A healthy life Period 5　Reading and Writing

2.what route does hiv take after it enters the body to destroy the immune system?
when hiv is transmitted sexually，the virus must cross a tissue barrier to enter the body.how that happens is still unclear.the virus might invade directly or be carried by a series of different kinds of cells.
3.how does hiv subvert the immune system?
although hiv kills the immune cells sent to kill the virus，there is widespread variation in the rate at which hiv infected people become ill with aids.so scientists ask：can the elements of the immune system responsible for that variability be identified？if so，can they be used to stop progression to aids in infected individuals and possibly prevent infection in the first place?
4.what is the most effective anti－h(huán)iv therapy?
in theory，early treatment should offer the best chance of preserving immune function.but the new drugs do not completely eliminate hiv from the body so the medicines，which can have dangerous side effects，will have to be taken for a lifetime and perhaps changed to combat resistance.the new policy is expected to recommend that treatment be deferred until there are signs the immune system is weakening.
5.is a vaccine possible?
there is little question that an effective vaccine is crucial to controlling the epidemic.yet only one has reached the stage of full testing，and there is wide controversy over the degree of protection it will provide.hiv strains that are transmitted in various areas of the world differ genetically.it is not known whether a vaccine derived from one type of hiv will confer protection against other types.
6.in the absence of a vaccine，how can hiv be stopped?
without more incisive，focused behavioral research，prevention messages alone will not stop the global epidemic.