The Buenos Aires Patient shows important differences to the Berlin Patient

According to researchers from Buenos Aires and the US National Institutes of Health (NIH), a woman, now in her 50s, stopped taking her HIV therapy due to side effects in 2007. Fourteen years later she continues to have an undetectable viral load. Researchers consider the case of the 'Buenos Aires Patient' to be unique, writes Aidsmap.

The woman was hospitalised in 1996 at the age of 37 with a severe unknown illness. She was then diagnosed with HIV and toxoplasmosis. The woman was treated in hospital and then began antiretroviral therapy (ART) with zidovudine (AZT), didanosine (DDI) and nevirapine (NVP) before being discharged from hospital.

She achieved an undetectable viral load (less than 50 copies/mL³), expect for one small spike in 2001. Treatment was changed several times due to side effects, and the development lipodystrophy.

In 2007 the woman stopped taking her ART due to continued issues with lipodystrophy. From that date in 2007 until February 2020 (the date of last measurement) she has maintained an undetectable viral load and a CD4 count of above 500 copies/mm³.

The woman underwent medical examinations at the NIH in 2015 and again in 2017. The researchers analysed blood, various tissue samples and cerebrospinal fluid. The results were compared with samples of HIV-negative control group and people with chronic HIV infection.

The NIH researchers have found:

• Plasma viral load was below 0.2 copies / ml (detection limit on the most sensitive test available) and HIV RNA was not detected in any lymphoid tissue sample.
• HIV DNA was not found in colon tissue or mononuclear blood cells but was found at very low levels in lymph node tissue.
• Replication-competent HIV was found at "very low" levels in CD4 T cells.
• No antibodies to HIV were found.
• HIV-specific CD8 + T cell responses, which would indicate the presence of HIV, were weak. HIV-specific CD4+ responses, however, were higher than HIV-negative control groups.

Researchers consider the case of the patient from Buenos Aires "extremely unique." The loss of antibodies (seroreversion) is not only one of the longest documented examples of post-treatment HIV control but is also very unusual.

The Berlin patient, one of two people who recovered from HIV after bone marrow transplantation, retained antibodies to HIV even after recovery. The researchers say the loss of antibodies is the result of a long period of life with "extremely low" HIV antigen levels.

"This case may represent the best example of post-treatment functional cure and ... offers hope for a lasting remission without the need for overly toxic interventions," the researchers conclude. However, researchers have been unable to explain how her HIV has been controlled since the woman stopped treatment in 2007.