Examining Immune Cells Where HIV Can Lie Dormant
Researchershave determined how HIV is able to lie dormant in certain immune system cellsand prevent the cells from self-destructing, according to a study publishedThursday online in the journal Retrovirology, the AP/Google.comreports. HIV often resides in CD4+ T cells because the cells can survive for"years" or "even decades," according to the AP/Google.com.HIV also can lie dormant in macrophages, another immune system cell thatattacks invading viruses or bacteria. Although macrophages are supposed toself-destruct if they are harmed, HIV is able to keep the cells alive pasttheir typical lifespan, the AP/Google.com reports.
For the study, Baek Kim from the University ofRochester andcolleagues discovered that HIV produces a protein that initiates a specificcell-survival pathway. The researchers found that the protein ultimatelytriggers an enzyme, called Akt, that prevents macrophages from self-destructingand allows HIV to remain dormant. According to the researchers, it might befairly straightforward to block the enzyme from hindering the cells'destruction, thereby eliminating the macrophage "hideout," theAP/Google.com reports. The study also found that miltefosine, a drug currentlyused for leishmaniasis, can block the Akt pathway. Perifosine, a drug beingstudied as a possible cancer treatment, also blocked the enzyme's pathway, thestudy found.
Kuan-Teh Jeang -- an HIV specialist at NIH and editor-in-chief of Retrovirologywho was not part of the study -- said, "Up to now, nobody has reallythought about how to eliminate the macrophage reservoir," adding that the"imagination now has turned toward, 'How do we eliminate reservoirs?' ...The best way to address our problem is to simply kill those cells." Jeangnoted that the evidence the researchers "show is in fact prettygood," adding that the next step should be to test miltefosine in monkeysinfected with SIV. Kim said that he next plans to study the use of miltefosinein animals to determine if the drugs targets HIV-infected macrophages."It's a very smart virus," Kim said, adding, "They have to havea very good fence to protect their house for a long time. ... Get rid of thefence, and now their house is gone" (Neergaard, AP/Google.com, 1/31).
Andrew Dayton of FDA's Center for Biologic Evaluation and Researchin an accompanying commentary said the study's findings are "welcome newsas delineating a possible novel therapeutic approach" to HIV. He added thatthe findings make "therapeutically attacking" the HIV macrophagereservoir a "tantalizing possibility" (Dayton, Retrovirology, 2/1).
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