Pathogens, Host-Cell Invasion and Disease
Invading pathogens can co-opt even the cells of the immune system. New anti-infective drugs may arise from an understanding of this chemical warfare
Since the dawn of civilization, infectious diseases have shaped human history. In the Middle Ages, Europe lost up to a third of its population to plague outbreaks. The Spanish flu outbreak during the winter of 1918–19 killed more people—between 25 and 40 million—than did World War I. It was not until 1941, with the development of penicillin, that science could offer a potent weapon against infection, at least against bacterial diseases. But modern medicine is far from having won the war against pathogens, organisms that cause disease. Infectious diseases, including AIDS and malaria, are a severe health problem in the Third World. And in the developed world, bacteria are becoming increasingly resistant to the antibiotic drugs available to combat them.
To develop new treatments against infectious diseases, whether caused by viruses, bacteria or higher microorganisms, it is important to better understand the nature of infection—the mechanisms and strategies that pathogens use to invade the body's cells as well as overcome the body's defenses against them. New approaches are needed that do not trigger evolutionary countermoves by the pathogens. Such strategies, we hope, might arise from a better understanding of the ways pathogens invade host cells and evade the immune system—an area of research neglected while antibiotics provided easy answers, but clearly essential to providing new weapons for the continuing battle against infectious disease. Recent research has therefore been concentrating on the mechanisms that infectious agents use to gain entrance to their target cells as well as the strategies that the host evolves to prevent them from doing so. Using this knowledge, drug developers will eventually be able to develop new anti-infective medications that prevent pathogens from penetrating host cells. Investigators hope that strengthening the host's defenses, rather than attacking the pathogens directly, will provide therapies against infectious disease that are more durable over the long term than those offered by antibiotics.