Science Editor

Editor's note: Science Scan is a roundup of recently published biotechnology-relevant research.

Coxsackie, Ebola, Hantaan, Lassa, Marburg, Rift Valley, Semliki, Sendai, Sindbis, West Nile.

Q: What does that random list of lately in-the-news viruses have in common?

A: They all were named for places on the globe where they were first found.

An exception is the dengue virus, now experiencing a significant flare-up in hot regions of Africa, Asia and Latin America. (For the record, it was first described in 1780.) Dengue's moniker derives from Swahili, the lingua franca of East Africa. "Ki denga pepo" is its original etymology, which stands for the phrase "It is a sudden overtaking by a spirit."

Nowadays, and closer to home, the spreading severe dengue virus infection includes the immunological tagline "original antigenic sin."

Dengue fever is a peculiar illness. Rather than develop resistance to its infection, people who contract the fever often get sicker the second time they are infected. In a study of Thai volunteers, published in the July issue of Nature Medicine, research immunologists at Oxford University in the UK discovered why infection with any of the four subtypes of the dengue virus mobilizes immune cells that promote virus destruction. But in volunteers infected a second time with a different strain, immune cells mobilized mainly against previously encountered strains. This misdirected immune reaction barely fought off the new infection. What's more, some immune cells seemed to self-destruct, exacerbating the problem.

The Nature Medicine article is titled "Original antigenic sin and apoptosis in the pathogenesis of dengue hemorrhagic fever."

The phenomenon dubbed "original antigenic sin" presents a barrier to vaccine development. Any vaccine could in principle act like an original infection, and thus promote dengue infection instead of protecting against it. The new research results should help break down barriers to vaccine development for this mosquito-borne disease.

Worldwide, hundreds of thousands of people contract dengue fever each year, and many require hospitalization. Most of the deaths from that virus occur after a second infection.

Dengue's airborne nemesis is a particularly vicious mosquito called Aedes egypti, which also transmits yellow fever. But for dengue there is no vaccine, no specific therapy. Its other name is "breakbone fever" - for a reason, though it's not fatal. Of late, though, a new and deadly form of the infection has emerged, dengue hemorrhagic fever (DHF), also known as dengue shock syndrome. It can kill infants and young children bitten repeatedly by Aedes egypti. (See BioWorld Today, May 15, 1996.)

"There are hundreds of thousands of cases of DHF each year," the journal paper notes, "and without appropriate treatment mortality can be over 20 percent." It makes the added point that more than "2.5 billion people are at risk of dengue virus infections, and there are up to 50 million people infected each year." Epidemics are common in southeast Asia, South America and the western Pacific.

"In this report," the paper concludes, "we chose to use the term original antigenic sin' to denote the resurrection from immune memory of a response, without prejudice as to whether this will be to the benefit or the detriment of the host. Antigenic sin has the advantage that it can lead to the rapid mobilization of a memory response, which in many instances may be advantageous."

Bacterium Promises Striking Bioremediation To Clean Contaminated Aquifers, Drinking Water

A newly discovered bacterium could prove valuable in the bioremedial fight against pollution. The just-discovered microbe mops up harmful inorganic chlorides, as reported in the July 3, 2003, issue of Nature. The paper is titled "Detoxification of vinyl chloride to ethene coupled to growth of an anaerobic bacterium." Its authors are scientists at the Georgia Institute of Technology in Atlanta.

The microbe uses dichloroethenes and vinyl chloride to aid its energy metabolism. The disc-shaped bug can survive in the absence of oxygen, which is encouraging, as the pollutants often are present in oxygen-poor environments. Dichloroethene is a potent toxin, and vinyl chloride is notorious for causing cancer. Both pollutants arise through the contamination of groundwater with commonly used organic solvents. The authors suggest that the microbe offers a cheap and relatively quick way to clean contaminated aquifers.

Vinyl chloride was found in at least 496 of the 1,430 National Priorities List sites identified by the U.S. Environmental Protection Agency, the paper notes. Its precursors, PCE and TCE, are present in at least 771 and 852 of the sites, respectively.

"A recent pilot demonstration," the article concludes, "in a hydraulically controlled recirculation test plot supports bioaugmentation with the new microbe as a promising approach. Such innovative technologies are needed to clean up numerous chloroethene-contaminated aquifers at reasonable costs within acceptable timeframes, and to protect threatened drinking water reservoirs."

Ad Hoc Consortium Calls For Global HIV Vaccine Research Centers As Bookends To Latest Results

In its issue June 27, 2003, BioWorld Today reported news from Science on giant steps toward developing a vaccine against HIV, the AIDS virus. The same-day issue of Science also carried a follow-up "Policy Forum" supplement that complements the first article. Its title: "The need for a global HIV vaccine enterprise."

It noted that despite approximately 20 years of effort since the discovery of HIV, the world has no effective preventive HIV vaccine. In this five-page forum, many of the world's foremost HIV vaccine researchers and advocates describe the need for a global, public-private, HIV vaccine enterprise.

Harnessing the creativity of scientists working in multidisciplinary problem-solving consortia linked to vaccine development capabilities is the best way to drive the HIV vaccine discovery effort, the co-authors point out.