Thursday 7 November 2019

Comment from British HIV Association spokesperson, Anna Maria Geretti, Professor of Virology & Infectious Diseases, University of Liverpool

Ref Journal of Acquired Immune Deficiency Syndromes (JAIDS), 6 November 2019: link to article: https://journals.lww.com/jaids/Abstract/publishahead/Complete_genome_sequence_of_CG_0018a_01.96307.aspx

We have known for years that different variants of HIV exist and know that some have important differences in their propensity to be passed on or cause disease. There are two main types of HIV: HIV-1 and HIV-2, each of which has a number of different variants, called groups and subtypes.

HIV-1 group M viruses cause the vast majority of infections in the UK and the rest of the world. Group M viruses subdivide into subtypes and there is a strict scientific consensus about how a subtype is identified and classified. We already knew of subtypes A to K and various mosaic viruses formed by intermixing. The investigators of this study used cutting edge technology to characterise subtype L.

Is identification of the new subtype surprising?

Is the identification of a new subtype of HIV-1 group M surprising? Not really, as we already had preliminary evidence that a subtype L might exist and can predict that new variants of HIV will continue to emerge while the infection continues to spread. The likelihood is highest where there is ongoing transmission in the population.

Why is the finding important? Because it serves as a reminder that we need to make sure our diagnostic tests keep up with what we may define as the plasticity of HIV, that is with the frequent changes that can occur in the virus genetic make up. It also reminds us that the only way to prevent further HIV variants emerging is to ensure HIV transmission is halted. We have the necessary tools: treatment of HIV with antiviral drugs is the most effective intervention, as those who take effective treatment do not transmit HIV. We also have the tools to prevent infection for those at risk of infection, for example, the use of antiviral drugs to prevent sexual transmission or vertical transmission (mother to child), as well as other protective measures such as condom use, screening of blood donations, and safe health care practice when dealing with needles, for example.

What else is important about the finding? People may worry that drugs to treat HIV may not be as good against certain variants of HIV. However, we have our own UK data to provide reassurance: HIV infection in the UK is highly diverse in terms of the variants of HIV-1 group M that circulate with many different subtypes and mosaic strains. We collect data routinely about the virus genetic make up and about treatment responses among people with the virus, and through this surveillance work have previously shown that different subtypes of HIV-1 group M respond equally well to available drugs. There is a need to remain vigilant, of course.

One additional consideration is that the new subtype L does not appear to have spread much outside of central Africa, which suggests the virus is not especially aggressive or worrisome. Thus, while we take the mentioned warnings into account, we are not especially concerned about impact for people living with HIV in the UK and across Europe and the rest of the world. We nonetheless remain vigilant and will continue to monitor both the genetic variants of HIV in circulation and responses to treatment. Let's take this opportunity to celebrate the success of HIV treatment in the UK, where most diagnosed patients are on effective treatment, with full viral suppression so that there is no detectable level of virus in their blood and so no risk of transmission to others.

For further information please contact Jo Josh, British HIV Communications Officer at [email protected] or +44 (0) 7787 530922.