W. J. A. Krone

Distinct IgG recognition patterns during progression of subclinical and clinical infection with lymphadenopathy associated virus/human T lymphotropic virus

Longitudinal IgG recognition patterns of viral proteins were studied in 15 men who had seroconverted for lymphadenopathy associated virus/human T lymphotropic virus (LAV/HTLV-III). Antibodies to the major viral core protein p24, which is a cleavage product of the gag gene encoded precursor protein pr55, appeared first. These were soon followed by antibodies to pr55 and more gradually by antibodies to the other gag gene encoded cleavage product p18, the env gene encoded transmembrane glycoprotein gp41, the env gene encoded glycoproteins gp65 and gp110, and the putative pol gene product p33. In 13 subjects who remained healthy the reactivity to the different proteins increased or stabilised with time, while in two men who developed acquired immune deficiency syndrome (AIDS) the reactivity, most noticeably to gag encoded proteins, diminished before or at the onset of symptoms.

Pathogenesis of HIV and its implications for serodiagnosis and monitoring of antiviral therapy

Human immunodeficiency virus (HIV) is lymphotropic and neurotropic. In vivo clinical and immunological abnormalities develop in a large proportion of long-term HIV antibody seropositive persons. Different stages of HIV infection are marked by expression of HIV genes, production of HIV antibodies, formation of antigen/antibody complexes and clearance of such complexes. Transient HIV antigenemia appearing generally 6-8 wk prior to HIV antibody (HIV-Ab) seroconversion and lasting 3-4 mth is generally seen in acute infection. IgM antibodies predominantly to core proteins may occasionally be detectable when, or just before, IgG antibodies appear. If IgG antibodies to both envelope and core proteins persist in the absence of HIV-Ag the short-term prognosis is relatively good. However, HIV-Ag seroconversion may appear at any time after HIV-Ab seroconversion. Progression to AIDS is strongly associated with declining or absent levels of IgG antibodies to p24. IgG2 and IgG4 antibodies to HIV, which are mainly directed to p24, disappear most dramatically. Titers of antibodies to HIV p24 below 64 are strongly associated with the presence of HIV antigen and a poor clinical outcome. HIV antigen was detected frequently in sera from children in all stages of infection in contrast to adults whose sera were generally HIV-Ag negative when asymptomatic and positive when AIDS was apparent. HIV antigen may be less efficiently detected with the present assays in sera from regions where the prototype strains of HIV (HTLV-III and LAV) are less prevalent, like Central Africa. Persistence of HIV-Ag in cerebrospinal fluid (CSF) appears to be pathognomonic for progressive encephalopathy, particularly in children. Levels of HIV-Ag in serum, and possibly in CSF, can be decreased by nucleoside analogues, such as AZT. This indicates HIV-Ag and possibly antibody to HIV core protein p24 as suitable markers for selecting individuals for antiviral therapy as well as monitoring the efficacy of such therapy.

Detection and characterization of HIV-1 by polymerase chain reaction.

Recently a new technique, the polymerase chain reaction (PCR), has been used for the detection and characterization of HIV-1 proviral DNA and viral RN A. These reports support the notion that the PCR is more sensitive and specific than other established HIV-1 detection techniques. However, due to its extreme sensitivity, the PCR is highly susceptible to contamination, resulting in false positive results. To avoid contamination, strict rules on sample preparation and pre- and post-PCR handling are required. Confirmation of both positive and negative PCR results by independent techniques is not always feasible, and, therefore, optimal PCR conditions, inclusion of control samples, repetition of results, and confirmation of specificity by hybridization are required. The choice of the material from which HIV-1 is amplified, the primers used for amplification as well as the PCR conditions will determine what is actually amplified.

Introduction of lymphadenopathy associated virus or human T lymphotropic virus (LAV/HTLV-III) into the male homosexual community in Amsterdam.

To establish when lymphadenopathy associated virus or human T lymphotropic virus (LAV/HTLV-III) was introduced into the Netherlands, we studied a cohort of homosexual men who participated in a hepatitis B vaccine efficacy study between 1980 and 1982. On entry into the study (November 1980 to December 1981) five (0.7%) out of 685 participants were found to have antibodies to LAV/HTLV-III, and during follow up 15 seroconversions were detected among the 680 who had been seronegative initially (end point attack rate 3%). LAV/HTLV-III was not transmitted by the heat inactivated hepatitis B virus (HBV) vaccine used. Anal sexual contact and antibodies to cytomegalovirus (CMV) were found to correlate with seropositivity or seroconversion for LAV/HTLV-III. Six out of 15 men who seroconverted reported a mononucleosis like illness, but three of them had other concurrent virus infections. To date, only one of the 20 seropositive men has developed the acquired immune deficiency syndrome (AIDS), three years after his seroconversion. This study shows that the introduction of LAV/HTLV-III into the Dutch male homosexual community took place at the end of the 1970s, a few years before the first case of AIDS in a native Dutchman.

Characterization of the African HIV-1 isolate CBL-4 (RUT) by partial sequence analysis and virus neutralization with peptide antibody and antisense phosphate-methylated DNA.

The HIV-1 isolate CBL-4 (RUT), originating from Tanzania, was characterized using a comprehensive virus-typing system. This system included sequence analysis of the region coding for the neutralization domain in the third variable region (V3) of the external envelope and of the tat responsive (TAR) region after polymerase chain reaction (PCR) amplification of these sequences from cellular DNA in the CBL-4 (RUT) producer line. Based on independent cluster analysis of TAR and V3 sequences the CBL-4 (RUT) virus was positioned closest to the Z6 (and ELI) African virus family. The V3 amino acid sequence on the surface of the virus particle was confirmed by the inhibition of neutralization of CBL-4 (RUT) by a synthetic peptide derived from the nucleic acid sequence. Using antisense phosphate-methylated DNA covering the TAR loop region of LAV-1/HTLV-IIIB, inhibition of HTLV-IIIB and HTLV-IIIRF infection was seen, whereas no inhibition was observed for CBL-4 (RUT), indicating two or more mismatches in the TAR loop region, a characteristic shared with Z6 virus, but not with ELI. We propose a virus-typing system based on sequence analysis confirmed by virus neutralization with a peptide binding antibody and inhibition by antisense phosphate-methylated DNA to group viruses for laboratory use and vaccine design.