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J V Torres

Publications and source records attributed to J V Torres.

52 records · Page 3Linked to original sources
PubMed1991

Neutralization epitope in the envelope glycoprotein of simian retrovirus-1 (SRV-1) and identification of the virus receptor.

We previously demonstrated that the area encompassing residues 147-162 of the envelope protein of simian retrovirus serotype-1 (SRV-1) is the target for rhesus anti-SRV-1 neutralizing antibodies. A peptide representing amino acids 142-167 of envelope protein (gp70) is capable of inducing virus-neutralizing antibodies in mice. The virus receptor was immunoprecipitated from Raji cells using gp70 as the ligand. Antibodies to peptide 142-167 inhibit the immunoprecipitation, indicating that the receptor recognizes residues 142-167 of the viral envelope protein.

Amino Acid Sequence↗
PubMed1990

Synthetic peptides of envelope proteins of two different strains of simian AIDS retrovirus (SRV-1 and SRV-2) represent unique antigenic determinants for serum neutralizing antibodies.

There are at least three distinct serotypes of simian type D retrovirus (SRV) which exhibit extensive serological cross-reactivity, but no cross-reactivity exists at the level of serum neutralizing antibodies. Amino acid sequence analysis and hydrophobicity plots of SRV-1 and SRV-2 envelope proteins were compared in order to identify unique potential antigenic determinants to which respective neutralizing antibodies may be directed. Peptides representing residues 147-162 of SRV-1 and 96-102 of SRV-2 were synthesized and assessed for their immunoreactivity. Free peptide inhibition of strain-specific serum (rhesus) neutralizing antibodies to SRV-1 and SRV-2 was demonstrated using the SRV-1 147-162 peptide and the SRV-2 peptide, 96-102, respectively. Inhibition of serum neutralizing activity by these peptides was also strain-specific, showing no cross-inhibition. SRV-1 147-162 conjugated to a protein carrier and cross-linked to Sepharose beads specifically adsorbed neutralizing antibodies from SRV-1 immune rhesus sera. The antibodies eluted from the immunoadsorbent possessed SRV-1 neutralizing activity, but showed no effect on the infectivity of SRV-2. Peptide SRV-1 147-162 also exhibited the capacity to bind specifically with a mouse monoclonal antibody which neutralizes the infectivity of SRV-1. Mice immunized with a recombinant SRV-1 envelope protein or with whole, inactivated SRV-1 produced antibodies which bound the SRV-1 147-162 conjugate, but not the protein carrier itself. Mouse antibodies to the SRV-1 147-162 conjugate exhibited specific binding with both native SRV-1 and with recombinant SRV-1 envelope protein. These findings provide strong evidence that SRV-1 147-162 and SRV-2 96-102 constitute at least two unique antigenic determinants, or parts thereof, which participate in the strain-specific neutralizing antibody response. Moreover, the findings indicate that the SRV-1 neutralizing antibodies produced by monkeys and at least a certain population of neutralizing antibodies produced by mice recognize the same epitope of SRV-1.

Amino Acid Sequence↗
PubMed1989

Cytotoxic and helper T-lymphocyte responses to antibody recognition regions on influenza virus hemagglutinin.

We have previously localized and synthesized twelve antibody recognition sites on influenza virus hemagglutinin (HA). These peptides correspond to exposed surface areas in the 3-D structure of HA. Using intact X31 virus as the immunogen, we have determined the recognition of these synthetic peptides by proliferative T-helper lymphocytes (ThL), delayed type hypersensitivity (DTH), and cytotoxic T-lymphocytes (CTL) responses. The responses to the individual determinants in each of these immune compartments were under separate Ir gene control. Conversely, using the peptides as immunogens, we have determined the ability of various peptide-specific antibodies (in outbred mice) and ThLs (in H-2k, H-2d, H-2s and H-2b mice) to recognize intact virus. Whereas most of the peptides primed the mice for an anti-peptide proliferative ThL response, only very few of these cross-reacted with the virus. The identity of the peptide(s) eliciting virus cross-reactive ThLs varied with the strain. The importance of antibody, ThL, CTL and DTH responses in protection against viral infection and in vaccine design is discussed.

Animals↗
PubMed1988

Cytotoxic T lymphocyte recognition sites on influenza virus hemagglutinin.

When influenza virus infection occurs, part of the cytotoxic T lymphocyte responses induced are directed to the major surface molecule of the virus, the hemagglutinin. However, despite their potential use as a peptide vaccine, little information is available concerning the submolecular areas in the hemagglutinin that are responsible for its immunologic recognition by cytotoxic T lymphocytes. The primary goal of this study is to determine whether submolecular areas recognized by antibodies and helper T cells are also important in the virus-specific, T lymphocyte-mediated cytotoxic responses generated towards virus-infected cells. A panel of synthetic peptides representing areas of the hemagglutinin, homologous to those in influenza AX-31 virus which have previously been shown to bind anti-influenza virus antibodies and provoke proliferation of virus-primed T-helper lymphocytes, was tested in two different cytotoxicity assays. In the experiments presented here, it was found that when selected peptides were incubated with appropriate L929 target cells, lysis by virus-specific cytotoxic T cells was observed. In addition, AX-31-primed lymphocytes preincubated with these synthetic peptides (both individually and as an equimolar mixture) exhibited enhanced lysis of virus-infected syngeneic targets. The cytotoxic responses showed dose-response characteristics in all cases, and in each of the two assays used the same patterns of cytotoxic induction were observed. The recognition of peptides was MHC-restricted since virus-specific cytotoxic T cells from C3H/He mice (H-2k) lysed L929 (H-2k) target cells after incubation with peptides or viruses, but did not lyse P815 (H-2d) targets under the same conditions.

Animals↗
PubMed1987

Antigenic regions on the beta chain of human chorionic gonadotropin and development of hormone specific antibodies.

Five peptides corresponding to four regions of the beta chain of human chorionic gonadotropin (hCG), were synthesized, purified and characterized. The four regions studied were selected on the basis of sequence differences between the beta chain of hCG (beta hCG) and the beta chains of related hormones. The peptides were found to bind rabbit and mouse anti-hCG antibodies as well as rabbit anti-beta chain antibodies, but did not bind antibodies against the alpha chain or against other hormones. All the peptides, even in their free form, were able to elicit high titer antisera in both rabbits and mice. In all cases, anti-peptide antisera bound to the immunizing peptide as well as to the native hCG and the isolated beta chain. These anti-peptide antisera did not bind to unrelated peptides, the alpha chain of hCG or to other hormones with very similar beta chains such as human luteotropic hormone (hLH), ovine luteotropic hormone (oLH) and equine chorionic gonadotropin (eCG). Since the areas represented by these peptides elicit antibodies that are specific for human beta hCG, they can formulate the basis for the development of discriminatory reagents for the beta chain of hCG.

Antibody Specificity↗
PubMed1983

Long-acting contraceptive agents: esters of norethisterone with alpha- and/or beta-chain branching.

The synthesis of eighteen esters of norethisterone (17 alpha-ethynyl-17 beta-hydroxyestr-4-en-3-one) is described. These all possess some form of alpha- and/or beta-substitution in the ester side-chain. The work was undertaken in order to evaluate any long-acting fertility control effect intrinsic in such compounds. A pentamethyl disiloxy ether was also included in the group of substances prepared for testing because of its similar substitution pattern.

Esters↗
PubMed1975

Genetic control of sterol esterification in developing wheat endosperm.

1. The action of gene Pln, previously characterized by the sterol ester patterns of mature whole wheat kernels, has been found to be restricted to the endosperm and not to affect the embryo, the pericarp or the seed coat. 2. The dominant allele Pln, which determines a sterol ester pattern with palmitate as the main ester, is also responsible for a low level of free sterol at maturity. A high level of free sterol is associated with the recessive allelet pln, which determines an ester pattern with linoleate as the main ester. 3. Divergence between the two phenotypes starts at about 21 days after anthesis, when cell proliferation has been completed, the aleurone layer has differentiated, and only cell enlargement is taking place. A marked increased in esterification, mainly by palmitate, which is controlled by the dominant allele, is concomitant with a sharp decrease in free sterol. 4. The increased net esterification is non-specific with respect to 4-demethyl sterols, because it affects the four main ones, namely sitosterol, stigmasterol, campesterol and cholesterol.

Alleles↗
PubMedDate not supplied

Characterization of T cell epitopes on the envelope glycoprotein of simian retrovirus 1 and 2 (SRV-1 and SRV-2) in several mouse strains.

Various mouse strains were immunized with either SRV-1 or SRV-2 virus adsorbed on alum. Seven to 14 days later spleen cells were removed, and spleen cells were cultured with varying amounts of SRV-1 virus and SRV-2 virus, or varying amounts of selected SRV-1 and SRV-2 synthetic envelope peptides to determine their ability to initiate T cell proliferative responses. Our studies demonstrated that all mouse strains tested gave strong proliferative responses with SRV-2 virus. In contrast, SRV-1 virus induced T cell proliferative responses only in H-2k mouse strains. This apparent major histocompatibility complex (MHC)-restriction of SRV-1 virus-induced T cell proliferation correlates with the increased pathogenicity of SRV-1 virus in rhesus monkeys. The SRV envelope peptide 233-249 which is shared by both SRV-1 and SRV-2 virus initiates strong proliferative responses in both SRV-1 and SRV-2 virus immunized mice. The SRV-2 envelope peptide 96-102 initiates significant proliferative responses in SRV-2 immunized mice, and constitutes both a T and B cell epitope. The SRV-2 envelope peptide 127-152 has a 70% homology with the C-terminal region of SRV-1 peptide 142-167. The ability of SRV-2 peptide 127-152 to initiate T cell proliferation in SRV-1 virus immunized mice and the failure of the SRV-1 peptide 142-162 to initiate proliferation suggests that the region encompassing residues 160-167 must represent a T cell epitope in mice immunized with SRV-1 virus.

Amino Acid Sequence↗
PubMedDate not supplied

SIV envelope glycoprotein epitopes recognized by antibodies from infected or vaccinated rhesus macaques.

We analyzed SIV-specific monkey sera to localize B-cell epitopes of the envelope glycoprotein of SIV (gp130), using overlapping synthetic peptides representing the entire SIV gp130 protein and sera from experimentally infected monkeys and monkeys immunized with whole, inactivated SIV. A B-cell epitope which induces neutralizing antibody production and T-cell responses was characterized as well as a new B-cell epitope and a previously described neutralizing epitopes. Vaccinated monkey sera recognize the three epitopes differentially relative to unimmunized controls, and a correlation appears to exist between degree of cross-neutralization by infected monkey sera and degree of binding to these three regions.

Amino Acid Sequence↗
PubMedDate not supplied

Type D SRV-2 virus-specific CD8+ and CD4- CD8- T cells that regulate virus-induced T cell proliferation in Celebes macaques.

These studies defined SRV-2 envelope peptides 96-102, 127-152, and 233-249 as T cell epitopes that induce significant T cell proliferation. Peripheral blood lymphocytes of Celebes macaques (Macaca nigra) exposed to SRV-2 and currently virus- antibody+, cultured with SRV-2 virus show strongly suppressed T cell responses and have two immunoregulatory T cell populations.

Animals↗