Human trials for two new HIV vaccines developed by US biotech company Moderna are set to launch this week - A moment that has been described as a “potential first step forward” in protecting people against the deadly virus. Moderna is set to recruit 56 healthy people aged between 18 and 50 into its phase 1 trial, which will assess the safety of the vaccines and their ability to generate a broad range of neutralizing antibodies against HIV. The study is expected to run until May 2023.
The spike-like protein that allows HIV to gain entry to human cells is coated in a sugar residue and hidden away from sight of the body’s antibodies, making it difficult to neutralise the virus. HIV can also linger in the body for years before developing into AIDS. During this time, the virus will frequently mutate parts of its spike protein, to the point that they become almost unrecognisable to antibodies.
The two Moderna vaccines, named mRNA-1644 and mRNA-1574, aim to tackle these challenges by inducing broadly neutralising antibodies (bnABs) to levels not previously reported with other jabs. These antibodies can target multiple variants of HIV, and are capable of neutralising stable parts of the virus that don’t change as much as its mutates.
Professor Robin Shattock, an immunologist at Imperial College London, said, “Moderna are testing a complicated concept which starts the immune response against HIV. It gets you to first base but it’s not a home run. Essentially we recognise that you need a series of vaccines to induce a response that gives you the breadth needed to neutralise HIV. It’s quite likely that their technology may allow them to start to look at that process, but we’re a very long way away from an effective vaccine.”
In a report, Prof Shattock described the progression to human testing as “a potential first step forward on a very long journey”, and acknowledged that it was “exciting” that Moderna’s mRNA technology was being used in a HIV vaccine. Their Covid vaccine delivers genetic instructions to the body which code for the production of the spike protein that coats the outside of the virus.
This triggers an immune response and allows the body to create the necessary defences, antibodies, B cells, T cells, and more, which then provide protection against the real infection. Prof Shattock said, “The mRNA technology may be key to solving the HIV vaccine issue, but it’s going to be a multi-year process. It’s exciting to see that it’s being brought for this very difficult challenge but there is no likelihood of a quick outcome.”
“It remains one of the biggest challenges to overcome in vaccinology. The vaccines may help us accelerate the process, but they won’t be game-changing in terms of solving the fundamental problem, which is knowing how to induce neutralising antibodies.”
