EPIDEMIOLOGIC CONTRAST BETWEEN, HIV AND H TLV RETROVIRUSES

There are interesting contrasts between the epidemiological characteri stics of the two subfamilies of human retroviruses. The oncoretrovirus HTLV-I and II are endemic in Intertropical Africa, North and South Am ericas and in the South of Japan. The lentiretroviruses HIV 1 and 2 ar e epidemic in the five continents and are progressing rapidly. The sex ual transmission is much more efficient for HIV than for HTLV. The mot her-to-child transmission occurs mostly by breast feeding for HTLV, wh ile it is perinatal for HIV. Concerning the cell-virus relationship, w hile the oncoretroviruses stimulate and eventually immortalize the T4 or T8 target cells, the lentiretroviruses are cytocidal for the T4 cel ls. The contrast extends to the latent period between primary infectio n and disease : much longer in a case of HTLV linked to either hematol ogical (ATL) or neurological (TSP/HAM) disorders than HIV linked to AI DS. Finally, prevention by vaccine should be achievable much earlier f or HTLVs than for HIVs.