BC-CfE responds to the discovery of a highly virulent variant of subtype-B HIV-1

posted on March 28, 2022

The BC-CfE has responded to a new study published in the journal Science reporting on the discovery of a highly virulent variant of HIV-1 found to be circulating in the Netherlands and other parts of western Europe during the past two decades. Referring to this variant as “virulent subtype B” HIV (VB), the Dutch researchers found that 109 individuals with this variant had up to a 5.5-fold higher viral load compared with 6,604 individuals with other subtype-B strains. Those with VB were also found to have a two-fold more rapid CD4 cell decline. A low CD4 count means HIV has weakened the immune system.

Without treatment, those living with the VB variant reached advanced HIV, defined as CD4 cell counts below 350 cells per cubic millimeter, with long-term clinical consequences, much quicker on average than those with other HIV variants.

A genetic sequence analysis carried out by the Dutch researchers suggests the VB variant arose in the 1990s due to a unique mutation, which came with increased transmissibility and an unfamiliar molecular mechanism of virulence.

The BC-CfE’s Assistant Laboratory Director, Chanson Brumme, Laboratory Director Zabrina Brumme, and Executive Director and Physician-in-Chief Dr. Julio Montaner responded to these findings in an eLetter titled, "Real-time surveillance for HIV-VB implemented in British Columbia, Canada", in which they describe how the BC-CfE quickly acted to investigate whether VB was present in BC and implement methods to monitor for its potential arrival.

Since 1998, the BC-CfE Laboratory has performed HIV drug resistance testing for all of BC and most of Canada. Because of this, the lab is well-positioned to monitor the potential introduction of VB in BC. BC-CfE researchers sought to detect VB through phylogenetic analysis of HIV sequences collected during routine HIV drug resistance testing from participants of the BC-CfE’s Drug Treatment Program (DTP).

The DTP is funded by BC’s provincial government, through its PharmaCare program, to distribute anti-HIV drugs and information from all participants is entered into a database. This provides data for clinical and virologic outcome evaluations of patients receiving antiretroviral therapy, and also acts as an "early warning system" to alert government about the trajectory of HIV/AIDS in the province.

Thankfully, the laboratory’s findings suggest VB has not yet arrived in our region. However, as the BC-CfE’s letter published in Science makes clear, timely identification of such cases is of critical importance due to the risk of rapid disease progression if VB is left untreated. The news of the variant also caused a quick policy change for the BC-CfE, as, within 24 hours, the BC-CfE had adapted existing quality-control procedures to screen all newly collected HIV sequences for VB in real time. The BC-CfE also enacted measures to immediately alert care providers to sequences that bear high similarity with VB to ensure prompt therapy initiation.

We encourage other HIV drug resistance testing laboratories worldwide to consider implementing similar measures. Such monitoring is essential to track the emergence of viral variants of concern and to quickly identify sources of increased individual, and population-level harms.
- Chanson Brumme

BC Centre for Excellence in HIV/AIDS

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BC-CfE responds to the discovery of a highly virulent variant of subtype-B HIV-1

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