That amount of water could erode 50 more feet of unprotected sandy beaches than the current survey assumes and threaten even more homes.

Friedman says it would cost the federal government about $5 million per year to identify, map, and maintain and dissemi- nate information about coastal erosion hazards. This investment, however, could save prospective homeowners, insurers, and government agencies a lot of money, he says.

For example, the study found that if all empty lots in areas susceptible to erosion were left undeveloped, the United States could avoid about $100 million in annual damage to structures alone.

“The only way to stop these losses is to not build on the beach and dunes,” says Susan D. Halsey, coastal geologist with the New Jersey Department of En- vironmental Protection in Trenton.

In 1999, the National Park Service moved the lighthouse at Cape Hatteras, N C , back from the shore, which had eroded to within 160 feet of the landmark. When built in 1870, it was 1,500 feet inland.

“There’s not enough sand in the Sahara to renourish these [eroding] beaches.”

-S. Perkins

DNA vaccine for measles shows promise While many people in industrialized

countries no longer regard measles as a public health threat, the disease still kills more than 1 million people worldwide every year. Many victims are children in developing countries who don’t get vac- cinated. Some of the others are people who received a vaccine that was ineffec- tive because it hadn’t been kept refriger- ated or because they were less than 9 months old when they received the shot.

Scientists working with rhesus mon- keys have now developed an alternative vaccine consisting of copies of just a couple of strands of DNA. It stands up to tropical heat without refrigeration and may confer lasting protection to in- fants only a few months old, says study coauthor Diane E. Griffin, a virologist at the Johns Hopkins University School of Hygiene and Public Health in Baltimore.

Griffin and her colleagues gave 14 ju- venile monkeys two DNA vaccine injec- tions 17 months apart. Of these animals, 11 didn’t come down with measles when exposed to the disease 7 months after the second shot, the researchers report in the July NATURE MEDICINE.

Four unvaccinated monkeys exposed to the measles virus contracted the dis- ease. However, two monkeys that had received the measles vaccine currently in use worldwide proved immune.

The standard vaccine, which was de- veloped in the 1960s, employs a live but disabled version of the virus. This in- duces immune cells to form antibodies to the virus and retain a memory that trig- gers a quick protective response during subsequent encounters with measles.

In contrast, the new vaccine delivers a pair of genes that encode two glyco- proteins essential to the measles virus but incapable of causing illness them- selves. This DNA vaccine produces the

. . proteins within hours of being injected. These compounds, hemagglutinin glyco- protein and fusion glycoprotein, draw the attention of the immune system, which promptly makes antibodies specifically to attack such proteins when it encoun- ters them on a live virus.

Although the DNA vaccine seems to work, puzzles linger, Griffin says. After be ing exposed to the measles, the immu- nized monkeys retained some virus in their bodies. So, they might be largely im- mune but also still somewhat contagious for the disease, she says.

The researchers also haven’t nailed down the best age at which to adminis- ter the DNAvaccine to people. The stan- dard immunization doesn’t “take” early in infanthood because residual antibod- ies to measles from the mother attack and destroy the weakened virus before the body can muster its own immune re- sponse, says James M. Meegan, a virole gist at the National Institute of Allergy and Infectious Diseases in Bethesda, Md. These maternal antibodies gradually fade. When children vaccinated as young infants later contact the real virus, they are unprepared, he says.

“Passively acquired maternal anti- bodies should not affect DNA vaccine uptake and protein synthesis by host cells,” says Ann M. Arvin of Stanford University School of Medicine in the same journal. To ascertain that, Griffin and her colleagues plan to try the DNA vaccine next on infant monkeys.

“We often only get one shot at [immu- nizing a child] in the developing world, and we’d like that shot to be very early in life,” Meegan says. Even so, he says, measles vaccination may evolve into a two-step process, with a DNA vaccination in the first months of life and a standard immunization later. -N &ppa

Gene test probes Neandertal origins

A technique for discerning the similari- ty of DNA specimens supports earlier ge- netic evidence that Neandertals were a deadend species, a new study finds.

Neandertal DNA exhibits substantial genetic differences from the DNA of both ancient Homo sapiens and modern hu- mans, reports a team led by Lutz Bach- mann of the Field Museum in Chicago.

“These data support the hypothesis that Neandertals were not ancestors of anatomically modern [humans],” the sci- entists assert in the June AMERICAN JOUR- NAL OF HUMAN GENETICS.

Bachmann’s team examined DNA from Neandertal fossils from between 110,000 and 50,000 years ago and a H. sapiens fossil from about 35,000 years ago.

The group relied on a standard method for comparing genomes. For each of the fossils, the researchers measured the ex- tent to which the nuclear DNA chemically bonded to nuclear DNA samples from the fossils, modern humans, and chim- panzees. Strong bonds between DNA samples signify a close evolutionary rela- tionship.

Compared with the two Neandertal samples, DNA from the early H. sapiens fossil exhibited a markedly different pat- tern of binding strengths to the set of samples, the researchers say.

Chimpanzee DNA, however, elicited roughly equal amounts of binding from the Neandertal, early H. sapiens, and modern-human DNA samples, they add.

Differences in the binding propensities of DNA from Neandertal and H. sapiens may reflect contrasts in the length of re- peated nucleotide sequences between the species, the investigators theorize. The variations probably evolved rapidly, they argue.

Anthropologist Erik Trinkaus of Wash- ington University in St. Louis views the new genetic findings as inconclusive re- garding Neandertals’ evolutionary sta- tus. This measure, he says, provides a rougher estimate of genetic similarity than studies that compare specific mito- chondrial DNA nucleotide sequences of Neandertals and modern humans (SN: 2/6/99, p. 88).

“[Bachmann’s group] used a crude measure of DNA differences,” Trinkaus says. “How big of a genetic difference is needed to discriminate between two species?” he asks. “Answers to that ques- tion are very subjective.”

Trinkaus argues that fossil evidence shows signs of considerable interbreed- ing between Neandertals and modern humans (SN: 5/8/99, p. 295). Genetic rem- nants of that interbreeding may have di- minished enough over time to escape the notice of current DNA probes, he asserts. - B. Bower

JULY 8,2000 SCIENCE NEWS, VOL. 158 21