After endless debates and controversies on whether two studies that demonstrated how bird flu, also known as avian H5N1 influenza, or avian flu, should be published, one of them has appeared in the latest issue of the journal Nature in its entirety. The two studies aimed for publication in journals Nature and Science show how the bird flu virus could become transmissible from mammal-to-mammal; as humans are mammals, the same would apply to humans.
Experts had speculated that this knowledge could be dangerous in the hands of bioterrorists.
University of Wisconsin-Madison flu researcher, Yoshihiro Kawaoka, whose study of H5N1 virus transmissibility was at the center of the controversy, said, “Our study shows that relatively few amino acid mutations are sufficient for a virus with an avian H5 hemagglutinin to acquire the ability to transmit in mammals. This study has significant public health benefits and contributes to our understanding of this important pathogen…By identifying mutations that facilitate transmission among mammals, those whose job it is to monitor viruses circulating in nature can look for these mutations so measures can be taken to effectively protect human health.”
Other mutations we do not know about which might make the virus mammal-transmissible may be possible, Kawaoka cautions. It is because of this that further research into additional potential mutations are important.
In this latest Nature article, the Wisconsin scientists describe a bird flu/human flu hybrid virus that was modified in the lab; the virus has the capacity to become transmissible in an animal model for human infection with just a few mutations.
Ferrets were used in the new study, because these animals generate small droplets when they are infected with flu and sneeze and cough - the droplets carry the virus from animal-to-animal, demonstrating transmissibility. There are many cellular similarities between the ferret's and human's respiratory tract.
At least 600 humans have been infected with the H5N1 viruses since 2003. The majority of infections have occurred in Asia. Over 50% of infected people did not survive. Humans can become infected after close contact with poultry. However, an infected human extremely rarely can infect another human - this fact has led many scientists and health experts to believe that H5N1, although deadly, is not really a pandemic threat.
The NIAID (United States National Institute of Allergy and Infectious Disease), in a Blue Ribbon Panel report (2006) decided that research on virus transmission from animal reservoirs should be a priority. The World Health Organization (WHO) came to the same conclusion in its 2009 Public Health Research Agenda.
Kawaoka's study results demonstrated that the experimental mutant virus could be controlled with current medical countermeasures. The H5N1 vaccine proved effective, as well as the antiviral oseltamivir (Tamiflu).
The NSABB (National Science Advisory Board for Biosecurity), which advises the NIH (National Institutes of Health), last year recommended removing sensitive data from Kawaoka laboratory's report. The panel recommended that the same be done with a Dutch study. The Panel wanted the methodologies used to make the virus transmissible removed from the report, as well as the mutations required to make the virus mammal-transmissible. But the World Health Organization recommended that the two studies be published in their full form. By April, the U.S. government reversed its position with new information and revisions. The board said the research could help in fighting a possible future outbreak.
The study was funded partly by the National Institute of Allergy and Infectious Diseases, which is part of the National Institutes of Health.
U.S. flu vaccines expected to shift from quadrivalent to trivalent, researcher says