NIAID Labs Meet the H1N1 Challenge
The 2009 outbreak of a new strain of H1N1 influenza A demonstrates that continuing vigilance, planning, and strong public health research capability are essential defenses against emerging health threats. Research on H5N1 (bird flu) and other influenza viruses with pandemic potential has prepared NIAID scientists to respond to this newest influenza threat. They have expanded and refocused projects to include studies of the course of the virus, the origin of the virus, H1N1-infected patients, and a preventive vaccine. Many of these studies involve collaborations with other federal agencies, academia, and the private sector.
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Colorized negative stained transmission electron micrograph depicting the 2009 H1N1 influenza virus
Credit: CDC |
Characterizing 2009 H1N1 Virus
To better understand how potential pandemic influenza viruses, such as the avian H5N1 virus, cause severe disease in humans, scientists in NIAID labs previously developed several animal models to study the course of the disease. Working in collaboration with the CDC, which shared with NIAID samples of the new H1N1 strain for research purposes, NIAID scientists are now using these models to study H1N1.
Animal models such as mice, ferrets, and nonhuman primates allow scientists to compare the new H1N1, classical swine H1N1, and European swine H1N1 with other influenza strains, such as avian viruses and seasonal influenza strains. Specifically, scientists will study how the virus replicates, what kind of pathologic changes the infection produces, and how easily the virus is transmitted. Scientists also will use a recently established x-ray imaging system to determine whether the new H1N1 virus affects the lower respiratory tract, as influenza infections that do are typically more severe than those in the upper respiratory system.
Ultimately, this information will help scientists understand how this emerging virus causes severe disease and may help them develop a vaccine or new antiviral therapy to prevent or treat it. Scientists will also evaluate how well immunity to current and past strains of human and swine influenza protects against the new H1N1 virus.
Determining Where the Virus Came From
NIAID scientists recently published a study of swine influenza virus evolution, comparing classical swine H1N1 viruses with European avian-like H1N1 viruses. Because the newly emerging H1N1 virus descended from both of these lineages, the study’s authors will expand their work and conduct similar analyses of the gene sequences of the novel H1N1 virus. Such detailed studies of the virus’s evolution will provide scientists with clues about the path and timing of host adaptation, as well as clues about which viral genes are associated with virulence.
Studying Influenza Sufferers
NIAID is amending an established influenza research protocol at the NIH Clinical Center to allow enrollment of patients found to have the newly emerging H1N1 strain. Patients will receive the best available care while scientists conduct a careful study of their clinical history, measure the amount of virus in respiratory secretions, and evaluate various elements of the body’s immune response to infection.
Developing Vaccines
NIAID scientists also are collaborating with MedImmune, the manufacturer of the FluMist nasal spray influenza vaccine, to prepare to develop a vaccine against the newly emerging H1N1 virus. This collaboration is an expansion of ongoing work to develop live, attenuated vaccines against other influenza strains, such as H5N1, H7N3, and H2N2. Live, attenuated vaccines contain a version of the living microbe that has been weakened in the lab so it can’t cause disease. Because a live, attenuated vaccine is the closest thing to a natural infection, these vaccines can elicit strong cellular and antibody responses.
For a potential vaccine against the newly emerging H1N1, MedImmune will generate a “seed virus,” which will be used to grow larger amounts of virus for vaccine studies. NIAID scientists will perform studies in mice and ferrets to determine whether the vaccine candidate is weak enough to not cause disease, strong enough to stimulate the immune system, and efficient enough to protect against the H1N1 virus. Clinical trials are planned to determine age-specific immune responses and whether certain age groups have pre-existing antibodies that might interact with the vaccine virus.
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