Analysis Suggests a More Virulent Swine Flu Virus in the Indian Subcontinent

A flu outbreak in India that has claimed more than 1,200 lives may not be identical to the 2009 North American strain, as recently reported in India. A comparative analysis conducted by scientists at the Massachusetts Institute of Technology (MIT) shows that the flu virus in India seems to have acquired mutations that could spread more readily and therefore requires deeper studies. As flu season in India winds down, the researchers call on officials to increase surveillance of this and future flu outbreaks and rethink vaccination strategies to account for potential new viruses.

The MIT analysis, which compared viral proteins important for virulence and transmissibility in the 2009 and 2014 flu epidemics, was conducted by professor Ram Sasisekharan, PhD, at the Koch Institute for Integrative Cancer Research, and his research scientist colleague Kannan Tharakaraman, PhD. It appears in the March 11 issue of the journal Cell Host & Microbe.

"It has been extensively reported in India that a virus similar to A/California/07/2009 is responsible for the current outbreak," Sasisekharan says. "Examination of the Indian H1N1 flu viruses that circulated in 2014 shows amino acid mutations that make them distinct (in terms of receptor binding, virulence, and antigenic drift) from the A/California/07/2009 virus."

"It is widely believed that the current H1N1 flu vaccine is still effective for the most part," he adds. "Effectiveness of the current H1N1 flu vaccine is debatable, and there have been calls for updating the vaccine. The Indian H1N1 viruses that circulated in 2014 are different compared to the 2009 vaccine strain A/California/07/2009."

A lack of rigorous scientific information is resulting in conflicting reports on the 2014 Indian flu outbreak. The authors of the current study also note that since 2012, the number of viral sequences submitted for public analysis from India has been limited relative to the population that is susceptible to being infected by the virus. Adequate monitoring of influenza viruses in animal populations, which enables real-time surveillance in humans, has also been limited.

"In many ways the handling of the H7N9 outbreak in 2013 represents a scientifically robust way in which to handle such an infectious disease outbreak," Sasisekharan says. "Sequences of the virus were rapidly made available to the scientific community, the phenotype of the virus was measured in controlled studies, and the results were disseminated in scientific publications. At the same time, vaccine strategies were developed."

"While there certainly is a delay between the advent of such an outbreak and the availability of vaccines, I believe that the robust scientific discussion that occurred in 2013 facilitated an understanding of the virus and a discussion of appropriate countermeasures to stop the virus from spreading," he says. "I believe that this model should be built upon, enabling information to cross borders."

This work was funded in part by National Institutes of Health Merit Award, a National Institute of Allergy and Infectious Diseases Award, the National Research Foundation-supported Interdisciplinary Research group in Infectious Diseases of SMART (Singapore MIT alliance for Research and Technology), and the Skolkovo Foundation-supported Infectious Diseases Center at MIT.

Reference: Tharakaraman K. and Sasisekharan R. Influenza Surveillance: 2014-2015 H1N1 'Swine'-Derived Influenza Viruses from India. Cell Host & Microbe.

Source: Cell Press