Cats do not get HIV as people get, but they do get FIV. You are right, this is can be transmitted to the kittens. But recent evidence says that queens infected prior to the pregnancy may not give it to the kittens. I would recommend having the kittens tested for FIV at 6 weeks of age and to have the mother spayed as soon as possible. Here is a website with some information on FIV.
http://www.peteducation.com/article.cfm?cls=1&cat=1354&articleid=213
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Dr. Louis Gotthelf
Animal Hospital of Montgomery
Pet Skin and Ear Clinic