Bioscope ‘09

by  Dr. Barbara Price

          There is nothing like a hot news story to grab our attention and focus on our health. We can use this as an opportunity to see how the system works and improve our understanding of viruses. In ASA reports from 03-6, 04-1, 04-4, 05-2, 07-5, 08-4 and 08-6, we discussed influenza A (H1N1), noting the inclusion of various strains of human H1N1 in seasonal flu vaccines. The global health services have been monitoring H1N1, along with other famous cousins (H5N1 - avian flu), H3N2, H7N2-7 and H9N2. In 08-6, ASA noted that CDC stated their monitoring of H1N1 in 11 states, considerable resistance to Tamiflu (oseltamivir), however, at least four days into global awareness of H1N1, this has not been noted. As many readers also now know, a strain of Influenza A H1N1 was responsible for the 1918 "Spanish Flu".

          Influenzavirus A (genus) is in the Orthomyxoviridae family and the ICTV approved acronym is FLUAV. The virions are made up of an envelope, a matrix protein, a nucleoprotein complex, a nucleocapsid, and a polymerase complex. The virus capsid is enveloped. Virions are generally spherical (80-120 nm diam), but occasionally filamentous (see the Book Review of The Influenza A/H5N1 Atlas on page 4). The virions are densely spiked on the cell surface with the proteins hemagglutinin (HA) and neuraminidase (NA) that project about 10-14 nm (and are 4-6 nm diam.) Each virion has 7 to 8 segments of linear negative-sense single stranded RNA, gene segments.

          The species is Influenza A and the isolate and strain listed on the ICTV is A/PR/8/34 (H1N1), abbreviated FLUAV A/PR/8/34H1N1. A contemporary human H1N1 influenza virus, FLUAV A/Texas/36/91H1N1 was used in a study of the virulence of the 1918 Influenza. There is only one species of Influenzavirus A, which consists of "a cluster of strains that replicate as a continuous lineage" and the genes segments can rearrange with each other and the isolates can also reassort, i.e., exchange their gene segments. Although 15 different HA subtypes and nine different NA subtypes are recognized, these have not been given separate species designations.

          According to the CDC, all work done on clinical samples suspected of containing H1N1 should be in a BSL-2 laboratory, inside a biosafety cabinet. The proper disinfectant is 70% ethanol, 5% Lysol and 10% bleach.

          While the world watched Asia over the last few years, the result of the Hong Kong flu, SARS and H5N1 bird flu, swine flu emerged in Mexico City, the world's tenth largest city. As ASA 09-2 goes to the printer, Mexico has had about 100 deaths, but cases have also been found in Canada, the USA and New Zealand. Although Mexico has closed down public venues in Mexico City, the fear generated by the public health announcements has caused concern around the world.

          A vaccine for swine H1N1 is antigenically different from the human H1N1 and will not work for human H1N1, but as we noted in ASA 03-6: "A vaccine is a back-up protection for when other steps fail." As with other forms of influenza A, normal preventive hygiene is key. Remember "Harry the Hand" from Dr. Brian Davey's 2008 CBMTS presentation.

For the Professional in Government and Industry with an interest in Nuclear, Biological and Chemical Defense, Disarmament and Verification; Emergency and Disaster Medical Planning; Industrial Health and Safety; and Environmental Protection