Detection of HIV envelope specific antibodies by immunoelectron microscopy and correlation with antibody titer and virus neutralizing activity

Factor VIII, HIV and AIDS in haemophiliacs: an analysis of their relationship

In this review, the association between the Acquired Immune Deficiency Syndrome (AIDS) and haemophilia has been carefully examined, especially the data that have been interpreted as indicating transmission of the human immunodeficiency virus (HIV) to the recipients of purportedly contaminated factor VIII preparations. In our view, the published data do not prove the hypothesis that such transmission occurs, and therefore HIV cannot account for AIDS in haemophiliacs.

A morphological and immunolabelling study of freeze-substituted human and simian immunodeficiency viruses

Rapid freezing, freeze substitution and low temperature embedding were used to obtain resin-embedded specimens of HIV and SIV for morphological and immunolabelling studies, with particular emphasis on the 'lateral bodies' and p6 protein. HIV- or SIV-infected cells were fixed in 3% paraformaldehyde and cryoprotected with 0.5 M sucrose. Cells were applied to pieces of Whatman No 1 filter paper and impact-frozen onto a liquid nitrogen cooled copper block. Specimens were freeze-substituted at -90 degrees C using one of three different media: (a) absolute methanol, (b) methanol containing 0.5% uranyl acetate, and (c) methanol containing glutaraldehyde, osmium tetroxide and uranyl acetate. Specimens substituted in methanol and uranyl acetate showed both good structural preservation and retention of antigenicity. We found that the use of filter paper for supporting the specimen was an important factor in obtaining good freezing rates and was more practical than freezing mixtures of cells and gelatin. When compared with specimens prepared by conventional fixation and embedding, freeze-substituted virus particles showed a greater uniformity of shape and size and were more dense in appearance. Distinct 'lateral bodies' were not observed in freeze-substituted viruses. The viral protein p6 was widely distributed in the centre of mature virus particles.

Is a positive western blot proof of HIV infection?

It is currently accepted that a positive Western blot (WB) HIV antibody test is synonymous with HIV infection and the attendant risk of developing AIDS. In this communication we present a critical evaluation of the presently available data on HIV isolation and antibody testing. This evidence indicates that: (1) the antibody tests are not standardized; (2) the antibody tests are not reproducible; (3) the WB proteins (bands) which are considered to be encoded by the HIV genome and to be specific to HIV may not be encoded by the HIV genome and may in fact represent normal cellular proteins; (4) even if the proteins are specific to HIV, because no gold standard has been used to determine specificity, a positive WB may represent nothing more than cross-reactivity with non-HIV antibodies present in AIDS patients and those at risk. We conclude that the use of antibody tests as a diagnostic and epidemiological tool for HIV infection needs to be reappraised.

Detection of p24 in HIV-1 infected cells embedded in LR White and Lowicryl K4M

In this study we present a postembedding on-grid immunogold labelling procedure for the ultrastructural localization of the HIV-1 core protein p24. HIV-1 infected cells were fixed in 0.1% glutaraldehyde, incompletely dehydrated and embedded in LR White or in Lowicryl K4M. Antigenic sites were detected by incubation of ultrathin sections with primary mouse monoclonal antibody anti-HIV-1 p24, followed by the secondary antibody goat anti-mouse IgG coupled to 10nm gold particles. Antigenicity of p24 was found to withstand the applied fixation and was shown to be preserved in LR White as well as in Lowicryl. The described procedure permits the uncomplicated and easy detection of p24 in HIV-1 infected cells and tissues.

Interactive laser cytometric analysis of retroviral protein expression in HIV-infected lymphocytic cell lines

We have used interactive laser cytometry to investigate the expression of human immunodeficiency virus (HIV) envelope glycoproteins gp160, gp41, gp120, and the core protein p24 in the HIV-infected human lymphocyte cell lines H-9, CEM-SS, and C8166. This method allowed for the ultrasensitive detection of fluorescence signals at the single cell level and, when combined with specific anti-HIV antibodies, permitted unique quantitative detection of HIV antigens. Indirect immunofluorescence assays with monoclonal antibodies directed against gp120 revealed that a large proportion of lymphocytic cells expressed increased gp120-associated fluorescence consistent with HTLV-IIIRF infection. Certain monoclonal and polyclonal antibodies were also effective in quantifying gp160, gp41, and p24 expression. Expression of these antigens was found to vary significantly within 48 h. Significant loss (greater than or equal to 50%) of gp120 expression was observed when cells were treated with 1.0 microM AZT. The expression of the HIV-associated protein markers gp160, gp41, and p24 was detectable 24 h after infection of C8166, a cord blood lymphocytic cell line. C8166 cells expressed an additional 6- to 10-fold increase in gp120 in 48 h as well as a 3- to 4-fold increase in gp160, gp41, and p24. AZT (0.01 and 0.1 microM) decreased the expression of gp120, gp160, and p24 in a dose-dependent fashion. This new application of interactive laser cytometry permits early, sensitive, and statistically based distinctions in the expression of HIV-associated antigens in infected target cells at the single-cell level, and allows detection of important changes in HIV-associated antigen expression and the kinectics thereof.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection by immunogold techniques of HIV antigens in Lowicryl ultrathin sections of infected cells

A post-embedding technique for immunocytochemical analysis at the ultrastructural level was used to detect and localize HIV antigens on ultrathin sections of Lowicryl K4M-embedded HIV-infected cells. With serum from an AIDS patient, specific immunogold labelling was obtained exclusively on mature viral extracellular structures. The more intense reactivity was obtained with core antigens. The present immunoelectron microscopy method provides several advantages - high sensitivity of immunodetection, good preservation of cellular morphology, easy preparation procedure - which could lead to the use of this method for HIV-infected human tissues.

Morphogenesis and morphology of HIV. Structure-function relations

Fine structure and antigenic make-up analysis of HIV were combined in a 2D model, from which functional aspects can be deduced. On the envelope 72 probably trimeric surface knobs (gp120) are connected to the virion via the transmembrane protein gp41. Gp120 is shed during ageing of the virion, but host cell antigens stay firmly anchored to the envelope. Underneath the envelope, p17 forms the matrix protein layer, while the capsid of the double cone shaped core is built up of p24. The relation between biochemical findings and morphogenesis and maturation of HIV as well as aspects of pathogenesis and vaccination are discussed.

Expression of HIV antigens at the surface of infected T4 cells: immunoelectron microscopic evidence of an immunogenic phase prior to the viral release

HIV antigens were detected by immunoelectron microscopy at the surface of human and simian T4 lymphocytes that had been infected in vitro. HIV antigens were detected at the surface of cells exhibiting viral particles but also at the surface of cells before the release of virions. The latter cells may be considered immunogenic since they are capable of triggering specific immune responses without the cytopathic effects due to viral release.

The morphology of human immunodeficiency virus (HIV) by negative staining

We have examined preparations of human immunodeficiency virus 1 (HIV-1) and HIV-2 by negative staining electron microscopy. HIV-2 cultures contained large numbers of 130-200 nm particles containing a 130-nm-long by 30-70 nm-wide core. This core is probably of conical or pear-shaped morphology. Some particles exhibited a short fringe that could be seen to comprise a regular arrangement of repeating subunits when visualised end on. Identical particles were found in HIV-1 cultures but in much lower numbers. Attempts to carry out negative staining immune EM were unsuccessful. Also detected in both HIV-1 and HIV-2 cultures were small (70-80 nm) fringed viruslike particles. The possible significance of these particles is discussed.