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Science Friday > Archives > 1997 > December > December 19, 1997

Hour One: The Hong Kong Flu / pharmaceutical Sheep

A small outbreak of a new viral strain of influenza in Hong Kong has scientists around the world concerned.

Seven people in Hong Kong have been diagnosed with a new strain of influenza, and two of those people have died, raising the possibility that a new emerging infectious disease may be on the loose - but scientists still aren't sure.

The virus, formerly found only in chickens, produces symptoms including sneezing, high fever, and aching that are common to many strains of flu. But what makes this particular strain uncommon, however, is the specific coating of proteins on the virus' surface. There are two major types of influenza virus, A and B. Further differences in two specific proteins on the shell of the virus, hemaggultinin and neuramidase, (abbreviated H and N) characterize the strains more fully -- the types of virus expected to be most prevalent this year are the H3N2 and H1 strains of influenza type B. Vaccines must be tailored to deal with specific strains of flu. The current vaccine in use, designed to fight the H3N2 and H1 strains, is unlikely to work against this new threat - categorized as H5N1.

Electron micrograph of several influenza viruses. Proteins coating the surface of each virus create a fuzzy, halo-like appearance. (photo courtesy of Dr. Linda M. Stannard, University of Cape Town. http://www.uct.ac.za/depts/mmi/stannard/emimages.html)

This is the first time that an influenza strain of the H5 type has managed to cross over into humans. Scientists are unsure about how this new type of flu managed to leap the interspecies barrier, although they are warning people to avoid contact with chicken feces and respiratory droplets. They are also unsure about whether or not the disease can be spread from one person to another -- a question that must be answered before the real significance of the threat can be determined.

The Center for Disease Control and Prevention has sent a team of experts to Hong Kong to study the virus, and scientists here are working to try to develop a vaccine for the new strain. On this hour of Science Friday, we'll take a look at the status of the outbreak, and talk about whether or not H5N1 poses a real threat to public health worldwide.

Plus... Early this year, researchers at the Roslin Institute in Scotland stunned the world when they announced that they had, for the first time ever, cloned a mammal -- Dolly, a lamb. This week, a team of researchers from the Roslin Institute and PPL Therapeutics, a pharmaceutical manufacturer, announced in the journal Science that they had succeeded in taking cloning one step further. The team has successfully cloned sheep carrying genes that may allow them to produce medicine for humans in their milk.

The procedure resulted in three sheep, one of which died. The remaining two, named Molly and Polly, each carry genes that code for human Factor IX, the blood clotting factor used to treat hemophiliacs. However, the researchers do not know yet whether or not the lambs are actually producing Factor IX in their milk.

Other methods of inserting foreign genes into livestock have existed since 1985. However, these techniques, involving the injection of genetic material into immature egg cells, have very spotty results. In their new experiment, the researchers use the same techniques used to clone Dolly to insert the genes coding for the Factor IX protein into the nucleus of a cell, clone that engineered cell, and implant the clones into host mothers. The technique results in a consistent batch of animals, all capable of producing the same quality of medicine in the same way each time -- a large improvement over the earlier, more random microinjection technique.

On this segment of Science Friday, we'll talk about the team's work, their experiments, and about what implications their findings might have for medicine.

Listen to this program in RealAudio!

Guests:
Anthony Fauci
Director
National Institute of Allergy and Infectious Diseases
Bethesda, MD

Lee Silver
Author, "Remaking Eden: Cloning and Beyond in a Brave New World"
Professor of Genetics
Princeton University
Princeton, NJ

Books/Articles Discussed:

 "Transgenic Sheep Expressing Human Factor IX Produced by Transfer of Nuclei from Transfected Fetal Fibroblasts" by A.E. Schnieke, A.J. Kind, K. Mycock, A.R. Scott, and A. Colman at PPL Therapeutics, Roslin, Midlothian, Scotland, UK; W.A. Ritchie, M. Ritchie, I. Wilmut, and K.H.S. Campbell at Roslin Institute, Roslin, Midlothian, Scotland, UK; . Science Magazine, Dec 19, 1997.

Related links:
Government of Hong Kong Special Administrative Region Department of Health
CDC Influenza Prevention and Control
World Health Organization info on the outbreak
National Food Safety Database
An explanation of the flu from the WhyFiles

 The Roslin Institute
Science Friday's February 28, 1997 broadcast on the lamb clone