mothers gaze at the camera in Zuiginchor, Senegal. The battle against
the AIDS epidemic has been more effective in Senegal than most African
If your enemy is a virus, your ultimate weapon is the human immune system, which effortlessly makes chemicals and cells that destroy viruses and other pathogens. When you get chicken pox, you get sick, but the immune system normally kicks in and attacks the enemy.
Once the virus has been defeated, a few cells specifically targeted to that infection linger, ready for the next infection. These "memory cells" explain why you normally can't get chicken pox twice.
Although the immune system is smart, it sometimes needs an introduction -- via a vaccine -- to its enemies. Vaccines "prime" the immune system with a glimpse of the enemy -- say a part of a live virus, or a killed whole virus. You don't get sick, but your immune system "remembers" the pathogen with weapons ready to attack next time around.
AIDS belt. In these countries, more than 10 percent of people aged 15
to 49 are infected with HIV.
Vaccines are older than microbiology. Back in 1796, long before viruses were known, Edward Jenner, an English doctor, invented the smallpox vaccine. Eventually, in 1980, vaccine made smallpox the first and only disease ever eradicated.
In the 1950s, two vaccines banished the paralytic scourge of polio. These days, you can get vaccinated against measles, mumps, yellow fever, some forms of hepatitis, and a bunch of other diseases.
Not exactly. Instead, AIDS vaccine research fumbled for a decade:
As time passed and AIDS-prevention failed, particularly in Africa, HIV became the best-studied virus in history. Problems with vaccines were due to the shifty, malign HIV, which:
late than never
Today, spurred by the relentless growth of the epidemic and new discoveries in immunology, vaccine research is arising from the ashes. With luck, effort and money, we might see an AIDS vaccine -- or a therapy that prevents immune collapse -- in a decade or less. Or maybe never.
Are there some promising vaccines and related immune therapies?
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5 pages in this feature.
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