Serological Differences between Human T‐lymphotropic Virus Type‐I (HTLV‐I) and HTLV‐III/LAV

Abstract

Sera from each of five preselected groups of patients with acquired immune deficiency syndrome (AIDS), AIDS‐related complex (ARC), hemophilia, adult T‐cell leukemia (ATL), and healthy controls were examined for antibodies to human T‐cell leukemia (T‐lymphotropic) virus type‐I (HTLV‐I) and HTLV‐III by indirect immunofluorescence (IF) and radioimmunoprecipitation (RIP) methods. All sera from five patients with AIDS, ARC, and hemophilia reacted at titers from 1: 512 to 1: 5,120 with fixed H9/HTLV‐III cells by IF but not with fixed MT‐1 cells carrying HTLV‐I. Similarly, sera from patients with AIDS, ARC, and hemophilia precipitated HTLV‐III‐specific polypeptides of 120K, 46K, and 24K. In contrast, sera from five patients with ATL did not react with fixed H9/HTLV‐III cells, but reacted with fixed MT‐1 cells. Moreover, HTLV‐I‐specific polypeptides of 68K, 28K, and 24K were precipitated with sera from ATL‐patients but not with anti‐HTLV‐III‐positive sera. Recently, we infected HTLV‐I‐carrying MT‐4 cells with HTLV‐III and provoked strong cytopathic effects. This system enabled testing for neutralizing antibodies to HTLV‐III. Neutralizing titers to HTLV‐III of five anti‐HTLV‐III‐positive sera ranged from 1:720 to 1:9,000. In contrast, all five seronegative controls showed no or only low reactivity to HTLV‐III envelope (1:80 and 100). However, three out of five anti‐HTLV‐I‐positive sera exhibited weak cross‐reactivities with HTLV‐III. The reactivities were expressed as <1:160, except for one case (1:720). They were considered to be nonspecific since they were negative for HTLV‐III antibodies in the radioimmunoprecipitation studies.

Evaluation of passive particle agglutination test for antibody to human immunodeficiency virus

“…All the specimens giving à particle agglutination titer of 105 or above were positive by immunofluorescence. Since all immunofluorescence-positive samples were radioimmunoprecipitation positive without exception, although not vice versa (6,20), we studied only five serum samples which were positive by particle agglutination but negative by immunofluorescence. Four of the five specimens with a particle agglutinationpositive but immunofluorescence-negative reaction were shown to contain the antibodies to env gene products gpl20 and gpl6O but not gag polypeptides p24 and pl9 of the virus by radioimmunoprecipitation.…”