Comparison and fine mapping of both high and low neutralizing monoclonal antibodies against the principal neutralization domain of HIV-1.

Monoclonal antibodies raised against viral lysate of HIV-1 (strain LAV-1) and against recombinant gp 160 of HIV-1 (strain HTLV IIIB) which neutralized HIV-1 in a type specific manner were mapped with the aid of peptides (Pepscan analysis). Each of these monoclonal antibodies bound to peptides located on the principal neutralizing domain (PND) of HIV-1. We found that the antigenic sites of the MAbs described in this paper are represented by linear peptides of at least 10 amino acids long. The affinity of the MAbs is high for these peptides and in the same order of magnitude as for native gp 160. The fine mapping of the epitopes may reflect structural features of the PND, for instance which amino acid side chains are exposed and which are buried in the protein. Furthermore the fine mapping of the epitopes explained the HIV type-specific neutralizing activity of the MAbs. Antibodies that bound to the tip of the loop (amino acids QRGPGRAF) have a higher neutralizing activity than antibodies that bound to amino acids towards the N-terminal side of the loop (amino acids KSIRI). Furthermore, MAbs that bound to virtually the same amino acids on the tip of the loop (amino acids IQRGPGRAF and RGPGRAFV) had different neutralizing activities due to different affinities for native gp 160. These data reveal that neutralizing activity not only is determined by the affinity of an antibody to the neutralizing site but also by its fine binding specificities to the V 3 loop of gp 120.

Effects of anti-gp120 monoclonal antibodies on CD4 receptor binding by the env protein of human immunodeficiency virus type 1.

Monoclonal antibodies (MAbs) to defined peptide epitopes on gp120 from human immunodeficiency virus type 1 were used to investigate the involvement of their epitopes in gp120 binding to the CD4 receptor. Recombinant vaccinia viruses were constructed that expressed either full-length gp120 (v-ED6), or a truncated gp120 lacking 44 amino acids at the carboxyl terminus (v-ED4). Binding of these glycoproteins to the CD4 receptor was detected directly with metabolically labeled gp120 or indirectly with the gp120 MAbs. Truncated gp120 from v-ED4 bound to CD4-positive cells less than 1/12 as well as gp120 from v-ED6, indicating that the C-terminal region of gp120, which is conserved in numerous isolates of human immunodeficiency virus type 1, is critical for CD4 binding. However, MAb 110-1, which recognizes a peptide contained in the region deleted from v-ED4 (amino acids 489 through 511), did not inhibit binding of gp120 to CD4. MAb 110-1 also reacted with gp120 bound to the CD4 receptor, indicating that the epitope for this antibody does not directly interact with CD4. A second MAb, 110-4, which recognizes a peptide epitope located between amino acids 303 and 323 and has potent viral neutralizing activity, also bound to gp120 on the CD4 receptor. Furthermore, pretreatment of gp120 with MAb 110-4 at concentrations approximately 1,000-fold higher than those required for complete virus neutralization inhibited subsequent CD4 binding by only about 65%. Taken together, these data suggest that neutralization mediated by antibody 110-4 does not result from binding of this MAb to the CD4-binding site of gp120.

Humoral and cellular immunity to varicella-zoster virus glycoprotein gpI and to a non-glycosylated protein, p170, in the strain 2 guinea-pig.

Strain 2 guinea-pigs were inoculated with infectious varicella-zoster virus (VZV) or with immunoaffinity-purified proteins of VZV. Monoclonal antibodies to the VZV gpI (90,000/58,000 complex) and to a non-glycosylated protein, p170, were used to prepare the polypeptide antigens. Humoral and cell-mediated immune responses to the infectious virus were compared with those elicited by the gpI and p170 proteins. Both VZV IgG antibody production and T lymphocyte proliferation to VZV were detected after immunization with infectious VZV and with VZV proteins. The antibody and T lymphocyte responses waned after protein immunization in comparison with the responses induced by infectious VZV but were detected again immediately after reimmunization with gpI or p170.

Immunity to varicella-zoster viral glycoproteins, gp I (gp 90/58) and gp III (gp 118), and to a nonglycosylated protein, p 170.

Humoral and cellular immunity against two major glycoproteins (gp) of varicella-zoster virus (VZV), gp I (gp 90/58) and gp III (gp 118), and against a nonglycosylated phosphoprotein (p 170) was demonstrated in human subjects. Primary VZV infection was accompanied by the development of IgG to gp I (mean titer 1:200), gp III (mean titer 1:132), and p 170 (mean titer 1:331). Increased IgG antibody production to each of the VZV proteins occurred during recurrent VZV infection with mean titers to gp I of 1:29512, to gp III of 1:15848, and to p 170 of 1:15848. Persistent high titers to gp III (mean titer 1:891) and to p 170 (mean titer 1:2238) were observed in 75% and 88% of VZV-immune subjects, respectively. T lymphocytes which proliferated on stimulation with gp I, gp III, and p 170 developed with primary VZV infection. VZV-immune subjects had mean transformation indices of 4.2 +/- 0.70 SE to gp I, 4.7 +/- 1 SE to gp III, and 3 +/- 0.39 SE to p 170. Among individual subjects, humoral and cellular immunity was not always detected to all three of the VZV proteins. Resolution of primary VZV infection and maintenance of VZV latency did not require a host response to each of these major viral proteins.

Varicella-zoster virus infection of human sensory neurons.

Primary varicella-zoster virus (VZV) infection of humans may result in latent infection of sensory neurons in the peripheral nervous system. To examine the interaction of VZV with the sensory neuron we infected immunochemically defined human neurons with cell-associated VZV. Utilizing double-label immunofluorescence technology, a VZV-specific glycoprotein and a nonglycosylated phosphoprotein were detected in human fetus dorsal root ganglion (DRG) neurons, as defined by the presence of the neuron-specific enolase isoenzyme and the A2B5 ganglioside antigen, respectively. In addition to VZV antigen expression, progressive virus-induced cytopathic damage (neuronal enlargement and nuclear granulation of a fraction of the neuron population) was evident. As determined by transmission electron microscopy, VZV-infected human fetus DRG neurons contained empty and complete nucleocapsids with numerous pleomorphic virus particles in the cytoplasm, often in association with vacuoles. Although virus-specific antigen expression, particle synthesis, and cytopathic effects were observed in the human neuron population, neurons were less susceptible to VZV-induced cytopathic damage than supporting nonneuronal cells, suggesting neuronal modulation of VZV infection in vitro. This system provides the first model to examine the neuron- and virus-specific gene(s) and gene product(s) pertinent to the interaction of VZV with the human neuron.

Cytologic manifestations of cervical and vaginal infections. II. Confirmation of Chlamydia trachomatis infection by direct immunofluorescence using monoclonal antibodies.

We found inflammatory patterns of transparent lymphocytes on increased numbers of histiocytes suggestive of chlamydial infection in 68 (56%) of 121 cervical cytologic smears. Chlamydia trachomatis was isolated from 36 (53%) of those with and only two (4%) of those without such inflammatory patterns. Direct stain with fluorescein-conjugated monoclonal antibodies demonstrated elementary bodies of C trachomatis in 30 (79%) of the 38 culture-positive patients, including 29 of the culture-positive patients who had an inflammatory cytologic pattern suggestive of C trachomatis infection. Thus, Papanicolaou smears can be screened for inflammatory pattern, and separate endocervical smears from patients with a pattern suggestive of chlamydial infection can then be stained by immunofluorescence to confirm the presence of C trachomatis infection. This two-step approach detected 29 of 38 infections confirmed by culture in the present study, giving a sensitivity of 76%, a specificity of 100%, and a positive predictive value of 100% in a population having a 31% prevalence of C trachomatis infection.

Specific thymus-derived (T) cell recognition of papova virus-transformed cells.

As a first step toward identifying papova virus-specific transplantation antigens and characterizing the immune response to these antigens, a series of congenic B10 mouse lines transformed by polyoma virus and SV40 has been obtained. B10.D2 (H-2d) mice immunized with x-irradiated polyoma-transformed B10.D2 cells (PyB10.D2) contained within their spleens a population of T cells that upon restimulation in vitro preferentially lyse 51Cr-labeled PyB10.D2 compared with other allogeneic polyoma-transformed target cells or SV40-transformed B10.D2 cells. Twenty hours after acute infection with polyoma virus, SV10.D2 cells express cell surface structures recognizable by polyoma-specific CTL. This CTL activity is therefore both polyoma specific and H-2 restricted, indicating associative recognition of H-2 molecules along with the virus-specific antigen.