Science / Medicine : ‘Gesundheit!’ : Brash Young Researchers Make Inroads Against the Cold Bug

In a sparkling research center here within sight of Long Island Sound, a brash team of young researchers is stalking the common cold. Using the newest and most sophisticated techniques of molecular biology and genetic engineering, they are making inroads against one of humanity’s oldest enemies, the sniffling and sneezing that have plagued people at least since the beginning of recorded history.

These researchers at Molecular Therapeutics Inc. (MTI) believe they can block the cold viruses’ ability to cause infection. If they are right, when your child comes home from school with the third cold of the winter, or when everyone at the office is sneezing cold germs at you, you might one day be able to spray a drug up your nose and not catch cold.

Three hours’ drive north on I-95, a Harvard Medical School pathologist named Timothy Springer and postdoctoral fellow Donald Staunton are performing nearly identical experiments. And both groups are looking back anxiously over their shoulders at the Rahway, N.J., research lab of pharmaceutical colossus Merck Sharpe & Dohme, where molecular biologist Richard J. Colonno has been working for at least five years trying to learn how to prevent colds.

Until recently, the Massachusetts and Connecticut groups labored in anonymity. As recently as a year ago, they did not even know of each other’s existence.

In March, however, the two groups simultaneously reported in the journal Cell that they had identified and cloned the cellular receptor to which cold-causing rhinoviruses bind in their assault on the nose.

By identifying the receptor, both groups believe they are well along the way to developing agents that can interfere with the binding, thereby preventing colds and perhaps even alleviating the symptoms of colds that have already developed.

The common cold has probably been around nearly as long as humankind and is virtually ubiquitous. “It’s the most common disorder,” said microbiologist Robert Couch of the Baylor University College of Medicine in Houston. “There’s nothing else in the world that matches it.”

Normal people contract 100 colds during their lifetimes, an average of almost two per year. Young children can catch as many as 12 a year. According to the 1987 National Health Survey, colds cause 79.5 of every 100 U.S. males and 94.5 of every 100 females to miss at least two days of work or school each year.

Colds are caused by viruses, small packets of genetic information enveloped in a coating of proteins, that thrive in the relatively cool environment of the nose, about 91.4 degrees Fahrenheit.

There, the viruses attack cells of the mucous membranes that line nasal passages, producing congestion, sneezing and nasal drip. Some also cause aches, fever, coughing and chills. Colds take two to three days to develop after the initial infection, and persist for a week. Cough syrups, antihistamines, decongestants, chicken soup and vitamin C may make the victim more comfortable and reduce the total length of the cold to seven days.

During the 1940s and ‘50s, scientists had high hopes that isolation of “the virus” that causes colds would quickly lead to the development of a vaccine. But researchers soon found that colds are caused by as many as 200 viruses, about 115 of which belong to a family called rhinoviruses from the Greek word for nose.

Although the large number of cold viruses effectively precludes the development of a cold vaccine, cold researchers took new hope from Colonno’s discovery in the mid-1980s that as many as 90% of rhinoviruses enter cells by binding to one protein on cell surfaces.

Tests in humans in 1986 showed that spraying a solution of the antibodies against this receptor into the nose covered the receptors on nasal cells, inhibiting the binding of rhinoviruses and preventing colds.

Although Colonno abandoned this specific approach because of fear that the antibodies, which were produced in mice, might trigger an allergic reaction, the tests did suggest that preventing binding of the virus and receptor could prevent colds.

At about the same time that Colonno was discovering the rhinovirus receptor, the German chemical and pharmaceutical giant Bayer AG was creating MTI as its own entry into the biotechnology industry and staffing it with bright young scientists who had cut their teeth on the sophisticated new technologies of genetic engineering and monoclonal antibodies.

“We’re really the first generation of scientists that have been trained since these technologies were developed, and I think we look at things a little differently,” said Michael E. Kamarck, 38, who is second in command at MTI.

As one of its first projects, MTI decided to go after the rhinovirus receptor, even though Colonno was probably also pursuing it.

“These days, you’re lucky if you have only one major competitor,” said cell biologist Jeffrey M. Greve who, along with molecular biologist Alan McClelland, was one of the principal scientists on the project.

The team also thought they had an additional advantage over Colonno: McClelland, Kamarck and molecular biologist George A. Scangos, head of MTI, had all worked in the Yale University laboratory of molecular biologist Frank Ruttle, where the use of genetic engineering techniques to isolate cellular receptors had been pioneered.

McClelland, 33, a tall, slender Scot trained at the universities of Edinburgh and London, used techniques developed in Ruttle’s lab to search for the rhinovirus receptor. Greve, 35, who had specialized in isolating extremely small amounts of proteins at Washington University in St. Louis and Harvard, sought to determine the chemical composition of the receptor.

Isolating the receptor was straightforward, albeit time-consuming. Using genetic engineering techniques, McClelland broke the DNA from human cells into small segments containing about 100 genes each and inserted each segment into mouse cells, which do not have rhinovirus receptors. He isolated the human DNA from mouse cells that had acquired the receptor and repeated the process.

Eventually, he obtained mouse cells that contained only one human gene--the rhinovirus receptor--and isolated the human DNA from the cells. That was the only point at which the MTI team encountered difficulties, Kamarck said. “There were three or four times when we were sure we had it (the gene), but didn’t,” he said. “We had incredibly bad luck in terms of the way nature designed the gene. It was a rough period of time.”

Meanwhile, Greve was working with bits and pieces of the receptor protein isolated from the mouse cells with special antibodies, using these pieces to identify the sequence of the 500 separate amino acids that make up the protein. After a year and a half, he had identified about 150 amino acids.

Molecular biologist Gary Davis, the acknowledged “computer jock” of the MTI group, had regularly been checking Greves’ sequence information against computerized data based of protein structure to see if anyone else had isolated the protein. One night last fall, he checked it against a new German database he had learned about on a recent visit to West Germany and got a match.

The moment was bittersweet, Davis recalled recently. “There it was in front of me what we had spent two years working on,” he said. And someone else had gotten it first.

That someone was Springer. In the spring of 1988, he had published a paper describing the characterization of a protein called intercellular adhesion molecule-1, or ICAM-1. To the MTI group’s relief, Springer’s paper said nothing about rhinoviruses.

Springer, in fact, had been studying an entirely different problem, how specialized white blood cells (also known as lymphocytes or leukocytes) called killer T-cells bind to and destroy cells infected by viruses. “Viruses are replicating inside the cells, so it is important to kill the cells that contain the viruses, just stop the replicative process,” he said.

Early on, he found that the killer T-cells contain a protein, called lymphocyte function-associated antigen-1 or LFA-1, that binds to the infected cells.

In 1979, researchers recognized a group of children who have severe, recurring bacterial infections and cannot fight them off because their killer T-cells will not leave the blood stream to accumulate at the site of the infection--in short, they cannot form pus. “These children frequently die unless you give them a bone marrow transplant” to provide new killer T-cells, Springer said. Springer showed that these children have a defective gene for LFA-1.

That discovery provided an improved way to diagnose the genetic disease, called leukocyte adhesion deficiency. Blood cells from the children also provided him with a valuable research tool, easing the task of searching for the protein on cells that LFA-1 binds to.

Working first at the Dana-Farber Cancer Center and later at the Center for Blood Research, and using techniques not greatly different from those employed at MTI, Springer isolated that protein and found that it was ICAM-1. ICAM-1 belongs to a group of molecules, “integrins,” that hold the cells of the body together much like nuts and bolts hold a car together.

“When we saw Colonno’s papers, it looked like sort of deja vu, that we were looking at ICAM-1,” the bearded Springer said. Springer and Staunton began growing rhinoviruses and showed that they bound to ICAM-1. Along the way, they made contact with the MTI group and agreed to publish their papers simultaneously.

Both groups are now following up on their discovery in the same manner. ICAM-1 is too big and too insoluble in water to be used for experiments, but both groups have chopped off inessential portions of the molecule to produce smaller, soluble derivatives. The MTI group has shown that--at least in the test tube--this small molecule can bind to rhinoviruses and prevent them from infecting cells.

Their hope is to find a small protein fragment or artificially synthesized molecule that could be sprayed into the nose, where it would bind to rhinoviruses and prevent the individual from getting sick.

Scangos emphasized, however, that any drug they isolate will have to undergo extensive safety testing. “Colds are not life-threatening,” he said, “and if there are any risks, it is not acceptable.” Any potential drug used for preventing colds, he said, must be “absolutely, unequivocally safe.”