11.   The tests may also be well-suited for pregnant women and newborns, since cases have been recorded of mothers passing resistant virus to babies.

12.   The tests also are well-suited for pregnant women and newborns, Thompson said, since cases have been recorded of mothers passing resistant virus to babies.

13.   Thus, the greatest challenges now are to develop novel classes of anti-HIV drugs and new members of older classes that are active against resistant virus.

14.   Typically, they now discover a patient has a resistant virus only when the drug regimen fails to suppress the virus promptly.

15.   In addition, the drug appears to suppress the development of new varieties of resistant virus.

16.   Missing just a few doses allows resistant viruses to grow explosively.

17.   Now, however, doctors say these resistant viruses apparently are being passed on to others in significant numbers.

18.   Several variations of a new protease inhibitor are being developed by Tibotec of Rockville, Md., that seem able to attack these resistant viruses.

19.   The advantage of new classes of drugs is that they will work against all the currently resistant virus.

20.   The easy emergence of resistant viruses may have consequences for others, as well.