Word: viral
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...first hint that something was amiss came last April, when harbor seals along the coast of northern Europe began showing symptoms of a mysterious viral infection. Before long, dead or dying seals were washing up on the shores of Britain, Holland and West Germany. To date, 11,000 seals have died, including an estimated 70% of the seal population in parts of the North Sea and Baltic Sea coasts...
...Roger Clemens remains the best pitcher in the game, period. Lee Smith and Wes Gardner have provided some order to the chaos that last year reigned in the Red Sox bullpen. Hurst was off to a great start until lately, when he's been affected by some sort of viral infection. Dennis "Oil Can" Boyd and Sellars don't have the records that Clemens and Hurst do, but they have been victimized several times this year by a lackluster offense...
...momentarily safe from scavengers and antibodies, but the free lunch is over quickly. While the B cells are being activated, other helper T cells have been creating an army of killer T cells. These killers recognize the flu-ridden cells because, like macrophages, infected cells display a bit of viral antigen on their outer membranes. Says Coffman: "For many viral infections, the most important response is the killer T cell. Viruses live inside cells, so it's essential to kill not only the viruses themselves but those cells that are infected with the virus...
...killer T cells are relentless. Docking with infected cells, they shoot lethal proteins at the cell membrane. Holes form where the protein molecules hit, and the cell, dying, leaks out its insides. To ensure that the cell and its viral occupants are destroyed, the killer T cells then deliver the coup de grace by transmitting a signal that causes the cell to chew up DNA from both itself and the virus. Explains Dr. Irving Weissman of Stanford: "This is an overlapping, dual system of killing that ensures that the seed of viral production will be eliminated from the body...
While a healthy immune system may take as long as three weeks to complete the job against a specific flu virus, its next response to the same viral strain reaches full force immediately, and the invaders are overcome before they can do any significant damage. In other words, the body has become immune -- but only to that specific virus. "You probably wouldn't even know you'd been reinfected," says Carl Nathan. "The immune system has a short track and a long track, and it all depends on whether it's a first encounter or you've seen it before...