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R C Kennedy

Publications and source records attributed to R C Kennedy.

At least 73 records · Page 4Linked to original sources
PubMed1994

A bactericidal antibody to Borrelia burgdorferi is directed against a variable region of the OspB protein.

Borrelia burgdorferi, an agent of Lyme disease, is killed by some monoclonal antibodies in the absence of complement or phagocytes. In the present study, the bactericidal action of monoclonal antibodies against B. burgdorferi and B. hermsii, a cause of relapsing fever, was further characterized. H6831, an antibody recognizing the OspB proteins of some B. burgdorferi strains, and H4825, an antibody specific for one serotype of B. hermsii, were purified, and Fab fragments of the antibodies were prepared. In time-kill studies, more than 99.9% of strain B31 B. burgdorferi cells were killed after 30 min of exposure to H6831 Fab fragments. The MBC of the Fab fragments was 10 micrograms/ml. Electron microscopy revealed that the bactericidal Fab fragments produced numerous blebs and cell lysis of the borrelias for which they were specific. To identify the epitope for H6831, the OspB sequences of H6831-susceptible and -resistant strains and mutants were determined. The deduced OspB proteins of all H6831-resistant strains and mutants differed from the strain B31 OspB at residue 253. Murine antisera raised against a 21-mer synthetic peptide representing the region around residue 253 were specific for strain B31 by Western blot (immunoblot) and growth inhibition assays. Furthermore, the antipeptide serum inhibited the binding of H6831 to whole borrelias. These findings indicated that the linear component of the bactericidal antibody's epitope was located at or near residue 253.

Amino Acid Sequence↗
PubMed1994

Comparison of nonhuman primate antibodies against Haemophilus influenzae type b polysaccharide with human antibodies in oligoclonality and in vivo protective potency.

Nonhuman primates are often used as a model for studying vaccines for humans. However, it is not always clear how closely the antibody responses in these species mimic human responses. Recent studies have characterized the human antibody response to Haemophilus influenzae type b (Hib) in great detail. In this study, we have compared the antibody response to Hib of humans with those of other primates. Studies of isoelectric points and V kappa subgroup usage show that, like humans, nonhuman primates produce oligoclonal antibodies. Also, monkey antibodies to the Hib polysaccharide are as protective as human antibodies in an in vivo model of Hib infection. Thus, we conclude that nonhuman primates produce antibodies to Hib polysaccharide that are structurally and functionally similar to human antibodies and are a good model for testing human vaccines.

Animals↗
PubMed1994

Anti-idiotypes and their application under autoimmune, neoplastic, and infectious conditions.

Idiotypes and anti-idiotypes are becoming widely used in various experimental applications in multiple fields of research. Administration of anti-idiotypes has been attempted in order to manipulate immune reactions affecting autoimmune, neoplastic, and infectious processes. Immunization with anti-idiotypes and idiotypes may change the autoantibody expression in autoimmune diseases. In certain experimental models administration of anti-idiotypes and idiotypes may even propagate the induction of autoimmune-like disorders. Internal image bearing anti-idiotypes may provide an effective tool in the combat of neoplastic and infectious diseases. Such anti-idiotypes may resemble the structure of neoplastic cell antigen or mimic the composition of a contagious viral antigen. This review will deal in detail with the various aspects of idiotype and anti-idiotype immunomanipulation.

AIDS Vaccines↗
PubMed1993

Comparison of humoral immune responses and tumor immunity in mice immunized with recombinant SV40 large tumor antigen and a monoclonal anti-idiotype.

We compared the humoral immune responses induced in BALB/c mice by immunization with recombinant SV40 large tumor antigen (T-ag) with those induced by a monoclonal anti-idiotype (anti-Id), designated 58D, that is specific for SV40 T-ag-induced Id network components. We also challenged immunized mice with a lethal dose of SV40-transformed cells to assess in vivo tumor immunity. Two biweekly immunization with either SV40 T-ag or anti-Id 58D induced humoral responses that recognized both SV40 T-ag and anti-Id 58D. Four biweekly immunizations with SV40 T-ag increased the antigen-specific antibody titers and decreased the response to anti-Id 58D, while four biweekly immunizations of anti-Id 58D increased antibody titers to both itself and SV40 T-ag. Comparison of specific T-ag epitope and idiotope specificities indicated that SV40 T-ag and anti-Id 58D immunization generated responses that recognized a similar epitope on SV40 T-ag and expressed a shared idiotope recognized by anti-Id 58D. SV40 T-ag immunized mice challenged with a lethal dose of SV40-transformed cells were completely protected and no tumors were observed. This is despite the fact that little or no SV40 T-ag-specific cytotoxic T-lymphocyte activity was detectable. In contrast, only 3 of 10 mice immunized with anti-Id 58D were protected from a lethal challenge. These results indicate that, although monoclonal anti-Id immunization can induce responses that recognize similar SV40 T-ag epitopes and express shared idiotopes associated with antibodies to SV40 T-ag, the recombinant antigen itself induces superior in vivo tumor immunity.

Animals↗
PubMed1993

Comparison of the murine humoral immune response to recombinant simian virus 40 large tumor antigen: epitope specificity and idiotype expression.

Baculovirus-derived recombinant simian virus 40 (SV40) large tumor antigen (SV40 T-Ag) was used to immunize inbred strains of mice to compare the humoral immune responses. Specifically we examined the epitope specificities and idiotype (Id) expression on anti-(SV40 T-Ag) responses induced in BALB/c and C57BL/6 inbred strains of mice. The predominant SV40 T-Ag epitopes recognized by the anti-(SV40 T-Ag) responses appeared to differ between these two inbred strains, this being based on the ability of sera to inhibit the binding of several murine monoclonal antibodies specific for SV40 T-Ag. In addition, anti-(SV40 T-Ag) responses produced in C57BL/6 mice failed to express a previously described cross-reactive Id expressed in the anti-(SV40 T-Ag) response in BALB/c mice. This cross-reactive Id is detected by a mouse monoclonal anti-Id, designated 58D, which has been shown to represent a potential focal point for manipulating the humoral immune response to SV40-induced tumors in BALB/c mice. Together, these data indicate that the functional duality of the humoral immune response, as assessed by epitope recognition and Id expression, differs between these two inbred strains of mice when immunized with a recombinant SV40 T-Ag.

Animals↗
PubMed1993

Molecular characterization and structural modeling of immunoglobulin variable regions from murine monoclonal antibodies specific for hepatitis B virus surface antigen.

We have characterized structurally the V regions of a set of murine monoclonal antibodies designated A1.2, A3.1, and A2.1, which recognize a group-specific epitope associated with hepatitis B virus surface antigen (HBsAg). The selection of these antibodies for this characterization was based on data which indicated that A1.2 and A3.1 recognize an overlapping epitope, while A2.1 recognizes a different group-specific epitope, on the HBsAg molecule. In addition, a conformation-dependent cross reactive Id is expressed on both A1.2 and A3.1, but not on A2.1. We have determined the primary sequence structures of these three monoclonal antibodies to HBsAg (anti-HBs), and have aligned them to evaluate V region sequence homology and identify potential regions of structural homology which provide a basis for the HBsAg epitope recognition and the cross reactive Id. Both A1.2 and A3.1 express VH regions which are highly homologous to the VH NP gene family (V186-2), both use members of the DSP2 D region gene family and utilize the JH 2 and JH 1 J gene segments, respectively. Alternatively, A2.1 is related to the VH J558 gene family and expresses a fusion of the DFL16.1 and DQ52 D gene regions in conjunction with the MH 1 gene segment. Each of these three monoclonal anti-HBs utilize light chains from the V kappa 21 and the J kappa 4 gene families. Primary amino acid sequence data were employed to construct computer generated models of the A1.2, A3.1, and A2.1 V regions to determine potential antigen combining site structures and the basis for the expression of the cross reactive Id. These results are discussed in terms of potential interaction sites with HBsAg and V region sites involved in Id expression.

Amino Acid Sequence↗
PubMed1993

Anti-peptide reagent identifies a primary-structure-dependent, cross-reactive idiotype expressed on heavy and light chains from a murine monoclonal anti-CD4.

A synthetic peptide corresponding to the second complementarity determining region (CDR2) of the immunoglobulin (Ig) variable (V) region heavy (H) chain (CDR2VH) of anti-Leu3a, a murine monoclonal antibody specific for the human CD4 molecule, was used to elicit the production of specific rabbit anti-peptide antibodies. The rabbit anti-peptide antiserum was tested for reactivity against the immunizing peptide, anti-Leu3a, and a panel of mouse monoclonal anti-CD4. Only the immunizing peptide and anti-Leu3a were recognized by ELISA, whereas the H chains of anti-Leu3a and five other monoclonal anti-CD4 preparations were recognized by Western blot analysis. These data suggest that linear structures corresponding to the CDR2VH are not normally exposed on the surface of these monoclonal antibodies and become accessible only upon unfolding of the Ig molecule. In addition, Western blot analysis demonstrated that the anti-CDR2VH peptide antiserum was able to recognize the Ig light (L) chain of anti-Leu3a. This reactivity to both H and L chains from anti-Leu3a was ascribed to a homologous five amino acid sequence region shared by the two chains. The region of homology was associated with the third framework (FR3) of the L chain and was included as a portion of the sequence in the CDR2VH synthetic peptide. This observation was confirmed by the ability of the CDR2VH anti-peptide antiserum to bind the L chains of three mouse myeloma proteins that exhibited the five amino acid sequence region of homology within their respective FR3. Together, these data provide information on the structural basis of idiotypes shared by the H and L chains from the same antibody molecule and indicate that five amino acids might be sufficient to define a minimal continuous idiotypic determinant.

Amino Acid Sequence↗
PubMed1993

Longitudinal analysis of the humoral immune response to human immunodeficiency virus type 1 (HIV-1) gp160 epitopes in rapidly progressing and nonprogressing HIV-1-infected subjects.

Antibody response to conserved human immunodeficiency virus type 1 (HIV-1)IIIB gp160 epitopes was longitudinally examined in HIV-1-infected persons. Twelve hundred individuals were evaluated, and sequential sera from 25 rapidly progressing (RP) and 30 nonprogressing (NP) subjects collected over an average of 4 years were examined. Initial sera from the RP group contained greater reactivity to a gp120 epitope defined by peptide 503-528 than did sera from the NP group (P < .001). Reactivity declined with sequential sera for the RP group, paralleling disease progression. Conversely, antibody recognition to this site developed in 23% of the NP group with time. However, 60% of the NP group never developed a response to this epitope. This suggests sequential examination of antibody response to an epitope within the gp120 carboxyl-terminus may have prognostic significance. No association between antibodies directed against the gp160 epitopes and in vitro neutralizing activity against HIV-1IIIB was observed.

Adult↗
PubMed1993

Immunization of mice with baculovirus-derived recombinant SV40 large tumour antigen induces protective tumour immunity to a lethal challenge with SV40-transformed cells.

In this study, we examined the humoral immune responses and in vivo tumour immunity induced by baculovirus recombinant simian virus 40 (SV40) large tumour antigen (rSV40 T-ag). BALB/c mice immunized with rSV40 T-ag produced antibody responses that recognized SV40 large tumour antigen (T-ag) by ELISA. Analysis of these anti-SV40 T-ag responses indicated that the antibodies recognized epitopes associated with both the carboxy and amino terminus of SV40 T-ag. This pattern of SV40 T-ag epitope recognition was similar to that observed in anti-SV40 T-ag responses induced by inoculation with irradiated SV40-transformed cells. Mice immunized with either rSV40 T-ag or with the inactivated transformed cells were protected from a subsequent in vivo lethal tumour challenge with live SV40-transformed cells. These studies suggest that humoral immune responses induced by rSV40 T-ag are similar in epitope specificity to that induced by inactivated SV40-transformed cells. In addition, recombinant tumour-specific antigens from papovaviruses, such as SV40, can be used to induce tumour immunity which protects from a subsequent lethal tumour challenge. This study may provide insight into the use of recombinant tumour antigens as putative tumour vaccines and in the development of active immunotherapeutic strategies for treating virus-induced cancers.

Animals↗
PubMed1993

HIV-induced syncytia of a T cell line form single giant pseudopods and are motile.

The human immunodeficiency virus, HIV, induces syncytium formation in cultures of many T cell lines. These syncytia have previously been viewed as disorganized fusion products in the throes of death. Evidence is presented that in HIV1-infected SupT1 cultures, syncytia five times to over one hundred times larger than single cells organize their many nuclei into blastula-like balls, reorganize their cytoskeleton to mimic that of a single cell, and extend single, giant pseudopods in a polar fashion. Medium-sized syncytia are capable of translocation through extension of these giant pseudopods. The rate of translocation of syncytia is comparable to that of single cells. Single cell motility, syncytium motility and pseudopod extension also appear to play roles in the recruitment of cells into syncytia. Finally, condensation of F-actin at cell-syncytium and syncytium-syncytium adhesion sites suggests the involvement of the cytoskeleton in the adhesion and/or subsequent fusion event. These results suggest that the fusion events involved in HIV-induced syncytia formation involve both cell motility and reorganization of the cytoskeleton, and demonstrate that syncytia are highly organized, motile entities.

Actins↗
PubMed1993

Antibody reactivity to synthetic peptides representing the principal neutralizing determinant of HIV-1 in mouse strains following repeated immunization with recombinant gp160.

The third variable region (V3) of the HIV-1 gp120 envelope molecule appears to represent a target for naturally occurring neutralizing antibodies in HIV-1-infected individuals. In this report, we examined the extent of antibody cross-reactivity to a panel of V3-based synthetic peptides in six inbred strains of mice following repeated immunization with a baculovirus-derived recombinant gp160 (rgp160) preparation formulated with alum. The amino acid sequence of the rgp160 used in these immunizations was based upon the HIV-1 IIIB (LAI) isolate. Following five injections with rgp160, all six strains developed antibodies to the homologous IIIB-based V3 peptides, designated 304-321 and RP135. However, antibody cross-reactivity to the other nonhomologous V3 peptides was either undetectable or limited among the strains of mice examined. No in vitro neutralizing activity against HIV-1 was observed in sera from any of the six inbred strains of mice that were examined. These results suggest that repeated immunization of mouse strains with a rgp160/alum formulation leads to nonneutralizing antibodies directed against the V3 region which remain predominantly type specific.

Amino Acid Sequence↗
PubMed1992

Characteristics of murine monoclonal anti-CD4. Epitope recognition, idiotype expression, and variable region gene sequence.

We have characterized a series of mouse monoclonal anti-CD4 and describe both their CD4 epitope recognition and Id expression. We also determined the V region gene sequences of these antibodies in an attempt to correlate epitope recognition and Id expression with V region sequence. All of these preparations recognize epitopes that cluster around the HIV gp120 binding site on the human CD4 molecule. However, we observed differences in epitope recognition among the anti-CD4 preparations, based on either competitive inhibition assays or functional assays, such as syncytium inhibition. Analysis of Id specificities using a polyclonal anti-Id generated against anti-Leu 3a indicated that five of the seven monoclonal anti-CD4 expressed a shared Id. Based on V region gene sequences, the V region kappa-chain (V[kappa]) from each of the seven antibodies was encoded by the V[kappa]21 gene family and expressed the J[kappa]4 gene segment. Those preparations that expressed the shared Id with anti-Leu 3a have virtually identical V[kappa] sequences, with a high degree of homology in the CDR. The VH region gene sequences of six of the seven antibodies also shared overall homology and appeared to be encoded by the J558 VH gene family. The seventh anti-CD4 VH region is encoded for by the VHGAM gene family. The majority of these antibodies used JH3 gene segment, although the JH2 and JH4 gene segments were also represented. In addition, several of these antibodies share a common sequence organization within their V-D-J joining regions that appears to involve N and P sequences to generate unique D segments. Together, these data suggest that differences in epitope recognition among the monoclonal anti-CD4 may reflect sequence variability primarily within the CDR3 region of both V[kappa] and VH. The basis for the detection of a shared Id most likely reflects the high degree of homology within the V[kappa] region sequences. In addition, these data, which are based on a limited analysis, suggest the possible restricted use of V region germ-line gene families in the secondary antibody response of BALB/c mice to specific epitopes on the human CD4 molecule.

Amino Acid Sequence↗
PubMed1992

Fine specificity of the humoral immune response to HIV-1 GP160 in HIV-1 infected individuals from Tanzania.

A total of 160 sera from HIV-1 infected individuals from Tanzania were examined for their fine specificity characteristics relative to 9 synthetic peptides that define HIV-1 gp160 epitopes. Immunorecessive and immunodominant epitopes were identified in both gp120 and gp41 based on serologic reactivity of these HIV-1 infected sera. A significant difference in fine specificity among HIV-1 infected individuals from Tanzania and the United States was observed for an immunodominant gp41 epitope. No significant differences in reactivity among asymptomatic vs. symptomatic HIV-1 infected individuals were detected for the selected HIV-1 gp160 epitopes defined by these peptides. The majority of sera from HIV-1 infected Tanzanians contained antibodies that recognized a peptide corresponding to the V3 region of gp120 from the HIV-1 MN isolate. These data suggest that regional isolates of HIV-1 may exist in Tanzania that differ from HIV-1 isolated in the United States. However, based on serology, HIV-1 isolates exhibiting sequences with HIV-1 MN V3 similarity may also be prevalent in Tanzania. The results of this study may be useful for the design of more effective AIDS diagnostic and therapeutic products for use worldwide.

Amino Acid Sequence↗
PubMed1992

Idiotype network components are involved in the murine immune response to simian virus 40 large tumor antigen.

Baculovirus-derived recombinant simian virus 40 (SV40) large tumor antigen (SV40 T-Ag), a monoclonal antibody specific for SV40 T-Ag (Ab-1 preparation), and a monoclonal anti-idiotypic antibody (anti-Id), designated 58D, were used to analyze the humoral immune response of Balb/c mice either immunized with recombinant SV40 T-Ag or challenged with SV40-transformed cells. Inhibition assays indicated that antibodies from mice immunized with SV40 T-Ag and from those bearing SV40 tumor inhibited the SV40 T-Ag/Ab-1 reaction. These data suggested that the antibody response in immunized or tumor-challenged mice recognized similar epitope(s) on SV40 T-Ag to that detected by the monoclonal Ab-1. These anti-(SV40 T-Ag) response antibodies also inhibited the Ab-1/anti-Id reaction and recognized the anti-Id in direct binding assays. Together, these data indicate that murine anti-(SV40 T-Ag) responses shared an idiotope with a monoclonal anti-(SV40 T-Ag) Ab-1 preparation. This idiotope, which is recognized by the monoclonal anti-Id preparation, 58D, appears to be involved in the humoral immune response to SV40 T-Ag in both SV40-T-Ag-immunized and tumor-bearing mice. The monoclonal anti-Id preparation may represent a focal point for manipulating the humoral immune response to tumors induced by SV40-transformed cells.

Animals↗
PubMed1992

Anti-idiotype vaccines in toxicology.

The majority of naturally occurring biological and chemical toxins are highly lethal, nonproteinaceous, low molecular weight substances which exert their toxicity through a variety of mechanisms. Their relative small size and extreme in vivo toxicity have hampered the development of protective vaccines. We have investigated the feasibility of anti-idiotype-based vaccines which utilize antibodies for inducing a systemic and protective immunity against the in vivo toxicity of some of these toxic substances. A murine IgG1 monoclonal anti-T-2 mycotoxin antibody protective against mycotoxin toxicity was generated. This antibody was used to produce a second generation monoclonal anti-idiotype antibody which was capable of serologically mimicking the tertiary conformation of the nominal antigen, i.e., T-2 mycotoxin. Administration of the monoclonal anti-idiotype antibody to mice induced a circulating and protective antibody response against the in vitro and in vivo toxicity of T-2 mycotoxin. Antibody-based vaccines may represent the only safe and effective strategy for the design of protective vaccines against small nonproteinaceous toxic compounds whose extreme toxicity prevents their use as safe immunogens. The potential of antibody-based vaccines for producing protective immunity against low molecular weight chemical and biological toxins is discussed.

Animals↗