To commemorate World Immunisation Week, we are sharing some of our research in HIV immunity trials. The Desmond Tutu HIV Foundation (DTHF) is testing an infusion of HIV antibodies that are administered intravenously for HIV-negative people. The drip has a similar function to a vaccine; it introduces HIV-fighting antibodies to the patient’s immune system. If successful, this drip could prevent many new incidences of HIV in high-risk communities.
This is one part of the AMP (antibody mediated prevention) study. It is a two-part study focusing on different high-risk groups. The US looking at MSM (men who have sex with men) and Sub-Saharan Africa looking at young women.
At DTHF, the study is aimed at women (aged 19-40) who are at risk of being infected with HIV; women who have unprotected sex, more than one current sexual partner or who inject drugs. The study, which began in 2016, aims to recruit over a hundred at-risk women in total to trial the HIV-prevention infusion. Tests have already begun and are predicted to finish in 2020.
An HIV vaccine has been tricky to produce because the virus changes a little every time it replicates. Consequently, the bodies’ antibodies have a hard time recognising the virus as a threat.
Explanation of how the infusion can prevent HIV infection | AMP
The infusion, called VRCO1, is a broadly neutralising monoclonal antibody that can attach to HIV and neutralise it. This makes the virus harmless, and the patient can’t get infected. ‘Broadly neutralising’ refers to the strains of HIV that the infusion targets: The antibodies in the infusion can attach themselves to and neutralise a broad range of HIV strains. However, the body naturally metabolises the infusion after eight weeks, and the patient no longer has any protection against the virus, leaving them vulnerable to infection again.
The aim of this study is to ascertain whether the infusion will prevent HIV infection. The trial uses three different types of infusion: two different concentrations of the VRC01 product and one placebo. The study is double-blind, so neither the patients or trial managers know which infusion each patient receives. The women also receive STI checks, pregnancy checks, advice and contraceptives, including condoms.
Currently, no one on the study receives the once a day the once-a-day pill that fights off the virus (PrEP) as well, though this will likely change once PrEP becomes more widely available in South Africa. Currently, HIV-negative people can access PrEP through a demonstration programme or buy it on prescription.
As of yet, no one has received a positive diagnosis of HIV since being on the infusion at our site. However, the trial is still in its infancy so these results could change. Patient response to the infusion has been very positive: retention has been high. The group has also created a community around the trial: hosting events for health information and reflection.
If the infusion proves to be successful at the end of the trial, then it will be a good proof of concept. Prof Catherine Orrell, the Principle investigator in the DTHF treatment division, notes that the infusion in its current form wouldn’t be a viable long-term solution. An intravenous drip every eight weeks for every high-risk person for the rest of their lives isn’t practical. Currently, it is a proof of concept that could lead to a number of products. “Subcutaneous injections that would last a bit longer that patients could self-administer, for example.”
Written by Caroline Reid