Update on H5N1 Avian Influenza
by Prof. Hervé Fleury, MD-PhD | Ventum Biotech Scientific Board Member
Birds are the ancestral reservoir of influenza A with a wide variety of subtypes (H1, H2, H3, H4, etc.). Humans are infected with human influenza A viruses; when two A viruses, one avian and the other human, occur in the same animal, they recombine and a new human flu can emerge: for example, the Hong Kong flu in 1968 was the result of a recombination between the Singapore flu of 1957 and a strain of duck influenza virus with the H3 motif. The question that was being asked until 1998 was the possibility of a "pure" avian virus infecting a human. This was confirmed in Hong Kong in 1998 with a child infected with H5N1 bird flu from chickens.
If we focus on H5N1, this virus, which originated in China and Southeast Asia, was transported to Europe by wild birds and then transmitted to domestic birds (refer to our problems of H5N1 infection in ducks in the southwest....); then it reached the American continent and, using the north-south avian air channels, reached Patagonia and South Antarctica. Along the way, the virus was transmitted from wild birds to domestic birds and then to marine mammals (seals) and domestic mammals (pigs, cats, etc.); A few weeks ago, cows were infected in Texas (a farmer was infected from his herd).
Thus, the H5N1 virus is related to humans via domestic birds but also mammals; the possibilities of transmission to humans will increase; cases are described on several continents; They are serious but few because the avian virus has difficulty passing from one human to another. So, what would be the dreaded event? First hypothesis, an adaptation of the H5N1 avian virus to humans with the initiation of a pandemic (this may have happened in 1918); Second hypothesis, recombination in a domestic animal (Cat? Pig? Cow?) of H5N1 with a human H3N2 virus generating a new human strain carrying H5 (H5N2, etc.) and a pandemic because the human virus is adapted for human-to-human transmission.
What are the means of response: first, global monitoring of the circulation of H5N1 (and other important strains such as H7N9); the responsiveness of laboratory tests (molecular techniques such as PCR); the preparation of vaccines against H5N1 and indeed against H5 because antibodies against H5 can neutralize an H5N1 strain; the U.S. has a federal H5N1 vaccine stockpile with cultured and inactivated virus; The company Moderna presented last week in Boston its agenda with the preparation of an H5 mRNA; two companies in Europe have also begun the preparation of a dedicated vaccine. So, we will have tools to fight it; the speed race is underway and let's hope that the emergence of an H5N1 viral pandemic that becomes a plausible hypothesis will not come too soon in our preparation.
