HIV vaccination: A step closer thanks to COVID-19 vaccines?

Vaccine prospects were revolutionised thanks to new mRNA vaccines against COVID-19. Can this knowledge transfer for the HIV vaccine quest?

HIV vaccination in a nutshell

Vaccines: from rapid market introduction to decades of research

Developing a vaccine is a lengthy and difficult undertaking. Whereas it took only one year to bring a vaccine against COVID-19 to market, work on a vaccine against HIV has now been going on for 32 years - so far without success, even though promising research approaches are already available.1

Not all viruses are the same

Why is it so much more complex to produce a vaccine against HIV than against SARS-CoV-2? Prof. Dr. med. Morris provides the answer: It is due to fundamental differences between the two viruses. While COVID-19 is an acute viral disease that the defence system can fight after some time, AIDS is a chronic, persistent disease in which the pathogen integrates into the DNA. Furthermore, the HI virus genome is far more mutagenic than that of SARS-CoV-2.

The main problem, however, is the immune response, especially to the HIV envelope glycoprotein. The neutralising antibodies (AK), which are supposed to increase through immunisation, only appear in HIV after years and also only in a minority of those affected. With COVID-19, on the other hand, almost all persons produce such AK within a few weeks.1

HIV: AK increase thanks to VLPs

Although the effort to develop an HIV vaccine is difficult, there have already been first successes.1 For example, a preclinical study by Zhang et al. showed that the administration of mRNA-based virus-like particles (VLPs) significantly increased the production of AK in animal experiments.2 Although the VLPs are not nearly as effective in AIDS as an mRNA vaccine against COVID-19, these results are nevertheless encouraging and could help achieve a stronger and lasting immune response in HIV infection.3

Immunisation against HIV needs more than a standard vaccination

Despite the positive trial data, however, it is important to remember that the main problem for vaccine research is the structure of the HIV envelope glycoprotein. Because of the years it takes for infected individuals to produce neutralising AK, it can be assumed that there is co-evolution between the virus and AK. This allows the hypothesis that an HIV vaccination regime must be adapted to these conditions. The immune system must be trained, so to speak, to produce the AK itself - and this during the entire period of illness. The consequence is that a variety of different vaccines have to be developed and multiple administered immunisations. All in all, this is a more complex undertaking than other vaccination regimens.1

Conclusion on the HIV vaccine

The mRNA vaccine development against COVID-19 has taught us a few things. In particular, Prof. Morris emphasised the importance of a parallel or simultaneous approach: in addition to research, production and approval processes, funding must be secured. In addition, there must be a guarantee that countries will also purchase new vaccines.1 Whether the findings from mRNA research will lead to the development of an HIV vaccine remains to be seen.

For more articles, please visit our dedicated AIDS 2022 congress page

 

References: 

  1. Morris, Lynn. Prof. Dr. med., Universität von Witwatersrand, Johannesburg, Südafrika. Vortrag: Introduction to mRNA for HIV vaccine. Sitzung: Will mRNA lead to a long-awaited HIV vaccine?, AIDS Kongress 2022, Montreal, 30.07.2022.
  2. Zhang, P., Narayanan, E., Liu, Q. et al. A multiclade env–gag VLP mRNA vaccine elicits tier-2 HIV-1-neutralizing antibodies and reduces the risk of heterologous SHIV infection in macaques. Nat Med 27, 2234–2245 (2021). https://doi.org/10.1038/s41591-021-01574-5.
  3. Morris, L. mRNA vaccines offer hope for HIV. Nat Med 27, 2082–2084 (2021). https://doi.org/10.1038/s41591-021-01602-4.