Antiviral unit (AVU): reference services
Source: gov.uk (2025-10-13)

AVU provides services for genotypic antiviral resistance testing of HIV, HSV and HCV, investigation of HIV transmission events and HSV antiviral resistance testing by phenotyping.

Antiviral unit (AVU) houses a ‘World Health Organization global specialised HIV drug resistance laboratory’.

Services available

AVU provides reference services for:
- genotypic resistance testing of HIV (including minority mutant detection)
- analysis of HIV transmission events for public health-related investigations
- HIV subtyping and strain characterization by sequencing
- Hepatitis C virus (HCV) whole genome sequencing
- Herpes simplex virus (HSV) antiviral resistance testing by cell culture-based phenotyping and genotyping
The HCV whole genome sequencing service provides HCV genotyping and drug resistance analysis in a single test. Use request form S15 (https://www.gov.uk/government/publications/hcv-genotypic-susceptibility-testing-request-form) and contact the laboratory – contact details below (#contact) – if you require further information.

Other reference and training activities include:
- organisation of UK external quality assessment for genotypic HIV antiviral resistance testing
- provision of training in laboratory and clinical aspects of HIV antiviral resistance testing, especially implementation of new assays
- leading the UK HIV Resistance Network of NHS and PH labs that perform HIV genotypic antiviral resistance testing
Research and surveillance

AVU research and surveillance activities include:
- development and roll-out of novel genotypic assays for detection of drug resistance in HIV, HCV and HSV including whole genome sequencing
- development and application of single-cycle phenotypic assays for investigation of HIV drug resistance
- investigation of the role of accessory mutations in levels of HIV drug resistance and viral fitness
- surveillance of HIV transmitted drug resistance
- molecular epidemiology studies of HIV transmission and investigation of early events in HIV transmission
- coordination of the UK’s HIV Genomics Database in support of monitoring progress towards ending HIV transmission
For further information, see our guidance on how to submit proposals to access anonymised data from the UK’s HIV Genomics Database (https://www.gov.uk/guidance/uk-hiv-genomics-database).

Requesting tests

Use request forms S9 (https://www.gov.uk/government/publications/hiv-genotypic-susceptibility-testing-request-form), S15 (https://www.gov.uk/government/publications/hcv-genotypic-susceptibility-testing-request-form) and S4 (https://www.gov.uk/government/publications/herpes-simplex-virus-referral-form) when requesting HIV, HCV or HSV antiviral resistance tests, respectively.

For other tests, please contact the laboratory before submitting samples.

Please note: HSV type-specific serology testing is no longer available from UKHSA Colindale.

For intrathecal HSV antibody testing, please refer to the Immunisation and Diagnosis Unit (https://www.gov.uk/guidance/immunisation-and-diagnosis-unit-idu-diagnostic-and-reference-services) page.

AVU guidance and forms
- Antiviral resistance testing in the management of hepatitis C virus infection (https://www.gov.uk/government/publications/antiviral-resistance-testing-in-the-management-of-hepatitis-c)
- VRD user manual (https://www.gov.uk/government/publications/virus-reference-department-vrd-user-manual)
- HIV genotypic susceptibility testing request form (S9) (https://www.gov.uk/government/publications/hiv-genotypic-susceptibility-testing-request-form)
- Herpes Simplex Virus drug susceptibility request form (S4) (https://www.gov.uk/government/publications/herpes-simplex-virus-referral-form)
- HCV genotypic susceptibility testing request form (S15) (https://www.gov.uk/government/publications/hcv-genotypic-susceptibility-testing-request-form)
Contact AVU

Antiviral unit (AVU)

UK Health Security Agency61 Colindale AvenueLondonNW9 5EQ

Email xxx@xxx.xx (mailto:xxx@xxx.xx)

Telephone xx-xxxx-xxxx

DX address DX address UKHSA Colindale VRD, DX 6530006