Center for Infectious Disease and Vaccine Research, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655, USA
Correspondence
Masanori Terajima
Masanori.Terajima{at}umassmed.edu
![]() |
ABSTRACT |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Present address: Department of Veterinary Microbiology, Faculty of Agriculture, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan.
Present address: Medical Biology 2, Discovery Research Laboratories, Shionogi & Co. Ltd, 2-5-1, Mishima, Settsu-shi, Osaka 566-0022, Japan.
![]() |
INTRODUCTION |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
At autopsy, endothelial cells in HPS patients' lungs are infected with SNV, but are not necrotic (Nolte et al., 1995; Zaki et al., 1995
). HPS patients have very high levels of viraemia at the onset of pulmonary oedema and then rapidly clear virus from plasma, but pulmonary damage persists (Terajima et al., 1999
). These data suggest that the endothelial cells are not directly injured by the cytopathic effect of viral infection. In HPS patients' lungs, CD8+ T cells are present in infiltrated alveolar walls (Zaki et al., 1995
). A link has been reported between the fatal outcome in HPS and the HLA-B35 allele (Koster et al., 1998
). We isolated several SNV-specific cytotoxic T lymphocyte (CTL) lines restricted by HLA-B35 from HPS patients' blood (Ennis et al., 1997
), and tetramer staining using the CTL epitopes specific for SNV showed that patients with severe HPS have higher frequencies of peptide-specific CD8+ T cells in their blood than patients with moderate HPS (Kilpatrick et al., 2004
). These results suggest that CD8+ CTLs specific for SNV may play a key role in pathogenicity of SNV to humans.
The natural host of SNV is known to be the deer mouse, Peromyscus maniculatus. The experimental infection of deer mice with SNV showed that virus replication was persistent over 90 days, but no apparent clinical symptom was observed (Botten et al., 2000). Syrian hamsters infected with Andes virus and Maporal virus, but not SNV, were found to develop disease similar to HPS (Hooper et al., 2001
; Milazzo et al., 2002
). On the other hand, CTLs in HTN-infected mice play an important role in protection and recovery from persistent infection (Araki et al., 2003
; Asada et al., 1988
; Nakamura et al., 1985a
, b
). Although CTLs induced by HTN or Seoul virus (SEO) infection are cross-reactive, HTN infection induced a higher CTL response than SEO infection in spite of similar levels of antibody responses to these viruses and virus replication (Asada et al., 1989
). SEO is less pathogenic in humans than HTN, suggesting that the difference in CTL induction might influence their pathogenicity. Although H-2Kb-restricted CTL epitopes specific for HTN have been reported (Park et al., 2000
), CTL responses to hantavirus infections including SNV in rodents have not been studied in much detail. Recently, Araki et al. (2003)
reported that newborn mice infected with HTN developed virus-specific IFN-
-producing CD8+ T cells in the acute phase, but produced little TNF-
. CTL activity of splenocytes was not detectable in these mice, suggesting that these virus-specific CD8+ T cells may have been functionally impaired (Araki et al., 2003
).
In order to create a mouse model to study the role of SNV-specific T cells in vivo, we identified mouse CTL epitopes specific for SNV nucleocapsid (N) protein, because it seems to be a major target of human CTL (Ennis et al., 1997), as appears also to be the case for HTN and PUU (Van Epps et al., 1999
, 2002
). We chose H-2b mice (C57BL/6J and B6.PL Thy1a/Cy), since most knockout mice lacking genes involved in immune responses have been made with this genetic background. For immunization of mice with SNV N protein, plasmid DNA or a recombinant vaccinia virus expressing SNV N protein was employed. Next, CTL lines specific for the identified CTL epitopes were established from B6.PL Thy1a/Cy mice (H-2b). Cross-reactivity of the identified epitopes was then compared among SNV, HTN and PUU. These results will enable the analysis of the roles of CTL in pathogenicity of hantaviruses in experimental animal models.
![]() |
METHODS |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Recombinant vaccinia viruses.
Recombinant vaccinia viruses expressing the N protein of SNV or HTN were constructed as described previously (Ennis et al., 1997; Schmaljohn et al., 1990
). These recombinant viruses were grown and titrated in CV1 cells.
Plasmid DNA.
The plasmid pTM1-Nhpsv, carrying the SNV-N protein cDNA (Feldmann et al., 1993), was provided by Christina F. Spiropoulou. The cDNA fragment was amplified by using PCR from pTM1-Nhpsv and cloned into a mammalian expression vector, pcDNA3.1/Hygro() (Invitrogen). For plasmid immunization of mice, the resultant plasmid, pSNVS, was purified using EndoFree Plasmid Giga kit (Qiagen) and then dissolved in 0·85 % saline solution. Expression of SNV N protein from pSNVS was confirmed by immunoprecipitation of pSNVS-transfected COS-7 cells using rabbit anti-SNV serum or a mouse monoclonal antibody specific for hantavirus N protein, GB04-BF07, provided by Patrick C. Stockton and Thomas G. Ksiazek (Ruo et al., 1991
; Zaki et al., 1995
).
Peptides.
Overlapping peptides of SNV, PUU and HTN N proteins were described previously (Ennis et al., 1997; Van Epps et al., 1999
, 2002
). Peptides of SNV, HTN and PUU were based on published sequences of SNV strain NM H10 (accession no. L25784), HTN strain 76118 (M14626) and PUU strain K27 (L08804). Peptides were synthesized at the Protein Chemistry Core Facility at the University of Massachusetts Medical School using an automated Rainin Symphony peptide synthesizer.
Immunization to mice and preparation of splenocytes.
Male B6.PL Thy1a/Cy mice (H-2b; Thy1.2) and C57BL/6J (H-2b; Thy1.1) (46 weeks old) were purchased from Jackson Laboratories (Bar Harbor, ME). Mice were intraperitoneally immunized twice with 2x107 p.f.u. recombinant Vac-SNV-N or wild-type WR strain vaccinia virus at day 0 and 4 weeks. For plasmid injection, mice were intramuscularly injected three times with 100 µg pSNVS in the rear quadriceps at weeks 0, 2 and 4. Seven days after the last immunization, splenocytes were collected, treated with 1x ACK buffer (0·829 % NH4Cl, 0·1 % KHCO3 and 0·0072 % disodium-EDTA) and suspended in RPMI 1640 medium with 10 % heat-inactivated fetal bovine serum (FBS) and 5x105 M 2-mercaptoethanol (2-ME). All mice were kept in the Animal Facility in the University of Massachusetts Medical School, which is regulated by AWA-1995, PHS-1986 and MA140-1985 following the AAALAC-1965 guidelines. Anaesthesia provided by ketamine/xylazine and cervical dislocation, which are consistent with the recommendations of the Panel on Euthanasia of the American Veterinary Medical Association, were used.
In vitro stimulation.
Collected splenocytes were stimulated with 510 µg of each peptide ml1 in RPMI 1640 medium containing 10 % FBS, 5x105 M 2-ME and 25 U recombinant human IL2 ml1. Culture medium was changed twice a week. Bulk culture 51Cr-release assays were performed between days 7 and 12 of culture. For establishment of CTL lines, the cells were stimulated with 2500 rad gamma-irradiated spleen cells from non-immune C57BL/6J mice plus 510 µg ml1 of each peptide every 2 weeks.
CTL lines.
Peptide-specific CTL lines were established by limiting dilution plating. In vitro-stimulated splenocytes were plated at 0·3, 1, 3, 10 or 100 cells per well with 1x106 gamma-irradiated splenocytes pulsed with 5 µg ml1 as feeder cells in a 96-well round-bottom plate (Corning) in 0·2 ml RPMI 1640 with 10 % FBS, 2-ME and human IL2. Medium was replenished twice every week, and wells were restimulated with peptide-pulsed gamma-irradiated feeder cells every 2 weeks. Individual wells were tested for recognition of peptide-pulsed EL-4 cells in a 51Cr-release assay, and positive wells were expanded and restimulated as described above. Surface expression of CD4 and CD8 was determined by flow cytometry with FITC-conjugated antibodies (BD Pharmingen).
51Cr-release assay.
Target cells were labelled with 0·25 mCi (9·25 MBq) 51Cr for 60 min at 37 °C. Following labelling, the cells were washed three times and then resuspended at 4x104 ml1 in RPMI 1640 containing 10 % FBS. Effector cells were added to 2x103 target cells per well pulsed with 0·110 µg peptide ml1 in 96-well round-bottom plates at various effector cell : target cell (E : T) ratio. Plates were incubated for 4·5 h at 37 °C, supernatants were harvested (Skatron Instruments) and specific lysis was calculated as (experimental release spontaneous release)/(maximum release spontaneous release)x100 (%). All assays were performed in triplicate. All experiments were performed at least twice. Spontaneous lysis was less than 15 % in all assays.
Enzyme-linked immunospot (ELISPOT) assay for single-cell IFN- secretion.
ELISPOT assays were performed according to the manufacturer's protocol (Mabtech AB). Briefly, 96-well Multiscreen-IP plates (Millipore) were coated with 15 µg rat anti-mouse IFN- monoclonal antibody (AN-18) ml1 overnight at 4 °C. Freshly isolated splenocytes were then incubated with or without 4 µg peptide ml1 or 5 µg concanavalin A (ConA) ml1 at 37 °C for 2 h and added to the pre-coated plates at 2·5x105 or 5x105 cells per well in RPMI 1640 containing 10 % FBS. Plates were incubated for 1820 h at 37 °C. Biotinylated rat anti-mouse IFN-
monoclonal antibody (R4-6A2) was added and incubated for 2 h at room temperature, followed by the addition of streptavidinhorseradish peroxidase for 12 h at room temperature. Spots were stained with Vector NovaRED substrate kit for peroxidase (Vector Laboratories). The precursor frequency was calculated as (no. of spots in experimental well no. of spots in medium-control well)/(total no. of cells per well). Experiments were performed in duplicate or triplicate wells.
![]() |
RESULTS |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
|
Identification of peptides inducing IFN- production by ELISPOT assay
To identify peptides that induced IFN- production, a library of 69 peptides (15-mer) (without NC217231) was analysed in IFN-
ELISPOT assays. The results showed that at least one peptide, NC175189, induced significant numbers of IFN-
-producing cells (39 cells per 106 splenocytes). However, peptide NC91105 containing NC94101 did not induce a significant number of IFN-
-producing cells (2 cells per 106 splenocytes).
To confirm whether these identified peptides were recognized by T cells, CTL and ELISPOT assays using these three 15-mer peptides and NC94101 were performed (Table 2). C57BL/6J mice were intraperitoneally immunized with 2x107 p.f.u. of Vac-SNV-N twice and splenocytes were collected 15 days after the second immunization. EL-4 cells pulsed with NC175189 were specifically killed by splenocytes stimulated with this peptide (20·7 %) and this peptide also induced the largest number of IFN-
-producing cells (82·3 cells per 106 splenocytes) of all of the peptides (Table 2
). Although NC217231, NC331345 and NC94101 induced fewer IFN-
-producing cells (12·5, 4·3 and 1·1 cells per 106 splenocytes, respectively) than NC175189, EL-4 cells pulsed with these peptides were specifically lysed by splenocytes stimulated in the bulk culture with the respective peptides (22·5, 14·9 and 22·0 %, respectively). Therefore, these three 15-mer peptides and NC94101 appeared to contain epitopes recognized by CTL.
|
|
|
MHC class I restriction of recognition by CTL lines
We studied the MHC class I restriction of recognition by the CTL lines using target cells expressing only one of the H-2b class I genes. The CTL line to NC175189 recognized peptide-pulsed L-Db cells expressing the H-2Db antigen (Table 5). On the other hand, the CTL line to NC217231 killed only peptide-pulsed target cells expressing H-2Kb. In addition, the CTL line to NC331345 significantly killed peptide-pulsed L-Db target cells expressing H-2Db, but there was high non-specific killing activity to peptide-pulsed Jurkat and Jurkat Kb-1 cells (approximately 20 %) (data not shown).
|
|
|
|
![]() |
DISCUSSION |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Panels of human CTL lines specific for SNV, HTN and PUU have been established from patients or convalescent donors and characterized (Ennis et al., 1997; Terajima et al., 2002
; Van Epps et al., 1999
, 2002
). Three T-cell epitopes were identified on the SNV N protein (Ennis et al., 1997
). In HTN and PUU, bulk culture of PBMC from all three HTN and 7 of 13 PUU donors, showed high CTL activity to N protein-expressing cells (Van Epps et al., 1999
, 2002
), suggesting that the N proteins of hantaviruses may be a major target of CTLs in humans. Most of the human CTL epitopes of SNV and PUU, in spite of different HLA restriction, are located in a central region of the N protein (from aa 173 to 251). It is interesting that the two major murine CTL epitopes of SNV, H-2Db-restricted NC180188 and H-2Kb-restricted NC218226, are also located in the central region, indicating that this region might play a key role in inducing CTL activity in humans and mice. When purified PUU N protein was inoculated into H-2d, H-2k or H-2b mice, this same region of N protein was recognized by antibodies from all haplotypes and induced proliferative T-helper lymphocyte responses (de Carvalho Nicacio et al., 2002
). In addition, we found another important region from aa 328 to 342 that induces CTLs in humans and mice. In this region, there are at least two murine CTL epitopes of HTN, 328LGAFFSIL335 and 332FSILQDMRNTIMASK346, and one murine CTL epitope of SNV, 331FAILQDMRNTI341 (Fig. 1
, Table 4
) (Park et al., 2000
), and one human HLA-A2-restricted CTL epitope of HTN, 334ILQDMRNTI342 (Lee et al., 2002
). Although it is not known why these two regions induce CTL activity in humans and mice, this information may be useful for the development of subunit vaccines to induce immune responses including CTLs in human or mouse populations.
ELISPOT assays showed that, of these four peptides, SNV NC175189 induced the largest number of IFN--producing cells from Vac-SNV-N-immunized mice and NC217331 also induced a significant, but smaller, number of IFN-
-producing cells (Table 2
). However, NC91105 and NC332345 did not induce detectable levels of IFN-
-producing cells in spite of the fact that they induced CTL activity (Table 2
and Fig. 1a
), which may be explained by the difference in incubation time with peptides in these two assays (20 h in ELISPOT assay versus 7 days in 51Cr-release assay). Another possibility is that CTL specific for these two peptides might express cytokines other than IFN-
, for example TNF-
.
Cross-reactivity among hantaviruses using the established CTL lines indicated that three of the four CTL lines recognized the highly variable central part of N proteins, and all of them could recognize target cells pulsed with the corresponding peptides of PUU N, but only one CTL line recognized target cells pulsed with a corresponding peptide of HTN N (Table 6). This result is consistent with the identity of amino acid sequences of CTL epitopes. When a recombinant vaccinia virus expressing HTN N protein was used to immunize hamsters, they were protected from challenge with HTN and SEO, but not PUU (Chu et al., 1995
). de Carvalho Nicatio et al. (2002)
reported that bank voles immunized with purified PUU N protein and Freund's complete adjuvant were completely protected from challenge with PUU and partially protected from challenge with Andes virus, which is similar to SNV. They suggested that cellular immune responses may play a more important role than the humoral immune response in cross-protection elicited by recombinant N protein (de Carvalho Nicacio et al., 2002
). Our present results and previous reports reveal that CTLs specific for SNV N protein are more cross-reactive to PUU N than to HTN N and might be more protective against PUU than HTN infections.
In HTN-immunized mice, the number of IFN--producing cells induced by the peptide HTN NC217231 was very large (over 600 cells per 106 splenocytes) (Fig. 1
), indicating that the H-2Kb-restricted CTL epitope, 221SVIGFLAL228, in this peptide might be immunodominant in CTL induction. The recombinant vaccinia viruses, Vac-SNV-N and Vac-HTN-N, used in this study were based on the WR strain of vaccinia virus, and the recombinant genes were inserted into the thymidine kinase gene locus. However, the HTN and SNV N proteins were transcribed using different promoters, P7.5 and the promoter of the Choristoneura biennis entomopoxvirus spheroidin, respectively. The spheroidin promoter induces significantly higher levels of recombinant protein expression than the P7.5 promoter (Pearson et al., 1991
), suggesting that the HTN N protein might be expressed less in mice than SNV N. However, our ELISPOT assay revealed that HTN N protein seems to induce more IFN-
-producing cells than SNV N protein (Fig. 1
). This result suggests that HTN N protein might induce stronger CTL activity than SNV N protein, irrespective of the amount of protein produced.
Identification of SNV-specific mouse CD8+ T-cell epitopes is necessary to isolate epitope-specific CD8+ T cells from infected mice using mouse MHC class I dimers or tetramers to study their functionality and TCR usage at the single-cell level. It will be interesting to compare epitope-specific CD8+ T cells in the acute phase in newborn and adult mice infected with hantavirus, where differences in CTL activity and TNF- expression were observed (Araki et al., 2003
).
Recently, we showed by MHC class I tetramer staining that patients with severe HPS have larger numbers of SNV-specific CD8+ T cells in their blood than patients with moderate HPS (Kilpatrick et al., 2004). It is possible to induce SNV epitope-specific CD8+ T cells in laboratory mice, isolate and culture them ex vivo, and adoptively transfer them into mice in which the SNV N protein is expressed in pulmonary endothelial cells. When the number of CTLs adoptively transferred into mice is large enough, these CTLs may be able to cause capillary leakage by attacking endothelial cells expressing the N protein. These experiments could clarify the role of CTLs in the pathogenesis of HPS. A similar experimental system has been used to analyse the immunopathological mechanism of interstitial pneumonia caused by influenza A virus infection (Enelow et al., 1998
). Syrian hamsters infected with Andes virus and Maporal virus, but not SNV, were found to develop disease similar to HPS (Hooper et al., 2001
; Milazzo et al., 2002
), but there are few immunological reagents available to analyse cellular immune responses in Syrian hamsters.
The H-2Kb-restricted epitope 94SSLRYGNV101 has typical anchor residues at positions 5 (Y) and 8 (V) (Rammensee et al., 1995), and amino acid changes at positions 2 (S to M) and 4 (R to S) result in the loss of recognition by the specific CTL line (Table 6
). This epitope was respectively the ninth and second highest binding 8-mer peptide to the H-2 Kb molecule predicted by two commonly used MHC-binding motif search programs, HLA Peptide Binding Predictions (http://bimas.dcrt.nih.gov/molbio/hla_bind/) (Parker et al., 1994
) and SYFPEITHI (http://www.syfpeithi.de) (Rammensee et al., 1999
) in the SNV N protein, which is 428 aa long. Another H-2Kb-restricted epitope, 218PVMGVIGFS226, is 9 aa long, instead of 8 aa long typical for H-2Kb-restricted epitopes, and does not have typical anchor residues. Amino acid changes at positions 4 (G to S) and 9 (S to L) result in the loss of recognition by the specific CTL line. This 9-mer epitope was not selected by either HLA Peptide Binding Predictions (it did not have a score greater than 1) or SYFPEITHI (this program does not have 9-mer motif for the H-2 Kb molecule). The H-2Db-restricted epitope 180SMPTAQSTM188 has a typical anchor residue at position 9 (M). An A at position 5 is not a typical anchor residue. Amino acid changes at positions 2, 4 and 8, none of which are at anchor residues, result in loss of recognition by the specific CTL line. This 9-mer epitope was respectively the second and sixth highest binding peptide to the H-2 Db molecule predicted by HLA Peptide Binding Predictions and SYFPEITHI. Identification of these epitopes showed both the usefulness and the limitation of the current MHC-binding motif search programs.
In conclusion, mouse CTL responses to hantaviruses were analysed and defined in this study. The results should be useful for the development of experimental vaccines, the analysis of mechanisms of capillary leakage in HPS model systems and the analysis of the differences in pathogenicity among hantaviruses, including SNV in rodents and humans.
![]() |
ACKNOWLEDGEMENTS |
---|
![]() |
REFERENCES |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Asada, H., Tamura, M., Kondo, K., Dohi, Y. & Yamanishi, K. (1988). Cell-mediated immunity to virus causing haemorrhagic fever with renal syndrome: generation of cytotoxic T lymphocytes. J Gen Virol 69, 21792188.[Abstract]
Asada, H., Balachandra, K., Tamura, M., Kondo, K. & Yamanishi, K. (1989). Cross-reactive immunity among different serotypes of virus causing haemorrhagic fever with renal syndrome. J Gen Virol 70, 819825.[Abstract]
Botten, J., Mirowsky, K., Kusewitt, D., Bharadwaj, M., Yee, J., Ricci, R., Feddersen, R. M. & Hjelle, B. (2000). Experimental infection model for Sin Nombre hantavirus in the deer mouse (Peromyscus maniculatus). Proc Natl Acad Sci U S A 97, 1057810583.
Centers for Disease Control & Prevention (2004). Case Information: Hantavirus Pulmonary Syndrome Case Count and Descriptive Statistics. Atlanta, GA: Centers for Disease Control & Prevention.
Chu, Y. K., Jennings, G., Schmaljohn, A. & 8 other authors (1995). Cross-neutralization of hantaviruses with immune sera from experimentally infected animals and from hemorrhagic fever with renal syndrome and hantavirus pulmonary syndrome patients. J Infect Dis 172, 15811584.[Medline]
de Carvalho Nicacio, C., Gonzalez Della Valle, M., Padula, P., Bjorling, E., Plyusnin, A. & Lundkvist, A. (2002). Cross-protection against challenge with Puumala virus after immunization with nucleocapsid proteins from different hantaviruses. J Virol 76, 66696677.
Duchin, J. S., Koster, F. T., Peters, C. J. & 13 other authors (1994). Hantavirus pulmonary syndrome: a clinical description of 17 patients with a newly recognized disease. The Hantavirus Study Group. N Engl J Med 330, 949955.
Eisenlohr, L. C., Yewdell, J. W. & Bennink, J. R. (1992). A transient transfection system for identifying biosynthesized proteins processed and presented to class I MHC restricted T lymphocytes. J Immunol Methods 154, 131138.[CrossRef][Medline]
Enelow, R. I., Mohammed, A. Z., Stoler, M. H., Liu, A. N., Young, J. S., Lou, Y. H. & Braciale, T. J. (1998). Structural and functional consequences of alveolar cell recognition by CD8+ T lymphocytes in experimental lung disease. J Clin Invest 102, 16531661.
Ennis, F. A., Cruz, J., Spiropoulou, C. F., Waite, D., Peters, C. J., Nichol, S. T., Kariwa, H. & Koster, F. T. (1997). Hantavirus pulmonary syndrome: CD8+ and CD4+ cytotoxic T lymphocytes to epitopes on Sin Nombre virus nucleocapsid protein isolated during acute illness. Virology 238, 380390.[CrossRef][Medline]
Feldmann, H., Sanchez, A., Morzunov, S., Spiropoulou, C. F., Rollin, P. E., Ksiazek, T. G., Peters, C. J. & Nichol, S. T. (1993). Utilization of autopsy RNA for the synthesis of the nucleocapsid antigen of a newly recognized virus associated with hantavirus pulmonary syndrome. Virus Res 30, 351367.[CrossRef][Medline]
Hooper, J. W., Larsen, T., Custer, D. M. & Schmaljohn, C. S. (2001). A lethal disease model for hantavirus pulmonary syndrome. Virology 289, 614.[CrossRef][Medline]
Jenison, S., Yamada, T., Morris, C., Anderson, B., Torrez-Martinez, N., Keller, N. & Hjelle, B. (1994). Characterization of human antibody responses to four corners hantavirus infections among patients with hantavirus pulmonary syndrome. J Virol 68, 30003006.[Abstract]
Kanerva, M., Mustonen, J. & Vaheri, A. (1998). Pathogenesis of puumala and other hantavirus infections. Rev Med Virol 8, 6786.[CrossRef][Medline]
Kilpatrick, E. D., Terajima, M., Koster, F. T., Catalina, M. D., Cruz, J. & Ennis, F. A. (2004). Role of specific CD8+ T cells in the severity of a fulminant zoonotic viral hemorrhagic fever, hantavirus pulmonary syndrome. J Immunol 172, 32973304.
Koster, F. T., Williams, T. M., Griffith, B. B., Goade, D. E. & Hjelle, B. L. (1998). Genetic associations with hantavirus pulmonary syndrome due to Sin Nombre virus. In The Fourth International Conference on HFRS and Hantaviruses, p. 179. Atlanta, GA, USA.
Kurane, I. & Ennis, F. A. (1994). Cytokines in dengue virus infections: role of cytokines in the pathogenesis of dengue hemorrhagic fever. Semin Virol 5, 443448.[CrossRef]
Lee, K. Y., Chun, E., Kim, N. Y. & Seong, B. L. (2002). Characterization of HLA-A2.1-restricted epitopes, conserved in both Hantaan and Sin Nombre viruses, in Hantaan virus-infected patients. J Gen Virol 83, 11311136.
Milazzo, M. L., Eyzaguirre, E. J., Molina, C. P. & Fulhorst, C. F. (2002). Maporal viral infection in the Syrian golden hamster: a model of hantavirus pulmonary syndrome. J Infect Dis 186, 13901395.[CrossRef][Medline]
Nakamura, T., Yanagihara, R., Gibbs, C. J., Jr, Amyx, H. L. & Gajdusek, D. C. (1985a). Differential susceptibility and resistance of immunocompetent and immunodeficient mice to fatal Hantaan virus infection. Arch Virol 86, 109120.[Medline]
Nakamura, T., Yanagihara, R., Gibbs, C. J., Jr & Gajdusek, D. C. (1985b). Immune spleen cell-mediated protection against fatal Hantaan virus infection in infant mice. J Infect Dis 151, 691697.[Medline]
Nolte, K. B., Feddersen, R. M., Foucar, K. & 7 other authors (1995). Hantavirus pulmonary syndrome in the United States: a pathological description of a disease caused by a new agent. Hum Pathol 26, 110120.[Medline]
Park, J. M., Cho, S. Y., Hwang, Y. K., Um, S. H., Kim, W. J., Cheong, H. S. & Byun, S. M. (2000). Identification of H-2Kb-restricted T-cell epitopes within the nucleocapsid protein of Hantaan virus and establishment of cytotoxic T-cell clones. J Med Virol 60, 189199.[CrossRef][Medline]
Parker, K. C., Bednarek, M. A. & Coligan, J. E. (1994). Scheme for ranking potential HLA-A2 binding peptides based on independent binding of individual peptide side-chains. J Immunol 152, 163175.
Pearson, A., Richardson, C. & Yuen, L. (1991). The 5' noncoding region sequence of the Choristoneura biennis entomopoxvirus spheroidin gene functions as an efficient late promoter in the mammalian vaccinia expression system. Virology 180, 561566.[CrossRef][Medline]
Rammensee, H.-G., Friede, T. & Stevanovic, S. (1995). MHC ligands and peptide motifs: first listing. Immunogenetics 41, 178228.[Medline]
Rammensee, H.-G., Bachmann, J., Emmerich, N. P. N., Bachor, O. A. & Stevanovic, S. (1999). SYFPEITHI: database for MHC ligands and peptide motifs. Immunogenetics 50, 213219.[CrossRef][Medline]
Rothman, A. L. & Ennis, F. A. (1999). Immunopathogenesis of Dengue hemorrhagic fever. Virology 257, 16.[CrossRef][Medline]
Ruo, S. L., Sanchez, A., Elliott, L. H., Brammer, L. S., McCormick, J. B. & Fisher-Hoch, S. P. (1991). Monoclonal antibodies to three strains of hantaviruses: Hantaan, R22, and Puumala. Arch Virol 119, 111.[Medline]
Schmaljohn, C. & Hjelle, B. (1997). Hantaviruses: a global disease problem. Emerg Infect Dis 3, 95104.[Medline]
Schmaljohn, C. S., Chu, Y. K., Schmaljohn, A. L. & Dalrymple, J. M. (1990). Antigenic subunits of Hantaan virus expressed by baculovirus and vaccinia virus recombinants. J Virol 64, 31623170.[Medline]
Terajima, M., Hendershot, J. D., III, Kariwa, H., Koster, F. T., Hjelle, B., Goade, D., DeFronzo, M. C. & Ennis, F. A. (1999). High levels of viremia in patients with the Hantavirus pulmonary syndrome. J Infect Dis 180, 20302034.[CrossRef][Medline]
Terajima, M., Van Epps, H. L., Li, D., Leporati, A. M., Juhlin, S. E., Mustonen, J., Vaheri, A. & Ennis, F. A. (2002). Generation of recombinant vaccinia viruses expressing Puumala virus proteins and use in isolating cytotoxic T cells specific for Puumala virus. Virus Res 84, 6777.[CrossRef][Medline]
Terajima, M., Vapalahti, O., Epps, H. L. V., Vaheri, A. & Ennis, F. A. (2004). Immune responses to Puumala virus infection and the pathogenesis of nephropathia epidemica. Microbes Infect 6, 238245.[CrossRef][Medline]
Van Epps, H. L., Schmaljohn, C. S. & Ennis, F. A. (1999). Human memory cytotoxic T-lymphocyte (CTL) responses to Hantaan virus infection: identification of virus-specific and cross-reactive CD8+ CTL epitopes on nucleocapsid protein. J Virol 73, 53015308.
Van Epps, H. L., Terajima, M., Mustonen, J., Arstila, T. P., Corey, E. A., Vaheri, A. & Ennis, F. A. (2002). Long-lived memory T lymphocyte responses after hantavirus infection. J Exp Med 196, 579588.
Zaki, S. R., Greer, P. W., Coffield, L. M. & 7 other authors (1995). Hantavirus pulmonary syndrome. Pathogenesis of an emerging infectious disease. Am J Pathol 146, 552579.[Abstract]
Received 31 December 2003;
accepted 2 March 2004.
HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
INT J SYST EVOL MICROBIOL | MICROBIOLOGY | J GEN VIROL |
J MED MICROBIOL | ALL SGM JOURNALS |