. However, the molecular pathogenesis and host immune response underlying this phenomenon remain unclear.

Molecular determinants within the surface proteins involved in the pathogenicity of H5N1 influenza viruses in chickens.

Although it is established that the cleavage site and glycosylation patterns in the hemagglutinin (HA) play important roles in determining the pathogenicity of H5 avian influenza viruses, some viruses exist that are not highly pathogenic despite possessing the known characteristics of high pathogenicity (i.e., their HA contains multiple basic amino acids at the cleavage site and has glycosylation patterns similar to that of the highly pathogenic H5 viruses).

Partial protection against infectious bursal disease virus through DNA-mediated vaccination with the VP2 capsid protein and chicken IL-2 genes.

Several DNA vaccination experiments were performed to determine the protective capability of a plasmid DNA molecule encoding the VP2 capsid protein gene of infectious bursal disease virus (IBDV) injected into chickens in the presence or absence of chicken interleukin 2 (IL-2) plasmid DNA. The results of these experiments indicate that partial protection against IBDV can be achieved by using the VP2 gene of IBDV as a DNA vaccine. Furthermore, the simultaneous injection of chicken IL-2 plasmid DNA significantly increased the protection after challenge with the virulent strain.

Preparation of a standardized, efficacious agricultural H5N3 vaccine by reverse genetics.

Options for the control of emerging and reemerging H5N1 influenza viruses include improvements in biosecurity and the use of inactivated vaccines. Commercially available H5N2 influenza vaccine prevents disease signs and reduces virus load but does not completely prevent virus shedding after challenge with H5N1 virus. By using reverse genetics, we prepared an H5N3 vaccine whose hemagglutinin is 99.