Humoral responses to linear epitopes on the HIV-1 envelope in seropositive volunteers after vaccine therapy with rgp160.

Humoral responses to the HIV-1 envelope were investigated in 30 human volunteers enrolled in a phase I vaccine therapy trial of rgp160 (LAI/LAV) using two techniques that emphasize detection of antibody response against linear (continuous) epitopes: immunoblotting and PEPSCAN. Seven fusion proteins containing large portions from constant regions 1, 2, 3, and 5, and variable region 3 of gp120 and two regions in the transmembrane protein, gp41, were employed in immunoblots to quantitatively measure immune response as a function of immunization. In addition, the entire gp160 (LAI/LAV) envelope protein was constructed in duplicate sets of 211 overlapping 12-mer peptides to fine-map the changes. Immunoblotting defined significant changes in reactivity to epitopes in constant regions; of 28 volunteers completing the trial, the percentage with reactivity against C1 changed from 62 to 100%; for C2, from 0 to 46%; for C3, from 0 to 82%; and for a constant region in gp41, from 25 to 68%. PEPSCAN on a subset (n = 8) of these volunteers identified new reactivity to epitopes throughout the envelope, concentrated in V1, C3, and C5 in gp120 and several peptides in gp41. Completely immunized patients responded to double the number of linear epitopes compared with two patients receiving alum alone. The results verify that the response to rgp160 is significantly broadened after immunization, providing additional evidence that HIV-1-infected volunteers can expand their antibody repertoire against a protein from a pathogen during chronic infection with that same pathogen. These results expand those previously obtained in this patient cohort, by defining explicitly the immunogenic regions recognized postvaccination and by providing methodology for quantitating those changes.

Immunohistochemical demonstration of differential substance P-, met-enkephalin-, and glutamic-acid-decarboxylase-containing cell body and axon distributions in the corpus striatum of the cat.

The immunohistochemical localization of neuronal cell bodies and axons reactive for substance P (SP) and methionine-enkephalin (ME) was investigated in the corpus striatum of the adult cat brain and compared with that of glutamate decarboxylase (GAD), synthetic enzyme for gamma-aminobutyric acid. Striatal cell bodies reactive for ME could be identified only in colchicine treated cats, are medium size, ovoid striatal cells, and are found in large numbers in a more or less even distribution throughout the caudate nucleus, putamen, and nucleus accumbens. The striatal region most densely occupied by ME-immunoreactive cells is the ventral and central part of the caudate head. Modest numbers of larger ME-reactive neurons are dispersed throughout the entopeduncular nucleus and the pars reticulata of the substantia nigra. Striatal cells of medium size reactive for SP could be identified, with or without colchicine, in largest numbers in the medial half of the caudal three-fourths of the putamen and in clusters of irregular size and shape in the head of the caudate nucleus. Cells reactive for SP are also common in layer II and the islands of Calleja of the olfactory tubercle. We could not reliably visualize GAD-positive cell bodies in the striatum, even with colchicine treatment; however, they could be seen readily in all pallidal structures such as the globus pallidus, ventral pallidum, entopeduncular nucleus, and substantia nigra. Axons reactive for ME are found mainly in the globus pallidus where they form a dense and even network throughout the nucleus. The globus pallidus is almost devoid of SP reactivity except near its extreme caudal pole. Conversely, SP-immunoreactive axons form dense meshworks in the entopeduncular nucleus and substantia nigra where ME immunoreactivity is minimal. Fewer, but still ample numbers, of SP-reactive axons are present also in the ventral tegmental and retrorubral areas of the midbrain tegmentum and in the ventral pallidum of the basal forebrain, but only sparse ME-reactive axons are present in these areas. This differential distribution of SP- and ME-containing axons in the pallidal and nigral structures stands in contrast to the relatively homogeneous and dense distribution of GAD-containing axons throughout the dorsal and ventral pallidum, entopeduncular nucleus, and substantia nigra.(ABSTRACT TRUNCATED AT 400 WORDS)