Impact case study database

Work lead by Leigh-Brown on the genetic diversity and spread of HIV has directly impacted health, policy and the law.

Sets of HIV mutations identified by the Leigh Brown’s group at Edinburgh were included in the Stanford HIV Drug Resistance Data base [5.1] and the UKHIV drug resistance database [5.2]. These are considered by clinicians to tailor the appropriate drug treatment for the individual, by public health officials monitoring HIV drug resistance, and also by pharmaceutical companies developing new drugs to fight HIV. This is important because, although anti-retroviral drugs are effective, HIV mutates at a high rate and can develop drug resistance. In people receiving treatment, this can lead to treatment failure, disease progression, and transmission to other untreated individuals. Leigh Brown also sits on the steering committee of the UK HIV Drug Resistance Database.

Public Health England and the U.S. Centre for Disease Control (CDC) use HIV sequence data to track transmission in populations, and it and the methods developed [3.5] form a cornerstone of “Ending the Epidemic – A Plan for America” [5.3].

Policy changes by the CDC and Public Health England

The US Centre for Disease Control (CDC) released the first version of “Detecting and Responding to HIV Transmission Clusters - A Guide for Health Departments” in 2016/17. This was updated in June 2018 [5.4]. Leigh Brown’s research describing the use of HIV-TRACE (TRAnsmission Cluster Engine Tool) is referenced in this document (Appendix G), and is referred to in a letter of support from the CDC’s Deputy Associate Director of Science [5.5]. The use of HIV sequence data to analyse characteristics of HIV transmission have now also been adopted by Public Health England (PHE), as referred to in a letter of support from PHE’s head of national HIV surveillance [5.6]. Specifically, the UKHIV Drug Resistance Database [5.2] is referenced in both the 2016 and 2017 PHE HIV annual reports [5.7i & ii], with Leigh Brown’s publication being referenced in the 2017 report. The 2017 report looks at the potential for the elimination of HIV transmission, AIDS and HIV-related deaths in the UK. This is a recent and welcome change [5.8]. Services to monitor transmission events, HIV transmitted drug resistance, the role of accessory mutations in levels of HIV drug resistance are some of the genome sequencing services offered by the Antiviral Unit, PHE.

State of the Union Address 2019

The power of HIV sequence analysis for tracking transmission, as shown by Leigh Brown’s work identifying hidden risk groups, has been explicitly recognised in “Ending the HIV Epidemic: A Plan for America”. This plan was highlighted in the State of the Union Address 2019 [5.3] as a critical tool for identifying accelerating outbreaks and guiding intervention.

Corroboration of HIV transmission by phylogenetic analysis is deemed essential in England, Wales and Scotland court cases according to Guidelines for prosecutors. Specifically, for cases where transmission has occurred, an expert will be required to give evidence that phylogenetic analysis of samples of the victim and accused produced a result consistent with transmission between the two individuals concerned. Therefore, identification of the accused as the source of the infection in cases of transmission must be corroborated.

England and Wales – The Crown Prosecution Service of England & Wales released Legal guidance on Intentional or Reckless Sexual Transmission of Infection in 2013 (outwith the REF impact period but in practice throughout the period [current CPS guidelines 5.9]. Leigh Brown’s phylogenetic research is referenced in a section of the guidelines which addresses the use of phylogenetic evidence where a defendant is accused of reckless transmission of the virus [5.10i]. The international campaign group HIV Justice Network ( https://www.hivjustice.net [5.10ii]) lists over 25 criminal cases in the UK involving HIV transmission from 2014-present. In one of these, a case in Coventry in 2015, the lack of phylogenetic evidence was specifically identified as a reason for a charge to be dropped [5.10iii].

Scotland - Crown Office and Procurator Fiscal Service (COPFS) guidance for prosecutors on the “Intentional or reckless sexual transmission of, or exposure to, infection”. These guidelines for prosecutors, produced in July 2014, state that it is essential to provide evidence showing that the victim contracted the infection from the accused [5.11]. The guidelines were drafted in conjunction with the National Aids Trust.

Leigh Brown’s body of research using phylogenetic analysis to show transmission patterns is the underlying research that this impact relies upon and the first prosecution of HIV transmission in the UK involved two individuals who had been recruited to, and had their virus sequenced in a research study he led. Subsequently he appeared as an expert witness in this case. He has in addition acted as expert witness in court cases in the UK and wider (Republic of Ireland [5.12] during REF period).

In 2018, Leigh Brown was called upon by the legal team acting for the defence in an Irish criminal case to discuss the significance of phylogenetic scientific evidence with the court. The Republic of Ireland was unusual in not routinely using phylogenetic evidence as a matter of course, as indeed it is now standard practice (England and Wales, and Scotland) for scientific evidence to be included in court proceedings: cases may be, and have been, dismissed by the judge where this evidence has been omitted. Scottish guidelines stipulate that scientific evidence is essential to support a case but cannot on its own convict.