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At least 127 records · Page 7Linked to original sources
PubMed1994

DNA inoculation induces protective in vivo immune responses against cellular challenge with HIV-1 antigen-expressing cells.

Direct DNA inoculation induces immune responses through the delivery of nonreplicating transcription units that drive the synthesis of specific foreign proteins within the inoculated host. These proteins are processed within host cells and through association with relevant MHC antigens that can become the subject of immune surveillance and elicit immune responses against pathogens. Direct introduction of DNA into mice has been reported to be antigenic as demonstrated by the use of this technique to develop immune responses against human growth hormone, influenza proteins, as well as HIV-1 proteins. Most recently the demonstration of the use of this technology to produce anti-HIV-1 immune responses has been reported in nonhuman primates. Accordingly a more detailed analysis of this technology could generate important insight into the generality of this approach for immune therapy or vaccine design. In this article we further our investigation of direct DNA inoculation as a tool for induction of relevant immune responses against HIV-1 in vivo. We demonstrate expression of HIV-1 antigens in the inoculated muscle of animals. Inoculated animals demonstrate significant cytotoxic T cell responses against HIV-1 antigen-expressing targets. Furthermore, using a novel challenge system, we demonstrate that the majority of immunized animals can reject lethal, HIV-1 antigen-expressing cell challenge in an antigen-specific manner. This technology has relevance for the development of immunization strategies against HIV as it provides for specific antigen production in vivo without the use of infectious agents.

AIDS Vaccines↗
PubMed1984

A cytolytic human T lymphocyte clone differentially recognizing HLA-B27 subtypes.

A cytolytic human T cell (CTL) clone, designated F/M-F159, has been produced, the lytic specificity of which distinguishes subtypes of HLA-B27. This was demonstrated in cell-mediated lympholysis (CML) assays of: 1) a panel of target cells from unrelated donors, 75 B27 + and 36 B27-; 2) six families, including 20 B27 + and 14 B27- individuals; and 3) B27 + and B27- variants of a B27+ lymphoblastoid cell line (LCL). Specificity of F/M-F159 for HLA-B27 was confirmed by blocking studies with monoclonal antibodies. Lysis of B27 + targets reactive with the anti-B27 monoclonal antibody B27M2 was 30-104%, while lysis of B27 +, B27M2- targets was 4-22%. Lysis of B27- targets expressing HLA-Bw47, known to be cross-reactive with the B27M2 antibody, was 10 to 19%, while lysis of all other B27- targets was less than or equal to 10%. Clone F/M-F159 lysed B27 + targets, and failed to lyse B27- targets, irrespective of the clinical status of the cell donors. It is concluded that F/M-F159 recognizes an epitope present on the majority of serologically identified HLA-B27 molecules and that this epitope is closely related to, but not identical with, the epitope recognized by the antibody B27M2. These findings are interpreted as supporting a direct role for HLA-B27 in disease pathogenesis.

Antibodies, Monoclonal↗
PubMed1993

An endogenously synthesized decamer peptide efficiently primes cytotoxic T cells specific for the HIV-1 envelope glycoprotein.

The immunodominant H-2Dd-restricted cytotoxic T lymphocyte (CTL) response to the HIV-1 gp160 envelope glycoprotein maps to a single determinant in the V3 loop, designated p18. Using a series of peptides synthesized on pins we have determined that the minimal core sequence of this determinant required for CTL recognition comprises 8 amino acids (residues 320-327). However, 9mer and 10mer peptides containing this core sequence were more effective than the 8mer peptide at sensitizing Dd-expressing target cells. To analyze the antigenicity of endogenously synthesized p18, minigenes encoding a 10-amino acid determinant (residues 318-327) and a 67-amino acid peptide (residues 281-348; containing the V3 loop) were expressed using vaccinia virus (Vac) recombinants. Both peptides were as effective as wild-type gp160 in their ability to sensitize target cells for lysis by gp160-specific CTL. Immunization of BALB/c mice with Vac recombinants encoding both gp160 peptides elicited gp160-specific CTL. These data demonstrate that both the V3 loop itself and a 10-residue epitope are sufficient to prime CTL in vivo and strongly support the potential use of minigene-encoded CTL epitopes for recombinant vaccines designed to induce protective T cell-mediated immunity against HIV-1.

AIDS Vaccines↗
PubMed1995

Identification of a spatially specific enhancer element in the chicken Msx-2 gene that regulates its expression in the apical ectodermal ridge of the developing limb buds of transgenic mice.

Msx-2 is a member of the Msx family of homeobox-containing genes expressed in a variety of embryonic tissues involved in epithelial-mesenchymal interactions and pattern formation. In the developing chick limb bud, Msx-2 is expressed in the apical ectodermal ridge, which plays a crucial role in directing the growth and patterning of limb mesoderm. In addition, Msx-2 is expressed in the anterior nonskeletal-forming mesoderm of the limb bud, in the posterior necrotic zone, and in the interdigital mesenchyme. Studies of the altered expression patterns of Msx-2 in amelic and polydactylous mutant chick limbs have suggested that the apical ectodermal ridge and mesodermal domains of Msx-2 expression are independently regulated and that there might be separate cis-regulatory elements in the Msx-2 gene controlling its spatially distinct domains of expression. To test this hypothesis, we have isolated the chicken Msx-2 gene and have tested the ability of various regions of the gene to target expression of LacZ reporter gene to specific regions of the limbs of transgenic mice. A variety of these constructs are consistently expressed only in the apical ectodermal ridge and the ectoderm of the genital tubercle and are not expressed in the mesoderm of the limb bud or in other regions of the embryo where the endogenous Msx-2 gene is expressed. These results suggest the presence of spatially specific cis-regulatory elements in the Msx-2 gene. We identified a 348-bp region in the 5' flanking region of the Msx-2 gene which can act as an apical ectodermal ridge enhancer element when placed in reverse orientation in front of the reporter gene with transcription initiation directed by the minimal hsp68 promoter.

Animals↗
PubMed2025

Identification of a robust promoter in mouse and human hepatocytes by in vivo biopanning of a barcoded AAV library.

Recombinant adeno-associated viruses (AAVs) are leading vectors for in vivo human gene therapy. An integral vector element is promoters, which control transgene expression in either a ubiquitous or cell-type-selective manner. Identifying optimal capsid-promoter combinations is challenging, especially when considering on- versus off-target expression. Here, we report a pipeline for in vivo promoter biopanning in AAV building on our AAV capsid barcoding technology and illustrate its potential by screening 53 promoters in 16 murine tissues using an AAV9 vector. Surprisingly, the 2.2-kb human glial fibrillary acidic protein (GFAP) promoter was the top hit in the liver, where it outperformed robust benchmarks such as the human α-1-antitrypsin promoter or the clinically used liver-specific promoter 1 (LP1). Analysis of hepatic cell populations revealed preferred GFAP promoter activity in hepatocytes. Notably, the GFAP promoter also surpassed the LP1 and cytomegalovirus promoters in human hepatocytes engrafted in an immune-deficient mouse. These findings establish the GFAP promoter as an exciting alternative for research and clinical applications requiring efficient and specific transgene expression in hepatocytes. Our pipeline expands the arsenal of technologies for high-throughput in vivo screening of viral vector components and is compatible with capsid barcoding, facilitating the combinatorial interrogation of complex AAV libraries.

Dependovirus↗
PubMed1989

GP120 specific cellular cytotoxicity in HIV-1 seropositive individuals. Evidence for circulating CD16+ effector cells armed in vivo with cytophilic antibody.

Fresh circulating PBMC from HIV-1 seropositive individuals have been found to mediate specific, non-MHC restricted lysis of targets expressing the major envelope glycoprotein of HIV-1, gp120, in 6-h 51Cr release assays. This gp120 specific cell-mediated cytotoxicity (CMC) is broadly reactive against target cells infected with a wide range of viral isolates, is IL-2 augmentable, and is mediated by a CD16+, Leu-7+, CD15-, CD3- population of NK/K cells. The presence of FcR (CD16) on these cells suggested that the lytic specificity for gp120 might be directed by cytophilic antibody bound to the cell surface. Affinity purified F(ab')2 antibody fragments specific for the Fc and F(ab')2 portions of human IgG were used in attempts to block gp120 specific lysis. A 1/50 dilution of these antibodies inhibited gp120 specific cytolytic activity by more than 90% while exhibiting a minimal effect on NK/K cell lysis of K562 targets. The blocking activity of these fragments demonstrates the direct involvement of cytophilic antibody in CMC. In attempts to isolate this cytophilic anti-HIV-1 antibody, short 56 degrees C incubations were used to dissociate antibodies from the surface of PBMC of seropositive individuals. The supernatants generated in this manner exhibited specific gp120 activity in antibody-dependent cellular cytotoxicity assays. The ability of Staphylococcal protein A to remove this activity confirms the presence of cytophilic antibody on freshly isolated PBMC. Selective enrichment of specific cell subpopulations revealed the origin of the cytophilic antibody to be CD16+ NK/K cells and not B cells, T cells, or monocytes/macrophages. These studies show that the gp120-specific CMC seen in HIV-1 seropositive individuals is directed by cytophilic antibody bound to circulating CD16+ NK/K cells and represents a form of direct antibody-dependent cellular cytotoxicity which may provide a primary cytotoxic host defense.

Antibody Specificity↗
PubMedDate not supplied

Functional interaction between human T-cell protein CD4 and the major histocompatibility complex HLA-DR antigen.

Mature T cells segregate phenotypically into one of two classes: those that express the surface glycoprotein CD4, and those that express the glycoprotein CD8. The CD4 molecule is expressed primarily on helper T cells whereas CD8 is found on cytotoxic and suppressor cells. A more stringent association exists, however, between these T-cell subsets and the major histocompatibility complex (MHC) gene products recognized by their T-cell receptors (TCRs). CD8+ lymphocytes interact with targets expressing class I MHC gene products, whereas CD4+ cells interact with class II MHC-bearing targets. To explain this association, it has been proposed that these 'accessory' molecules bind to monomorphic regions of the MHC proteins on the target cell, CD4 to class II and CD8 to class I products. This binding could hold the T cell and its target together, thus improving the probability of the formation of the trimolecular antigen: MHC: TCR complex. Because the TCR on CD4+ cells binds antigen in association with class II MHC, it has been difficult to design experiments to detect the association of CD4 with a class II molecule. To address this issue, we devised a xenogeneic system in which human CD4 complementary DNA was transfected into the murine CD4-, CD8- T-cell hybridoma 3DT-52.5.8, the TCR of which recognizes the murine class I molecule H-2Dd. The murine H-2Dd-bearing target cell line, P815, was cotransfected with human class II HLA-DR alpha, beta and invariant chain cDNAs. Co-culture of the parental T-cell and P815 lines, or of one parental and one transfected line resulted in a low baseline response. In contrast, a substantial increase in response was observed when CD4+ 3DT-52.5.8 cells were co-cultured with HLA-DR+ P815 cells. This result strongly indicates that CD4:HLA-DR binding occurs in this system and that this interaction augments T-cell activation.

Animals↗
PubMed1995

Oligoclonal CD8 lymphocytes from persons with asymptomatic human immunodeficiency virus (HIV) type 1 infection inhibit HIV-1 replication.

CD8 lymphocytes from asymptomatic human immunodeficiency virus (HIV) type 1-infected patients can suppress virus production from infected CD4 cells. Suppressive activity is separate and distinct from cytotoxic T lymphocyte (CTL) reactivities and is likely mediated by a soluble factor(s). The majority of HIV-1 suppression studies have been done in the context of bulk CD8 cell cultures. In this study, viral suppression was characterized by clonal populations of CD8 cells derived from HIV-1-infected patients. Most of the suppressive clones were devoid of detectable CTL reactivity against env-, gag-, pol-, and nef-expressing targets. Among the suppressive clones derived from an individual patient, a marked heterogeneity was evident with respect to phenotypic markers, cytokine production, and T cell receptor V beta expression. These results suggest that noncytolytic virus suppression is oligoclonal in nature. Clones provide tools for future studies aimed at understanding the mechanism of suppression and identifying the suppressive factor.

CD8-Positive T-Lymphocytes↗
PubMed2026

Genome-Wide Characterization of β-Glucosidase (TaBGLU) Genes in Bread Wheat and Their Expression Under Drought, Cold, and Combined Stress.

Glycoside hydrolase 1 (GH1) β-glucosidases were known to activate hormone conjugates and defense metabolites, yet their genomic organization and stress-response dynamics in wheat remained incompletely defined. We therefore performed an integrated characterization of TaBGLUs spanning phylogeny, gene structure and conserved motifs, subcellular localization, promoter cis-elements, Gene Ontology enrichment, protein-protein interaction networks, and targeted expression profiling. Wheat TaBGLUs partitioned into well-supported clades that shared canonical GH1 catalytic residues and a largely conserved motif scaffold. Subcellular localization predictions indicated predominant nuclear and chloroplast targeting, with a smaller cohort directed to secretory or endomembrane compartments. Promoters were enriched for light-responsive, hormone-related (ABA, JA/SA, auxin, GA) and stress-associated (MYB/WRKY, heat, low temperature) cis-elements, and functional annotations were consistent with roles in carbohydrate and cell-wall metabolism, hormone homeostasis, and defense. Network analysis revealed a densely connected TaBGLU submodule embedded within broader carbohydrate and defense interaction networks, suggesting coordinated or cooperative functions. Expression profiling under cold, drought, and combined drought and cold demonstrated broad stress inducibility, with early activation detected by 6 h, cold-responsive maxima typically at 12 h, drought-responsive peaks predominating at 24 h, and combined stress eliciting both earlier and more sustained expression maxima between 12-24 h. Representative strongly responsive genes included TaBGLU20, TaBGLU44, TaBGLU6, and TaBGLU23, which showed pronounced late induction under combined stress, TaBGLU30, which exhibited an earlier combined-stress peak, and TaBGLU12, which displayed a marked late drought-specific response. Taken together, this integrated genomic, regulatory, and expression atlas refined the wheat BGLU repertoire relative to previous gene model inventories, highlighted candidate TaBGLUs with central network positions and strong stress inducibility, and provided concrete entry points for functional validation and breeding for improved stress resilience.

Triticum↗
PubMed1995

Human COL2A1-directed SV40 T antigen expression in transgenic and chimeric mice results in abnormal skeletal development.

The ability of SV40 T antigen to cause abnormalities in cartilage development in transgenic mice and chimeras has been tested. The cis-regulatory elements of the COL2A1 gene were used to target expression of SV40 T antigen to differentiating chondrocytes in transgenic mice and chimeras derived from embryonal stem (ES) cells bearing the same transgene. The major phenotypic consequences of transgenic (pAL21) expression are malformed skeleton, disproportionate dwarfism, and perinatal/neonatal death. Expression of T antigen was tissue specific and in the main characteristic of the mouse alpha 1(II) collagen gene. Chondrocyte densities and levels of alpha 1(II) collagen mRNAs were reduced in the transgenic mice. Islands of cells which express cartilage characteristic genes such as type IIB procollagen, long form alpha 1(IX) collagen, alpha 2(XI) collagen, and aggrecan were found in the articular and growth cartilages of pAL21 chimeric fetuses and neonates. But these cells, which were expressing T antigen, were not properly organized into columns of proliferating chondrocytes. Levels of alpha 1(II) collagen mRNA were reduced in these chondrocytes. In addition, these cells did not express type X collagen, a marker for hypertrophic chondrocytes. The skeletal abnormality in pAL21 mice may therefore be due to a retardation of chondrocyte maturation or an impaired ability of chondrocytes to complete terminal differentiation and an associated paucity of some cartilage matrix components.

Animals↗
PubMed1995

A truncated herpes simplex virus thymidine kinase phosphorylates thymidine and nucleoside analogs and does not cause sterility in transgenic mice.

Dividing eukaryotic cells expressing the herpes simplex virus type 1 thymidine kinase (TK) gene are sensitive to the cytotoxic effect of nucleoside analogs such as acyclovir or ganciclovir (GCV). Transgenic mice with cell-targeted expression of this conditional toxin have been used to create animals with temporally controlled cell-specific ablation. In these animal models, which allow the study of the physiological importance of a cell type, males are sterile. In this study, we showed that this phenomenon is due to testis-specific high-level expression of short TK transcripts initiated mainly upstream of the second internal ATG of the TK gene. This expression is DNA methylation independent. To obtain a suicide gene that does not cause male infertility, we generated and analyzed the properties of a truncated TK (delta TK) lacking the sequences upstream of the second ATG. We showed that when expressed at sufficient levels, the functional properties of delta TK are similar to those of TK in terms of thymidine or GCV phosphorylation. This translated into a similar GCV-dependent toxicity for delta TK- or TK-expressing cells, both in vitro and in transgenic mice. However, delta TK behaved differently from TK in two ways. First, it did not cause sterility in delta TK transgenic males. Second, low-level delta TK RNA expression did not confer sensitivity to GCV. The uses of delta TK in cell-specific ablation in transgenic mice and in gene therapy are discussed.

Animals↗
PubMed1983

Cross-reactivity patterns of influenza-specific cytotoxic T lymphocytes from H-2Kb mutant mice.

Limit dilution cultures were used to test for influenza immune T cell populations from bm1 and bm3 mutant mice that were not lytic for virus-infected targets expressing the Kb and Db major histocompatibility complex glycoproteins. Both Kbm3- and Kbm1-restricted cytotoxic T cells were detected. Such effectors showed minimal cross-recognition of influenza on other mutant targets, except for the case of bm1 and bm10 targets. This is dissimilar to previous findings concerning vaccinia presentation in which bm3+bm11, bm1+bm9, and bm3+bm9 pairs each showed high cross-reactivity. These differences illustrate the role of the H-2K glycoprotein in immune responsiveness. Not only are multiple determinants on each H-2K glycoprotein involved in antigen presentation, they appear to play differential roles in the presentation of different viral antigens.

Animals↗
PubMed2026

AGRN activates GPX4 via the Wnt/beta-catenin signaling pathway to suppress ferroptosis in cervical cancer cells.

Cervical cancer remains a leading cause of cancer-related deaths among women worldwide. Targeting ferroptosis, a regulated form of cell death driven by lipid peroxidation, has emerged as a promising therapeutic strategy. This study aimed to elucidate the mechanisms by which cervical cancer cells acquire resistance to ferroptosis. AGRN expression and its prognostic significance were analyzed in cervical cancer using TCGA and GTEx data. In vitro, AGRN levels were measured in HeLa, CaSki, and Ect1/E6E7 cells via qRT-PCR. mRNA and protein expression levels of AGRN, beta-catenin, and ferroptosis-related markers were evaluated by qRT-PCR and western blot (WB). Cell viability, RSL3 sensitivity (IC50), and lipid ROS were assessed via CCK-8 assay and flow cytometry. In a xenograft model, RSL3's effect on tumor growth was examined. Immunohistochemistry (IHC) and molecular analyses (qRT-PCR, WB, and flow cytometry) were performed on tumor tissues to evaluate AGRN, beta-catenin, Ki-67, ferroptosis-related genes, and lipid ROS. It is found through research that, AGRN was significantly upregulated in cervical cancer tissues and cell lines. Its overexpression activated Wnt/beta-catenin signaling, resulting in elevated GPX4 and SLC7A11 levels and reduced CHAC1 and PTGS2 expression levels. These alterations decreased lipid ROS accumulation and enhanced resistance to RSL3-induced ferroptosis, an effect further confirmed in xenograft models. In short, In short, AGRN promotes ferroptosis resistance in cervical cancer by activating the Wnt/beta-catenin signaling pathway and upregulating GPX4 expression. Targeting the AGRN-Wnt/beta-catenin-GPX4 axis may represent a novel therapeutic approach for cervical cancer.

Humans↗
PubMed1995

Multiple CTL specificities against autologous HIV-1-infected BLCLs.

The cellular immune response to HIV-1 has been well studied but, in many respects, remains incompletely defined. Although CTL specificities against highly conserved HIV-1 determinants as dictated by vaccinia/HIV-1 vector constructs have been described, much less is known regarding patient cellular reactivities against autologous cells infected with HIV-1. One of the main obstacles in characterizing this cellular reactivity has been the absence of a targeting system which accurately represents the HIV infected cell in vivo and is, at the same time, adaptable for in vitro assays. Through the use of two separate strategies aimed at increasing cellular CD4 expression, we were able to infect B-lymphocyte cell lines (BLCLs) with multiple strains of HIV-1. HIV-1-infected BLCLs were recognized by autologous effector cells with cytolytic specificities against env, gag, or pol determinants. In addition, HIV-1-infected BLCLs were capable of eliciting in vitro CTL reactivities directed against env-, gag-, and pol-expressing targets. This cellular reactivity was mediated by CD8+ cells and was MHC Class I restricted, suggesting a classical CTL response. Since multiple antigens are recognized, an HIV-1-infected BLCL is a more natural representation of an in vivo cellular target than other available testing systems and should permit a more representative analysis of CTL responses during infection or following vaccination.

B-Lymphocytes↗
PubMed1995

Expression of an epidermal keratin protein in liver of transgenic mice causes structural and functional abnormalities.

To examine the role of keratin intermediate filament proteins in cell structure and function, transgenic mice were isolated that express a modified form of the human K14 keratin protein in liver hepatocytes. A modified K14 cDNA (K14.P) sequence was linked downstream of the mouse transthyretin (TTR) gene promoter and enhancer elements to achieve targeted expression in hepatocytes. Hepatocytes expressing high levels of the transgene were found to have abnormal keratin filament networks as detected by indirect immunofluorescence using an antibody specific for the transgene product. Light and electron microscopic level histological analysis of isolated liver tissue showed in many cases degenerative changes that included inflammatory infiltration, ballooning degeneration, an increase in fat containing vacuoles, and glycogen accumulation. These changes were most evident in older mice over four months of age. No indication of typical Mallory body structures were identified at either the light or electron microscopic level. To evaluate secretory function in transgenic livers, bile acid secretion rates were measured in isolated perfused liver and found to be approximately twofold lower than aged-matched controls. These findings indicate that expression of an abnormal keratin in liver epithelial cells in the in vivo setting can alter the structure and function of a tissue and suggest a role of the keratin network in cellular secretion.

Animals↗
PubMed1988

Analysis of the L1 gene product of human papillomavirus type 16 by expression in a vaccinia virus recombinant.

The L1 open reading frame of human papillomavirus type 16 (HPV16) has been expressed in vaccinia virus under the control of both the 7.5K early and late promoter, and the 4b major late promoter. Antibodies to a beta-galactosidase fusion protein containing a C-terminal portion of the HPV16 L1 gene product were used to compare the levels of L1 expression in the two recombinants, and showed that greater levels of expression were obtained when the gene was placed under the control of the 4b late promoter. Immunofluorescence studies revealed a nuclear location of the L1 gene product when expressed in vaccinia virus. Antibodies to the beta-galactosidase fusion protein detected a major polypeptide species of 57K and a minor species of 64K in Western blots of recombinant-infected cell lysates. The 64K species was not detected when cells were infected in the presence of tunicamycin, indicating that the primary translation product of the HPV16 L1 open reading frame is modified by N-linked glycosylation when expressed in vaccinia virus. Whereas antibodies to HPV16 L1 fusion proteins and to a peptide containing amino acids from the C terminus of HPV16 L1 reacted well in Western blots with the HPV16 L1 target expressed in vaccinia virus, no reactivity was observed with antibodies to bovine papillomavirus type 1 particles or to a HPV6b fusion protein.

Animals↗
PubMed1995

Polymorphism within the herpes simplex virus (HSV) ribonucleotide reductase large subunit (ICP6) confers type specificity for recognition by HSV type 1-specific cytotoxic T lymphocytes.

A panel of herpes simplex virus type 1 (HSV-1)-specific, CD8+, major histocompatibility complex class I (H-2Kb)-restricted cytotoxic T-lymphocyte (CTL) clones was derived from HSV-1-immunized C57BL/6 (H-2b) mice in order to identify the HSV-1 CTL recognition epitope(s) which confers type specificity. HSV-1 x HSV-2 intertypic recombinants were used to narrow the region encoding potential CTL recognition epitopes to within 0.51 to 0.58 map units of the HSV-1 genome. Using an inhibitor of viral DNA synthesis and an ICP6 deletion mutant, the large subunit of ribonucleotide reductase (ICP6, RR1) was identified as a target protein for these type-specific CTL. Potential CTL recognition epitopes within RR1 were located on the basis of the peptide motif predicted to bind to the MHC class I H-2Kb molecule. A peptide corresponding to residues 822 to 829 of RR1 was shown to confer susceptibility on H-2Kb-expressing target cells to lysis by the type 1-specific CTL. On the basis of a comparison of the HSV-1 RR1 epitope (residues 822 to 829) with the homologous sequence of HSV-2 RR1 (residues 828 to 836) and by the use of amino acid substitutions within synthetic peptides, we identified HSV-1 residue 828 as being largely responsible for the type specificity exhibited by HSV-1-specific CTL. This HSV-1 RR1 epitope, when expressed in recombinant simian virus 40 large T antigen in primary C57BL/6 cells, was recognized by the HSV-1 RR1-specific CTL clones. These results indicate that an early HSV protein with enzymatic activity provides a target for HSV-specific CTL and that type specificity is dictated largely by a single amino acid.

Amino Acid Sequence↗
PubMed1992

Discrepancy between in vitro measurable and in vivo virus neutralizing cytotoxic T cell reactivities. Low T cell receptor specificity and avidity sufficient for in vitro proliferation or cytotoxicity to peptide-coated target cells but not for in vivo protection.

The TCR-alpha beta of CTL recognize peptide Ag in association with MHC class I molecules. TCR binding should be highly specific to guarantee pathogen specificity and to avoid self-reactivity. Therefore, the in vivo relevance of T cells exhibiting cross-reactivities in vitro and the respective role of the TCR affinities involved are not clear. To analyze high and low avidity T cell activities both in vitro and in vivo, we investigated primary and clonal CTL responses specific for the lymphocytic choriomeningitis virus nucleoprotein 118-126 epitope in association with the two closely related H-2Ld or H-2Lq molecules. As expected, we found highly specific class I-allele-restricted CTL responses when antiviral protection or immunopathology in vivo and lysis of virus infected target cells in vitro were analyzed. In contrast, the CTL were MHC crossreactive and thus considerably less discriminatory against targets expressing high MHC-peptide densities and in proliferation assays. The data show that relatively high TCR avidities are required for virus neutralization in vivo, in contrast to in vitro analyses of peptide-coated target cells or proliferative T cell responses that may engage TCR of low avidity and broad specificity and therefore may not reflect biologically relevant TCR avidities.

Animals↗