Human retrovirology

Abstract

Shortly after joining St. Mary’s Hospital Medical School in 1992 I started two major initiatives: 1) the HTLV European Research Network (HERN) (with Professors Weiss, de The, Weber, Chieco-Bianchi and Bertazonni); 2) A research clinic for patients with HTLV-1 infection with an accompanying study of the Natural History of HTLV-1 infection. In 1995 I established one of the first multi-disciplinary HIV/ante-natal clinics in the UK. These clinics continue to underpin my research, selections of which I present below for consideration of the degree of Doctor of Science. I start with the serological and clinical epidemiology that I initially conducted with and through HERN.

HTLV-1 Epidemiology

In 1994, our knowledge of European HTLV epidemiology comprised of many small, seroprevalence studies, spanning a decade or more, that had utilised a wide range of assays of variable sensitivity and specificity, and had been conducted amongst populations of differing perceived risk. In recognition of this we established the HERN criteria for the diagnosis of HTLV infections for sero-prevalence studies (1996; HERN*) and a panel of sera for quality control. Prior to initiating the definitive study of HTLV-1 infection among pregnant women in Western Europe we determined the reliability of the testing of pooled sera for HTLV-1 and -2 infections (2001; Andersson). I collated published and previously unpublished data from the network and in accordance with our criteria reported the seroprevalence of HTLV infections within the, then, boundaries of the European Union (1996; HERN, 1999; Taylor). We demonstrated that HTLV-1 and HTLV-2 sero-prevalence varied widely by geography and risk group. The most widely tested group, blood donors, had the lowest prevalence (0 < 3/10,000 donors), pregnant women were at intermediate risk, and injecting drug users and patients with sexually transmitted infections had the highest seroprevalence (0 < 6.5%). I then coordinated the HERN International Antenatal Study of 250,000 pregnant women in Belgium, France, Germany, Italy, Portugal, Spain and UK which demonstrated a 10 fold higher prevalence of HTLV infections amongst pregnant women in these countries compared with blood donors in the same regions, even though the prevalence varied (2005; Taylor*). In the UK arm we conducted a linked anonymised study and could therefore further characterise the risk of being HTLV-1 or HTLV-2 positive. As might be expected, pregnant women born in regions where HTLV-1 is endemic had the highest prevalence rates (1.7%), however, such selective screening would have only identified 32% of the infected women (2000; Ades). The HTLV antenatal seroprevalence data remains the defining study of HTLV infections in Western Europe and the comparator for any future assessment. In addition in the UK I used the existing reporting system to describe the incidence of diagnosed HTLV-associated disease in the UK during 1994 -1999 and triangulated these data, with census and the ante-natal seroprevalence data to estimate 20 – 30,000 prevalent HTLV infections in the UK (2000; Tosswill). In 2009, I revisited the epidemiology of HTLV, examining the data on which the much-cited estimate of 10 – 20 million persons infected worldwide was based and then having reviewed all published studies based on unselected general populations concluded that there are very few robust data on which to base any current estimate of HTLV seroprevalence (2009; Hlela).