Type IVb Hypersensitivity Reaction in the Novel Murine Model of Palladium-Induced Intraoral Allergic Contact Mucositis.

Palladium (Pd) is a component of several alloy types that are widely used in our environment, including several dental alloy types that cause adverse reactions such as hypersensitivity in the oral mucosa. However, the pathological mechanism of intraoral Pd allergies remains unclear because its animal model in the oral mucosa has not been established. In this study, we established a novel murine model of Pd-induced allergies in the oral mucosa, and explored the immune response of cytokine profiles and T cell diversity in terms of the T cell receptor. The Pd-induced allergy mouse was generated by two sensitizations with PdCl2, plus a lipopolysaccharide solution into the postauricular skin followed by a single Pd challenge of the buccal mucosa. Significant swelling and pathological features were histologically evident at five days after the challenge, and CD4-positive T cells producing high levels of T helper 2 type cytokines had accumulated in the allergic oral mucosa. Characterization of the T cell receptor repertoire in Palladium allergic mice indicated that Pd-specific T cell populations were limited in V and J genes but were diverse at the clonal level. Our model demonstrated that a Pd-specific T cell population with Th2 type response tendencies may be involved in the Pd-induced intraoral metal contact allergy.

Cross-Reactivity of Intraoral Allergic Contact Mucositis in the Nickel-Sensitized Ear Model of Metal Allergy.

Cross-reactivity of metal allergies can make metal allergy treatment complicated because the background of immune response in cross-reactions remains unknown. In clinical settings, cross-reactivity among several metals has been suspected. However, the precise mechanism of immune response in cross-reactivity is unclear. Two sensitizations with nickel, palladium, and chromium plus lipopolysaccharide solution into the postauricular skin were followed by a single nickel, palladium, and chromium challenge of the oral mucosa to generate the intraoral metal contact allergy mouse model. Results showed that the infiltrating T cells in nickel-sensitized, palladium- or chromium-challenged mice expressed CD8+ cells, cytotoxic granules, and inflammation-related cytokines. Thus, nickel ear sensitization can cause cross-reactive intraoral metal allergy.

Characterization of Metal-Specific T-Cells in Inflamed Oral Mucosa in a Novel Murine Model of Chromium-Induced Allergic Contact Dermatitis.

The element chromium (Cr) is a component of several types of alloys found in the environment, or utilized in dentistry, that may cause intraoral metal contact allergy. However, the pathological mechanism of intraoral Cr allergy remains unclear because there is no established animal model of Cr allergy in the oral mucosa. In this study, we established a novel murine model of Cr-induced intraoral metal contact allergy and elucidated the immune response in terms of cytokine profiles and T-cell receptor repertoire. Two sensitizations with Cr plus lipopolysaccharide solution into the postauricular skin were followed by a single Cr challenge of the oral mucosa to generate the intraoral metal contact allergy model. Histological examination revealed that CD3+ T-cells had infiltrated the allergic oral mucosa one day after exposure to the allergen. The increase in T-cell markers and cytokines in allergic oral mucosa was also confirmed via quantitative PCR analysis. We detected Cr-specific T-cells bearing TRAV12D-1-TRAJ22 and natural killer (NK) T-cells in the oral mucosa and lymph nodes. Our model demonstrated that Cr-specific T-cells and potent NKT-cell activation may be involved in the immune responses of Cr-induced intraoral metal contact allergy.

Pharmacological MEK inhibition promotes polyclonal T-cell reconstitution and suppresses xenogeneic GVHD.

Rapid immune reconstitution without developing graft-versus-host disease (GVHD) is required for the success of allogeneic hematopoietic stem cell transplantation. Here, we analyzed the effects of pharmacological MEK inhibition on human polyclonal T-cell reconstitution in a humanized mouse GVHD model utilizing deep sequencing-based T-cell receptor (TCR) repertoire analysis. GVHD mice exhibited a skewed TCR repertoire with a common clone within target organs. The MEK inhibitor trametinib ameliorated GVHD and enabled engraftment of diverse T-cell clones. Furthermore, trametinib also ameliorated GVHD sparing diverse T cell repertoire, even when it was given from day 15 through 28. Although tacrolimus also reduced development of GVHD, it disturbed diverse T cell reconstitution and resulted in skewed TCR repertoire. Thus, trametinib not only suppresses GVHD-inducing T cells but also promotes human T cell reconstitution in vivo, providing a novel rationale for translational studies targeting human GVHD.

Induction of oligoclonal CD8 T cell responses against pulmonary metastatic cancer by a phospholipid-conjugated TLR7 agonist.

Recent advances in cancer immunotherapy have improved patient survival. However, only a minority of patients with pulmonary metastatic disease respond to treatment with checkpoint inhibitors. As an alternate approach, we have tested the ability of systemically administered 1V270, a toll-like receptor 7 (TLR7) agonist conjugated to a phospholipid, to inhibit lung metastases in two variant murine 4T1 breast cancer models, as well as in B16 melanoma, and Lewis lung carcinoma models. In the 4T1 breast cancer models, 1V270 therapy inhibited lung metastases if given up to a week after primary tumor initiation. The treatment protocol was facilitated by the minimal toxic effects exerted by the phospholipid TLR7 agonist compared with the unconjugated agonist. 1V270 exhibited a wide therapeutic window and minimal off-target receptor binding. The 1V270 therapy inhibited colonization by tumor cells in the lungs in an NK cell dependent manner. Additional experiments revealed that single administration of 1V270 led to tumor-specific CD8+ cell-dependent adaptive immune responses that suppressed late-stage metastatic tumor growth in the lungs. T cell receptor (TCR) repertoire analyses showed that 1V270 therapy induced oligoclonal T cells in the lungs and mediastinal lymph nodes. Different animals displayed commonly shared TCR clones following 1V270 therapy. Intranasal administration of 1V270 also suppressed lung metastasis and induced tumor-specific adaptive immune responses. These results indicate that systemic 1V270 therapy can induce tumor-specific cytotoxic T cell responses to pulmonary metastatic cancers and that TCR repertoire analyses can be used to monitor, and to predict, the response to therapy.

Quantitative T-cell repertoire analysis of peripheral blood mononuclear cells from lung cancer patients following long-term cancer peptide vaccination.

Therapeutic cancer peptide vaccination is an immunotherapy designed to elicit cytotoxic T-lymphocyte (CTL) responses in patients. A number of therapeutic vaccination trials have been performed, nevertheless there are only a few reports that have analyzed the T-cell receptors (TCRs) expressed on tumor antigen-specific CTLs. Here, we use next-generation sequencing (NGS) to analyze TCRs of vaccine-induced CTL clones and the TCR repertoire of bulk T cells in peripheral blood mononuclear cells (PBMCs) from two lung cancer patients over the course of long-term vaccine therapy. In both patients, vaccination with two epitope peptides derived from cancer/testis antigens (upregulated lung cancer 10 (URLC10) and cell division associated 1 (CDCA1)) induced specific CTLs expressing various TCRs. All URLC10-specific CTL clones tested showed Ca2+ influx, IFN-γ production, and cytotoxicity when co-cultured with URLC10-pulsed tumor cells. Moreover, in CTL clones that were not stained with the URLC10/MHC-multimer, the CD3 ζ chain was not phosphorylated. NGS of the TCR repertoire of bulk PBMCs demonstrated that the frequency of vaccine peptide-specific CTL clones was near the minimum detectable threshold level. These results demonstrate that vaccination induces antigen-specific CTLs expressing various TCRs at different time points in cancer patients, and that some CTL clones are maintained in PBMCs during long-term treatment, including some with TCRs that do not bind peptide/MHC-multimer.

Marmosets (Callithrix jacchus) as a non-human primate model for evaluation of candidate dengue vaccines: induction and maintenance of specific protective immunity against challenges with clinical isolates.

Dengue virus (DENV) is one of the major infectious diseases in tropical regions and approximately half of the world population is at risk of infection. Vaccines would offer an effective control measure against this disease. We previously reported on the utility of marmosets as an animal model for studying primary and secondary dengue infections. Infected marmosets consistently develop viraemia and antibody kinetics that reflect those of patients with dengue. Thus, it is important to determine the utility of marmosets as an animal model for demonstrating vaccine efficacy. In this study, marmosets were inoculated with candidate vaccine and parent strains and challenged with a clinical DENV strain. The viraemia and antibody kinetics in these marmosets were determined. Marmosets consistently develop lower viraemia with an attenuated vaccine strain. During secondary challenge, the IgM response was delayed, whereas the IgG levels rose rapidly, indicating a secondary antibody response. The neutralizing activities against the homotypic serotype were high; all marmosets were protected against viraemia following secondary inoculation. The viraemia markers and antibody responses were consistent with those of human DENV infection and vaccinees. These results demonstrate the utility of marmosets as an animal model for the study of vaccine efficacy.

Fexofenadine Suppresses Delayed-Type Hypersensitivity in the Murine Model of Palladium Allergy.

Palladium is frequently used in dental materials, and sometimes causes metal allergy. It has been suggested that the immune response by palladium-specific T cells may be responsible for the pathogenesis of delayed-type hypersensitivity in study of palladium allergic model mice. In the clinical setting, glucocorticoids and antihistamine drugs are commonly used for treatment of contact dermatitis. However, the precise mechanism of immune suppression in palladium allergy remains unknown. We investigated inhibition of the immune response in palladium allergic mice by administration of prednisolone as a glucocorticoid and fexofenadine hydrochloride as an antihistamine. Compared with glucocorticoids, fexofenadine hydrochloride significantly suppressed the number of T cells by interfering with the development of antigen-presenting cells from the sensitization phase. Our results suggest that antihistamine has a beneficial effect on the treatment of palladium allergy compared to glucocorticoids.

A new high-throughput sequencing method for determining diversity and similarity of T cell receptor (TCR) α and ß repertoires and identifying potential new invariant TCR α chains.

BACKGROUND: High-throughput sequencing of T cell receptor (TCR) genes is a powerful tool for analyses of antigen specificity, clonality and diversity of T lymphocytes. Here, we developed a new TCR repertoire analysis method using 454 DNA sequencing technology in combination with an adaptor-ligation mediated polymerase chain reaction (PCR). This method allows the amplification of all TCR genes without PCR bias. To compare gene usage, diversity and similarity of expressed TCR repertoires among individuals, we conducted next-generation sequencing (NGS) of TRA and TRB genes in peripheral blood mononuclear cells from 20 healthy human individuals. RESULTS: From a total of 267,037 sequence reads from 20 individuals, 149,216 unique sequence reads were identified. Preferential usage of several V and J genes were observed while some recombinations of TRAV with TRAJ appeared to be restricted. The extent of TCR diversity was not significantly different between TRA and TRB, while TRA repertoires were more similar between individuals than TRB repertoires were. The interindividual similarity of TRA depended largely on the frequent presence of shared TCRs among two or more individuals. A publicly available TRA had a near-germline TCR with a shorter CDR3. Notably, shared TRA sequences, especially those shared among a large number of individuals', often contained TCRα related with invariant TCRα derived from invariant natural killer T cells and mucosal-associated invariant T cells. CONCLUSION: These results suggest that retrieval of shared TCRs by NGS would be useful for the identification of potential new invariant TCRα chains. This NGS method will enable the comprehensive quantitative analysis of TCR repertoires at a clonal level.

Genomic sequence analysis of the MHC class I G/F segment in common marmoset (Callithrix jacchus).

The common marmoset (Callithrix jacchus) is a New World monkey that is used frequently as a model for various human diseases. However, detailed knowledge about the MHC is still lacking. In this study, we sequenced and annotated a total of 854 kb of the common marmoset MHC region that corresponds to the HLA-A/G/F segment (Caja-G/F) between the Caja-G1 and RNF39 genes. The sequenced region contains 19 MHC class I genes, of which 14 are of the MHC-G (Caja-G) type, and 5 are of the MHC-F (Caja-F) type. Six putatively functional Caja-G and Caja-F genes (Caja-G1, Caja-G3, Caja-G7, Caja-G12, Caja-G13, and Caja-F4), 13 pseudogenes related either to Caja-G or Caja-F, three non-MHC genes (ZNRD1, PPPIR11, and RNF39), two miscRNA genes (ZNRD1-AS1 and HCG8), and one non-MHC pseudogene (ETF1P1) were identified. Phylogenetic analysis suggests segmental duplications of units consisting of basically five (four Caja-G and one Caja-F) MHC class I genes, with subsequent expansion/deletion of genes. A similar genomic organization of the Caja-G/F segment has not been observed in catarrhine primates, indicating that this genomic segment was formed in New World monkeys after the split of New World and Old World monkeys.

Possible Immune Regulation of Natural Killer T Cells in a Murine Model of Metal Ion-Induced Allergic Contact Dermatitis.

Metal often causes delayed-type hypersensitivity reactions, which are possibly mediated by accumulating T cells in the inflamed skin, called irritant or allergic contact dermatitis. However, accumulating T cells during development of a metal allergy are poorly characterized because a suitable animal model is unavailable. We have previously established novel murine models of metal allergy and found accumulation of both metal-specific T cells and natural killer (NK) T cells in the inflamed skin. In our novel models of metal allergy, skin hypersensitivity responses were induced through repeated sensitizations by administration of metal chloride and lipopolysaccharide into the mouse groin followed by metal chloride challenge in the footpad. These models enabled us to investigate the precise mechanisms of the immune responses of metal allergy in the inflamed skin. In this review, we summarize the immune responses in several murine models of metal allergy and describe which antigen-specific responses occur in the inflamed skin during allergic contact dermatitis in terms of the T cell receptor. In addition, we consider the immune regulation of accumulated NK T cells in metal ion-induced allergic contact dermatitis.

Qualitative differences in brain-infiltrating T cells are associated with a fatal outcome in mice infected with Japanese encephalitis virus.

Japanese encephalitis (JE) is the most important form of viral encephalitis in Asia. The critical factors determining mortality and severity of JE virus (JEV) infection remain unclear. We identified brain-infiltrating T cells associated with a fatal outcome of JEV infection in mice. Dying mice were defined as those that lost more than 25 % of their body weight by day 13 and died by day 21, while surviving mice were defined as those that lost less than 10 % by day 13, based on the result of the survival time course study. Two groups of five mice that demonstrated brain virus titers of >1 × 10(6) pfu/g were randomly selected from the dying and surviving groups and used in the analyses. Cytokine patterns in brains were first examined, revealing a higher ratio of Th1-related cytokine genes in dying mice. The expression levels of CD3, CD8, CD25, and CD69 increased in JEV-infected mice relative to mock-infected mice. However, expression levels of these cell-surface markers did not differ between the two groups. T-cell receptor (TCR) usage and complementary determining region 3 (CDR3) sequences were analyzed in the brain-infiltrating T cells. T cells expressing VA8-1, VA10-1, and VB2-1 increased in both groups. However, the dominant T-cell clones as defined by CDR3 amino acid sequence differed between the two groups. The results indicate that the outcome of JEV infection, death or survival, was determined by qualitative differences in infiltrating T-cell clones with unique CDR3 amino acid sequences.

Accumulation of invariant NKT cells into inflamed skin in a novel murine model of nickel allergy.

Nickel (Ni) can cause delayed-type hypersensitivity reactions, which are thought to be mediated by the accumulation of T cells into inflamed skin. Accumulated T cells at the developmental stages in metal allergy are poorly characterized because a suitable animal model has not been established. To investigate the accumulated T cells in allergic inflamed skin, we generated a novel murine model of Ni-induced allergy. The murine model of Ni allergy was induced by two sensitizations of Ni plus lipopolysaccharide solution into the groin followed by three challenges with Ni solution into the footpad. Here we show that a specific TCR repertoire bearing Vα14Jα18, called natural killer (NK) T cells, was expanded monoclonally in BALB/c or C57BL/6 mice. Accumulation of NKT cells was characterized as CD4(+) or CD4(-)CD8(-) T cells. These results suggested that NKT cells are major pathogenic T cells at the elicitation phase of Ni allergy.

High clonality of virus-specific T lymphocytes defined by TCR usage in the brains of mice infected with West Nile virus.

It has been reported that brain-infiltrating T lymphocytes play critical roles in the clearance of West Nile virus (WNV) from the brains of mice. We characterized brain-infiltrating T lymphocytes by analyzing the TCR α- and ß-chain repertoires, T cell clonality, and CDR3 sequences. CD3(+)CD8(+) T cells were localized in the WNV-infected brains. The expression of CD3, CD8, CD25, CD69, perforin, and granzymes positively correlated with viral RNA levels, and high levels of expression of IFN-γ, TNF-α, and IL-2 were detected in the brains, suggesting that Th1-like cytotoxic CD8(+) T cells are expanded in the brains in response to WNV infection. The brain-infiltrating T lymphocytes dominantly used TCR genes, VA1-1, VA2-1, VB5-2, and VB8-2, and exhibited a highly oligoclonal TCR repertoire. Interestingly, the brain-infiltrating T lymphocytes had different patterns of TCR repertoire usages among WNV-, Japanese encephalitis virus-, and tick-borne encephalitis virus-infected mice. Moreover, CD8(+) T cells isolated from the brains of WNV-infected mice produced IFN-γ and TNF-α after in vitro stimulation with peritoneal cells infected with WNV, but not with Japanese encephalitis virus. The results suggest that the infiltrating CD8(+) T cells were WNV-specific, but not cross-reactive among flaviviruses. T cells from the WNV-infected brains exhibited identical or similar CDR3 sequences in TCRα among tested mice, but somewhat diverse sequences in TCRß. The results indicate that WNV-specific CD3(+)CD8(+) T cells expanding in the infected brains are highly oligoclonal, and they suggest that TCR α-chains play a dominant and critical role in Ag specificity of WNV-specific T cells.

Increased positive selection pressure within the complementarity determining regions of the T-cell receptor ß gene in New World monkeys.

Because of the long-term co-evolution of TCR and MHC molecules, numerous nucleotide substitutions have accumulated within the domains of TCRß genes. We previously found that nonsynonymous nucleotide substitutions occurred more frequently in complementarity determining region (CDR)ß than in CDRα, even though only a limited number of common marmoset (Callithrix jacchus) and human T-cell receptor ß variable (TRBV) sequences were compared. This interesting finding raised the question of whether the increased selective pressure within CDRß was species-specific. In this study, we identified 21 TRBV region sequences from the common marmoset and performed comparative sequence analyses of the T-cell receptor α variable (TRAV) and TRBV regions from human, chimpanzee, rhesus monkey, cotton-top tamarin, Ma's night monkey, and common marmoset. The ratios of the number of nonsynonymous nucleotide substitutions per site (d(N) ) to the d(S) values (d(N) /d(S) ) were less than 1 within the framework regions (FRs) of TRAV and TRBV region sequences, suggesting that purifying selection is largely dominant within the FRs. In contrast, the d(N) values were statistically significantly greater for CDRß than for CDRα only in New World monkeys. Also, increased d(N) /d(S) ratios (d(N) /d(S) >1) were observed within CDRß between humans and New World monkeys and, interestingly, between New World monkeys, which share a relatively recent common ancestor. Moreover, phylogenetic analysis by maximum likelihood analysis provided firm evidence to support that positive selection occurred within CDRß along New World monkey lineages. These results suggest that increased positive selection pressure within CDRß is common in New World monkeys rather than being species-specific. This study provides an intriguing insight into the co-evolution of TCR and MHC molecules within primates.

Comprehensive analysis and characterization of the TCR alpha chain sequences in the common marmoset.

The common marmoset (Callithrix jacchus) is useful as a nonhuman primate model of human diseases. Although the marmoset model has great potential for studying autoimmune diseases and immune responses against pathogens, little information is available regarding the genes involved in adaptive immunity. Here, we identified one TCR alpha constant (TRAC), 46 TRAJ (joining), and 35 TRAV (variable) segments from marmoset cDNA. Marmoset TRAC, TRAJ, and TRAV shared 80%, 68-100%, and 79-98% identity with their human counterparts at the amino acid level, respectively. The amino acid sequences were less conserved in TRAC than in TCRbeta chain constant (TRBC). Comparative analysis of TRAV between marmosets and humans showed that the rates of synonymous substitutions per site (d(S)) were not significantly different between the framework regions (FRs) and complementarity determining regions (CDRs), whereas the rates of nonsynonymous substitutions per site (d(N)) were significantly lower in the FRs than in CDRs. Interestingly, the d(N) values of the CDRs were greater for TRBV than TRAV. These results suggested that after the divergence of Catarrhini from Platyrrhini, amino acid substitutions were decreased in the FRs by purifying selection and occurred more frequently in CDRbeta than in CDRalpha by positive selection, probably depending on structural and functional constraints. This study provides not only useful information facilitating the investigation of adaptive immunity using the marmoset model but also new insight into the molecular evolution of the TCR heterodimer in primate species.

T-cell receptor repertoire of cytomegalovirus-specific cytotoxic T-cells after allogeneic stem cell transplantation.

Cytomegalovirus (CMV) infection is a major complication during allogeneic stem cell transplantation (allo-SCT). However, mechanisms of adaptive immunity that drive this remain unclear. To define early immunological responses to CMV after transplantation, we using next-generation sequencing to examine the repertoire of T-cell receptors in CD8+/CMV pp65 tetramer+ cells (CMV-CTLs) in peripheral blood samples obtained from 16 allo-SCT recipients with HLA-A*24:02 at the time of CMV reactivation. In most patients, TCR beta repertoire of CMV-CTLs was highly skewed (median Inverse Simpson's index: 1.595) and, 15 of 16 patients shared at least one TCR-beta clonotype with ≥ 2 patients. The shared TCRs were dominant in 12 patients and, two clonotypes were shared by about half of the patients. Similarity analysis showed that CDR3 sequences of shared TCRs were more similar than unshared TCRs. TCR beta repertoires of CMV-CTLs in 12 patients were also analyzed after 2-4 weeks to characterize the short-term dynamics of TCR repertoires. In ten patients, we observed persistence of prevailing clones. In the other two patients, TCR repertoires became more diverse, major clones declined, and new private clones subsequently emerged. These results provided the substantive clue to understand the immunological behavior against CMV reactivation after allo-SCT.

Epstein-Barr virus-related diffuse large B-cell lymphoma in mogamulizumab-treated adult T-cell leukemia with incomplete T-cell reconstitution.

Adult T-cell leukemia (ATL) is an aggressive mature T-cell malignancy with a poor prognosis. The anti-C-C motif chemokine receptor 4 (CCR4) antibody mogamulizumab (moga) reduces ATL cells and induces reconstitution of polyclonal T cells; however, ATL cases often remain resistant and moga sometimes causes fatal immunopathology. Epstein-Barr virus (EBV)-related B-cell lymphoma develops in severely immunocompromised subjects, and is particularly associated with impaired T-cell immunity. Here, we report an ATL patient who had received conventional chemotherapy plus moga, and subsequently developed EBV-related diffuse large B-cell lymphoma (DLBCL) of the central nervous system. Next-generation sequencing-based T-cell receptor repertoire analyses identified residual abnormal clones and revealed that reconstitution of polyclonal T cells was incomplete, even after moga treatment. Furthermore, a skin rash that developed after moga treatment was found to contain ATL clones. This case suggests that the limited therapeutic effects of moga and incomplete T-cell reconstitution are associated with severely impaired T-cell immunity and subsequent development of EBV-related DLBCL.

High-throughput sequencing of IgG B-cell receptors reveals frequent usage of the rearranged IGHV4-28/IGHJ4 gene in primary immune thrombocytopenia.

Primary immune thrombocytopenia (ITP) is an acquired form of thrombocytopenia caused by IgG anti-platelet autoantibodies and represents an organ-specific autoimmune disorder. Although the glycoprotein (GP)IIb/IIIa and GPIb/IX have been shown to be targets for autoantibodies, the antigen specificity of autoantibodies is not fully elucidated. To identify the characteristics of IgG B-cell receptor (BCR) repertoires in ITP, we took advantage of adaptor-ligation PCR and high-throughput DNA sequencing methods for analyzing the clone-based repertoires of IgG-expressing peripheral blood B cells. A total of 2,009,943 in-frame and 315,469 unique reads for IGH (immunoglobulin heavy) were obtained from twenty blood samples. Comparison of the IGHV repertoires between patients and controls revealed an increased usage of IGHV4-28 in ITP patients. One hundred eighty-six distinct IGHV4-28-carrying sequences were identified in ITP patients and the majority of these clones used an IGHJ4 segment. The IGHV4-28/IGHJ4-carrying B-cell clones were found in all ITP patients. Oligoclonal expansions of IGHV4-28/IGHJ4-carrying B cells were accompanied by multiple related clones with single amino substitution in the CDR3 region suggesting somatic hypermutation. Taken together, the expansion of IGHV4-28/IGHJ4-carrying IgG-expressing B cells in ITP may be the result of certain antigenic pressure and may provide a clue for the immune pathophysiology of ITP.

Accumulation of T-cells with selected T-cell receptors in the brains of Japanese encephalitis virus-infected mice.

Japanese encephalitis is a severe central nervous system (CNS) disease with a high case fatality rate in humans. We characterized T-cells infiltrating the brain after infection with Japanese encephalitis virus (JEV) in a mouse model and determined the clonality of the infiltrating T-cells by analyzing the sequences of complementary determining region 3 (CDR3) of the T-cell receptor. C3H/He mice died after intraperitoneal infection with the JaTH160 strain of JEV, demonstrating CNS degeneration and prominent T-cell infiltration. The percentages of T-cells bearing the VA5-1, VA17-1, VA19-1, VB2-1, VB8-3 and VB13-1 subfamilies were significantly increased following infiltration of the brains in infected mice. Additionally, CDR3 size spectratyping revealed the oligoclonality in T-cells bearing VA11-1 and VA18-1. CDR3 amino acid sequences were then determined for the VA5-1, VA11-1, VA18-1, VB8-3 and VB13-1 subfamilies. There were high levels of identity and similarity in amino acid sequences of CDR3 in these T-cells. Quantitative real-time PCR analysis also revealed that CD8, interferon-gamma and tumor necrosis factor-alpha were highly expressed in the infected mouse brain. These results indicate that T-cells with high clonality and similarity infiltrate the JEV-infected mouse brain, and that these T-cells are mainly CD8-positive and have the Th1/Tc1 phenotype.