[单项选择]
HIV & AIDS
AIDS has now surpassed the Black Death on its course to become the worst pandemic in human history. At the end of 2004, 20 million people had been killed by it, and twice that number is currently infected with HIV. Barring a medical breakthrough, it could claim the lives of some 60 million people by 2015. AIDS exerts a terrible toll on societies, crippling their economies, decimating their labor forces and orphaning their children.
Nine out of 10 people living with HIV are in the developing world; 60 to 70% of those are in Sub-Saharan Africa. But the disease is spreading in every region, with fierce epidemics threatening to tear through countries such as India, China, Russia and the islands of the Caribbean. The statistics are sobering — in some Southern African towns 44% of pregnant women are HIV positive, in Botswana 37% of people carry the virus.
Immune assassin The human immunodeficiency viru
A. It breaks into the cell and reproduces itself.
B. It uses the CD4 receptor to bind with the RNA of the cell.
C. It integrates into the DNA of infected cells.
D. It destroys the cell’s RNA and multiplies inside it.