Laboratory Diagnosis of Human T-cell Lymphotropic Viruses (HTLV) Infection, Diagnosis of HTLV-1 Infection

Laboratory_Diagnosis of Human T-cell Lymphotropic Viruses (HTLV) Infection

D. Laboratory_Diagnosis

Serology - Laboratory diagnosis rests mainly on the detection of antibodies against using screening EIAs. A passive particle agglutination assay (Serodia) is also available and is widely used in Japan for the screening of blood donations. Current EIAs cannot distinguish between HTLV-I and HTLV-II. However, a commercial Western blot using recombinant HTLV antigens are available which can distinguish between HTLV-I and HTLV-II. There appears to be some correlation between the titre of anti-HTLV-I antibody and the likelihood of developing ATL and TSP in HTVL-I carriers.
Detection of proviral DNA - PCR can also be used to detect HTLV from peripheral blood mononuclear cells and can distinguish between HTLV-1 and HTLV-II. There is also interest in quantitative PCR assays to quantify viral load since, as in the case of antibody titre, there appears to be correlation of high viral loads with the likelihood of developing ATL and TSP in HTLV-I carriers.

E. Management

There is a possibility that some of the agents currently in use against HIV, especially the nucleoside analogue inhibitors, may work against HTLV-1. However, since ATL and TSP present years following infection, there appears little justification in using antiviral therapy in healthy carriers. A combination of interferon-alpha and zidovudine had been reported to be effective in treating ATL patients. A combination of zidovudine, danazol, and Vitamin C in providing temporary relief for TSP patients.

F. Prevention

Screening of blood donations for HTLV-I is now routinely carried out in high prevalence areas such as Japan. However, there is a trend towards screening in low prevalence areas as well e.g. USA and France. In other low prevalence areas, screening is only carried out on donors who originate from high prevalence areas e.g. Japan and the Carribean. In Japan, antenatal screening for HTLV-1 antibody is carried out for pregnant wowen. Those who are positive are advised not to breastfeed their infants. Research is being carried out on the development of a vaccine against HTLV-I.