Describe how the human immunodeficiency virus (HIV) is replicated once inside helper T cells (TH cells).

HIV-1 is the most common type of HIV. HIV-1 binds to a receptor on TH cells called CCR5.

Current treatment for HIV-1 involves the use of daily antiretroviral therapy (ART) to stop the virus being replicated. Only 59% of HIV-positive individuals have access to ART.

Scientists have found that two HIV-1-positive patients (P and Q) have gone into remission (have no detectable HIV-1). This happened after a blood stem cell transplant (BSCT).

• Patient P was given two BSCTs, and patient Q was given one BSCT.

• All BSCTs came from a donor with TH cells without the CCR5 receptor.

• In addition, patient P had radiotherapy, and patient Q had chemotherapy. Both of these treatments are toxic.

• Both patients (P and Q) stopped receiving ART 16 months after BSCT.

18 months after stopping ART, both patients had no HIV-1 RNA in their plasma, no HIV-1 DNA in their TH cells and no CCR5 on their TH cells.

Use the information given to evaluate the use of BSCT to treat HIV infections.