Getting the Jump on Avian Influenza - US - This report by Tom Ventsias discusses how in 1997, scientists and public health officials worldwide became quite concerned when an outbreak of avian influenza in Hong Kong infected 18 people, killing six of them. The virus's path was eventually traced to live chickens sold in the local markets, which in turn had infected humans who came in contact with the sick birds.

What most alarmed researchers was that the virus, known as type H5 influenza, was able to "jump" from its natural avian hosts to humans for no apparent logical reason.

This still-unexplained interface between avian and human influenza demands a much closer scrutiny, says Daniel Perez, an assistant professor of virology in the Virginia-Maryland Regional College of Veterinary Medicine. Perez recently arrived at the University of Maryland from St. Jude's Children's Hospital in Memphis, Tenn., and is currently looking at new methods of identifying and controlling the inter-species transmission of influenza.

"My interest in this research," Perez says, "is to make people aware that while understanding and preventing avian influenza is important [for economic reasons] in the poultry industry, it is also very important from a public health point of view." He mentions other instances of various influenza strains jumping from their natural animal host to humans, the most significant case being the 1918 Spanish Flu pandemic that killed an estimated 20 to 30 million people. While not completely proven, many scientists think that the 1918 flu outbreak in humans originated from a form of swine influenza.

A new research tool that will greatly help in current efforts to identify the inter-species transmission of influenza is a process known as plasmid-based reverse genetics. "That is the key," Perez says. "We can now manipulate the [influenza] genome in any way we want. We are talking about cloning a virus into units of DNA that we can mutate."

The typical influenza virus has eight segments of RNA, Perez explains, and each one of those eight segments can then be cloned into a plasmid DNA unit. Those units, in plasmid DNA form, are then very easy to manipulate, he says, allowing scientists to investigate the genetic markers that give a virus the potential to cross the species barrier. This plasmid-based reverse genetics process was unheard of until about four years ago, and Perez was involved in the original research to perfect this new technique.

Ultimately, Perez hopes that his research at Maryland will lead to a vaccine that prevents the inter-species transmission of influenza. At the very least, he says, the plasmid-based reverse genetics process has already allowed scientists to greatly speed up the process in developing certain vaccines for potentially pandemic forms of human influenza.

Source: University of Maryland - 16th December 2003