Plexiform fibrohistiocytic tumor: A series of 10 case studies.

OBJECTIVES: We sought to investigate the clinicopathologic features and differential diagnosis of plexiform fibrohistiocytic tumor (PFHT) and its pathogenesis. METHODS: Ten cases of PFHT were collected from Xi Jing Hospital, Fourth Military Medical University, from September 2008 to December 2022 for clinical data as well as microscopic and immunohistochemical observation. CCND1 gene amplification and break were assayed by fluorescence in situ hybridization (FISH). RESULTS: We report 10 cases of PFHT according to histologic classification. Seven cases were of histiocytoid type, and 3 had mucous degeneration in the nodules. One case was of fibroblastic type, which was mainly composed of fibroblast-like cells. Two cases were of mixed type. Immunohistochemically, the osteoclast-like multinucleated giant cells, histiocyte-like cells, and occasional spindle cells in the adjacent fascicles were reactive for CD68 (10/10), CD163 (5/8), CD10 (8/8), cyclin D1 (8/8), CDK4 (5/8), ß-catenin (4/6), MITF (2/6), and PGP9.5 (4/5). Vimentin (9/9) was strongly positive in tumor cells and peripheral fibroblast-like cells. The positive index of Ki-67 was 5% to 40%, with an average of 20%. The FISH analysis showed neither amplification nor break of the CCND1 gene. All cases underwent surgical resection, and patients were followed up for 9 months to 11 years. Only 2 cases recurred. CONCLUSIONS: Plexiform fibrohistiocytic tumor is a low-grade malignant soft tissue neoplasm. The diagnosis mainly depends on histopathologic and immunohistochemical markers. Cyclin D1 and CD10 expression has diagnostic value for the diagnosis and differential diagnosis of PFHT combined with its plexiform morphology. The overexpression of cyclin D1 suggests an involvement of cell cycle regulatory genes in the pathogenesis of PFHT.

Spindle cell variant of medullary thyroid carcinoma: a clinicopathologic study of four cases.

BACKGROUND: Medullary thyroid carcinoma (MTC) is a malignant tumor derived from C cells. It accounts for about 10% of all thyroid malignancies. More than 14 histological variants have been described. Among them, spindle cell variant is extremely rare. CASE PRESENTATION: Here we describe 4 cases of spindle cell variant of MTC collected from 2012 to 2019. Ultrasound showed solid and hypoechoic nodules. Three patients underwent total thyroidectomy and regional lymph node dissection, and 1 patient underwent thyroid mass resection. Histologically, the tumors showed spindle shaped cells in bundles or interlaced arrangement, separated by hyalinised fibrous stroma that contained amyloid deposits. Immunohistochemistry showed that the tumor cells were positive for calcitonin, chromogranin A, synaptophysin, CD56, and TTF-1, but negative for other lineage-specific markers. CONCLUSIONS: We report 4 rare cases of spindle cell variant of MTC. Due to its rarity and special morphology, the diagnosis of spindle cell variant MTC relies on its morphology and immunohistochemical markers to avoid misdiagnosis.

Chronic intermittent hypoxia alters the dendritic mitochondrial structure and activity in the pre-Bötzinger complex of rats.

Mitochondrial bioenergetics is dynamically coupled with neuronal activities, which are altered by hypoxia-induced respiratory neuroplasticity. Here we report structural features of postsynaptic mitochondria in the pre-Bötzinger complex (pre-BötC) of rats treated with chronic intermittent hypoxia (CIH) simulating a severe condition of obstructive sleep apnea. The subcellular changes in dendritic mitochondria and histochemistry of cytochrome c oxidase (CO) activity were examined in pre-BötC neurons localized by immunoreactivity of neurokinin 1 receptors. Assays of mitochondrial electron transport chain (ETC) complex I, IV, V activities, and membrane potential were performed in the ventrolateral medulla containing the pre-BötC region. We found significant decreases in the mean length and area of dendritic mitochondria in the pre-BötC of CIH rats, when compared to the normoxic control and hypoxic group with daily acute intermittent hypoxia (dAIH) that evokes robust synaptic plasticity. Notably, these morphological alterations were mainly observed in the mitochondria in close proximity to the synapses. In addition, the proportion of mitochondria presented with enlarged compartments and filamentous cytoskeletal elements in the CIH group was less than the control and dAIH groups. Intriguingly, these distinct characteristics of structural adaptability were observed in the mitochondria within spatially restricted dendritic spines. Furthermore, the proportion of moderately to darkly CO-reactive mitochondria was reduced in the CIH group, indicating reduced mitochondrial activity. Consistently, mitochondrial ETC enzyme activities and membrane potential were lowered in the CIH group. These findings suggest that hypoxia-induced respiratory plasticity was characterized by spatially confined mitochondrial alterations within postsynaptic spines in the pre-BötC neurons. In contrast to the robust plasticity evoked by dAIH preconditioning, a severe CIH challenge may weaken the local mitochondrial bioenergetics that the fuel postsynaptic activities of the respiratory motor drive.

Primary Osteosarcoma of the Liver: Case Report and Literature Review.

Extraskeletal osteosarcoma is a rare, highly malignant, osteoid formation mesenchymal neoplasm in the absence of bone involvement, associated with exceptionally poor prognosis. It frequently arises in the soft tissues of the extremities or in the retroperitoneum, but rarely in visceral organ. We describe a primary osteosarcoma of the liver in a 70-year-old man who presented with an episode of fever, accompanied by abdominal discomfort, after an accident abdominal strike. Ultrasonography and computed tomography revealed a large heterogeneous mass with areas of dense calcification involving most of the right lobe of liver. Radiography did not show evidence of primary tumor or primary bone lesion at any other site. Histologically, the tumor showed an essentially similar appearance as osteosarcoma originating in the skeleton, comprised of polygonal or spindle shaped cells, along with abundant eosinophilic lace-like osteoids, or irregularly arranged bone trabeculae. Immunohistochemistry showed that the tumor cells were positive for vimentin, CD10, and focally for SMA and CD56, but negative for other lineage-specific markers. Thus, the findings favored a primary hepatic osteosarcoma. This patient received palliative chemotherapy to ease the signs of his sickness due to the large size of the tumor and he died 4 moths later.

Catecholaminergic neurons in synaptic connections with pre-Bötzinger complex neurons in the rostral ventrolateral medulla in normoxic and daily acute intermittent hypoxic rats.

The rostral ventrolateral medulla (RVLM) contains cardiovascular-related catecholaminergic neurons and respiratory-related pre-Bötzinger complex (pre-BötC) neurons, which are intermingled and functionally connected for coordinating cardiorespiratory activities. Daily acute intermittent hypoxia (dAIH) is known to elicit respiratory plasticity. However, it is unclear if the catecholaminergic neurons directly synapse onto pre-BötC neurons, and if the local circuitry exhibits plasticity when exposed to dAIH. The present study was aimed to determine the synaptic phenotypes between dopamine-ß-hydroxylase (DßH)-immunoreactive (ir) catecholaminergic neurons and neurokinin 1 receptor (NK1R)-ir pre-BötC neurons, and the effect of dAIH on the neuronal network. Immunofluorescence histochemistry was used to reveal immunoreactivities of DßH and NK1R in the RVLM of normoxic and dAIH rats. Synaptic phenotypes were examined with double-labeling immunoelectron microscopy. We found that DßH immunoreactivity was expressed in somata and processes, some of which were in close apposition to NK1R-ir pre-BötC neurons. DßH-ir gold particles were localized to somata, dendrites, and axonal terminals. DßH-ir terminals formed asymmetric synapses, and occasionally, symmetric synapses in the pre-BötC, featuring the local circuitry. Of the synapses, 28% in normoxic and 29.6% in dAIH groups were apposed to NK1R-ir dendrites. Significant increases in DßH expression and NK1R-ir processes were found in the dAIH group. Moreover, the area and number of processes in close appositions were significantly elevated, strongly suggesting that dAIH induced plasticity with increased connections and interactions between the cardiovascular- and respiratory-related neurons in the local circuitry. In conclusion, asymmetric synapses are predominant in the crosstalk between catecholaminergic and pre-BötC neurons in the RVLM, elaborating excitatory transmission driving the coupling of cardiorespiratory activities. The neural network manifests plasticity in response to dAIH challenge.

Sarcomatoid variant of ALK- anaplastic large cell lymphoma involving multiple lymph nodes and both lungs with production of proinflammatory cytokines: report of a case and review of literature.

Sarcomatoid variant of anaplastic large cell lymphoma (ALCL) is one of the rarest histologic variants of ALCL that consists of large, bizarre, often spindle-shaped, neoplastic cells resembling a soft tissue sarcoma. We report here such a case of ALCL with both pulmonary and multiple nodal involvement in a 47-year-old woman who initially presented with fever, cough, sputum, itching skin, and weight loss. The initial transbronchial lung biopsy showed discohesive pleomorphic malignant cells in a strong inflammatory milieu reminiscent of inflammatory malignant fibrous histiocytoma (MFH). Subsequent cervical lymph node biopsy revealed a spindle cell sarcoma predominantly composed of plump spindle and oval neoplastic cells in interweaving fascicles, with sparse inflammatory infiltrates, resembling pleomorphic-storiform type of MFH. However, these tumor cells in the lung and node lesions revealed essentially similar immunohistochemical features that were positive for CD30, EMA, TIA-1, granzyme B, and fascin, but negative for anaplastic lymphoma kinase (ALK), and T- or B-lineage-specific marker. The spindled cells stains diffuse strong positive for smooth muscle actin (SMA), along with vimentin. Further studies showed that the tumor produced large quantities of the proinflammatory cytokines interleukin-2 (IL-2), IL-6, and IL-8, which we believe may contribute to the pathogenesis of sarcomatoid transformation of this tumor, and was associated with the patient's inflammatory symptoms. To the best of our knowledge, this is the first reported case of sarcomatoid variant of ALK-negative ALCL with null cell phenotype and in situ production of proinflammatory cytokines presenting as multiple nodes and pulmonary involvement.

Spindle cell rhabdomyosarcoma of the retroperitoneum: an unusual case developed in a pregnant woman but obscured by pregnancy.

Spindle cell rhabdomyosarcoma (RMS) is an uncommon histiologic variant of RMS that has spindle cell morphology. This tumor occurs almost exclusively in childhood and more rarely in adults. Only a few adult cases, including two retroperitoneal cases in male patients, have been documented previously. We describe a rare case of spindle cell RMS of the retroperitoneum in a 37-year-old woman developed during pregnancy and incidentally discovered after vaginal delivery. Computed tomography showed a huge tumor mass, measured 20 × 20 × 15 cm in size, arising in retroperitoneal space. Histologically, the tumor consisted of spindle cells arranged in a fascicular or herringbone growth pattern, morphologically mimicking adult fibrosarcoma, intermingled with scattered rhabdomyoblasts. Mitotic activity ranged from 20 to 28 mitoses per 10 high-power fields and tumor necrosis was evident. Immunohistochemically, tumor cells were stained diffusely positive for muscle specific actin, desmin, and vimentin, scattered positive for myogenin, MyoD1 and myoglobin, with a Ki-67 (MIB-1) proliferative labeling index of 46.11%. This tumor also stains positively for CD99, strong cytoplasmic WT1, and nuclear p53. Other markers such as S100 protein, smooth muscle specific actin, CD34, cytokeratin, and epithelial membrane antigen were all negative in the tumor cells. On the basis of the findings, a spindle cell RMS was diagnosed. The neoplasm was incompletely excised because of encasement of major vessels and invasion to adjacent structures, and additional chemotherapy was given.

Clinicopathological and extensive immunohistochemical study of a type II pleuropulmonary blastoma.

Pleuropulmonary blastoma (PPB) is a rare malignant dysontogenetic neoplasm primarily affecting younger children, even in newborns with an unfavorable outcome. PPB is histologically composed of a primitive, variably mixed blastematous and sarcomatous components, and exclusively subclassified as type I (purely cystic), type II (both cystic and solid elements) and type III (completely solid) by increasing histological evidence of malignancy. At present, well-documented cases or cases of truly precise presentation of either pathological or immunohistochemical findings in PPB are rare. The authors report one case of PPB in a 44-month-old child presenting as a solid and cystic mass with special emphasis on its radiological, histopathological and immunohistochemical aspects. The histological diagnosis was PPB, which would belong to the type II category.

Abnormal expression of NRF-2α in hepatocellular carcinoma identified with a newly prepared monoclonal antibody against human NRF-2α protein.

Human nuclear respiratory factor 2 alpha subunit (NRF-2α) is fundamentally important to cell function and the development. We aimed to establish the monoclonal antibody (MAb) against the human NRF-2α protein and to investigate its distribution in human hepatocellular carcinoma (HCC) and tumor-adjacent tissues. The 6× His-NRF-2α fusion protein was successfully induced and purified. One monoclonal antibody (MAb) against human NRF-2α, 1-D10-E1-B11-G3 (IgG1), effective in detecting the recombinant and the cellular protein, was characterized. Using immunohistochemical analysis, the expression of NRF-2α was investigated in 38 cases of HCC specimens and 14 cases of tumor-adjacent specimens. Staining was found positive in 9 cases of HCC tissues (23.7%) and 8 cases of normal hepatic tissues (57.1%). The higher-grade frequency of expression of NRF-2α in tumor-adjacent tissues was significantly higher (P < 0.01) than that in tumor tissues, suggesting that NRF-2α may play important roles in carcinogenesis of HCC.

Primary follicular dendritic cell sarcoma of the thyroid gland coexisting with Hashimoto's thyroiditis.

Follicular dendritic cell (FDC) sarcoma, especially of extranodal origin, is an extremely rare malignancy of FDC origin, with only 1 case previously documented in the thyroid. The authors report the case of a 58-year-old female who presented with a painless mass in her neck. The neoplastic cells expressed monocyte/macrophage-specific marker CD68 (KP-1) and lysozymes and the dendritic cell-associated antigens CD35 and Fascin but was negative for CD1a, CD21, and CD23, most consistent with a diagnosis of FDC sarcoma. BIOMED-2 multiplex polymerase chain reaction analysis showed B-cell clonality in both tumor and its adjacent coexisting Hashimoto's thyroiditis. To the authors' knowledge, this is the first report of a rare entity of FDC sarcoma primarily involving the thyroid gland coexisting with Hashimoto's thyroiditis.

Kaposiform hemangioendothelioma of the spleen in an adult: an initial case report.

Kaposiform hemangioendothelioma (KHE) is a rare locally aggressive vascular neoplasm characterized by infiltrating nodules and sheets of spindle cells, and unmistakable resemblance to Kaposi's sarcoma. KHE occurs mainly in newborns and infants and presents most commonly in the skin, deep soft tissue, and bone. We report a case of KHE in a 36-year-old female who presented with a spleen mass and underwent splenectomy. Macroscopic examination revealed a large, dark-red, firm mass in the spleen. Histologically, the tumor consisted of irregular, infiltrating nodules of densely packed spindle-shaped tumor cells closely associated with small slit-like and sieve-like blood vessels, which were separated with hyalinized hypocellular fibrous stroma. Immunohistochemically, both spindle and epithelioid cells were positive for CD34, CD31, and vimentin, but negative for EMA, cytokeratin, CD21, CD35, CD1a, and S-100 protein. The well-formed capillaries and mature vessels but not spindle tumor cell showed reactivity for factor VIII- related antigen. Alpha-Smooth muscle actin was detected in pericytes surrounding small round or slit-like capillaries. The final histologic diagnosis was KHE. Follow-up 6 month after operation revealed no sign of recurrence or metastasis.To the best of our knowledge, this is the first report of KHE arising in the spleen.

A case of primary histiocytic sarcoma arising from thyroid gland.

Histiocytic sarcoma (HS) is an extremely rare true histiocytic malignancy. We report a case of HS arising from thyroid gland in a 69 year-old man. Following subtotal thyroidectomy, a histopathologic, immunohistologic, and genotypic examination revealed HS. This tumor was composed of large spindle or round epithelioid cells with abundant eosinophilic cytoplasm. The neoplastic cells were positive for macrophage-associated antigen CD68, CD163, and lysozymes, as well as CD45, HLA- DR, DP, DQ, and S100, most consistent with a diagnosis of HS. The BIOMED-2 multiplex PCR analysis showed polyclonal B- and T-cell populations. To our knowledge, this is the first report of a rare entity HS involving thyroid gland using a comprehensive immunophenotyping panel including CD163 as well as molecular studies to establish the true histiocytic nature of these lesions.

HSP70 induced by Hantavirus infection interacts with viral nucleocapsid protein and its overexpression suppresses virus infection in Vero E6 cells.

Hantavirus (HTV) infection is known to induce innate cellular response, a more specified cellular response in the host cells. However, whether it stimulates synthesis of stress proteins, particularly associations of viral proteins, is entirely unknown. The primary focus of this research is using Vero E6 cells infected with Hantaan 76-118 (HTNV) as an in vitro infection model to examine the individual contribution of HTV infection to heat shock response. This study shows that HTNV infection rapidly induced HSP70 expression in Vero E6 cells, which underwent a nucleo-cytoplasmic shuttle that lasted for more than 3 d. The increased HSP70 was preceded by induction of HSP70 mRNA. The physical association of HSP70 with viral nucleocapsid protein (NP) in infected cells was demonstrated by co-localization and immunoprecipation. Vero E6 cells that constitutively overexpress HSP70 after stable transfection with HSP70 gene, when infected with HTNV, showed selectively reduced NP synthesis. These findings suggest HSP70 is actively involved in the control of the expression level of viral structural proteins and possibly involved in virus assembly by binding of NP to HSP70. Overexpression of HSP70 does not favor viral propagation.

[The colocalized relationship between p53 mutants 249M, 273H and hsp70 in HepG2 cells].

AIM: To synthesize p53 mutants 249M, 273H with site-directed mutagenesis and construct the relative GFP expression vectors, transfect HepG2 cells and then detect the co-localization of p53 and hsp70. METHODS: Two sets of primers were designed according to the gene sequence of p53, and mismatches were introduced into primers. Mutagenesis was performed in a two-step PCR. The amplified fragments containing the mutation site from the second PCR were subcloned into the pEGFP-C3 vectors. The localization of p53 and hsp70 was observed in transfected HepG2 cells using confocal microscopy. RESULTS: The sequencing analysis showed that the mutated sites were correct. The expression vectors were constructed successfully. Endogenous hsp70 co-localized in cytoplasm with 273H p53, wt p53 and 249M p53 localized in nucleus. CONCLUSION: We have found p53 and hsp70 positive products were colocalized in nuclei of human HCC, while the endogenous hsp70 were colocalized in cytoplasm with 273H p53 in HepG2 cells. This contradictory phenomenon suggests that perhaps there are unclear mechanisms existed between the relationship of hsp70 and p53.

[Significant increase of glucose transport activity in breast cancer].

OBJECTIVE: To study the expression level and significance of glucose transporter 1 (Glut-1) in normal breast tissue, adenosis, adenoma and breast carcinoma. METHODS: A total of 147 cases of female breast tissue samples, including 92 cases of invasive ductal carcinoma, 26 cases of breast fibroadenoma, 24 cases of breast adenosis and 5 cases of normal breast tissues, were collected for quantitative detection of the expression of Glut-1 protein by immunohistochemistry (EnVision method) and Western blot, and its mRNA by reverse transcriptase-polymerase chain reaction (RT-PCR). RESULTS: In normal breast tissue and benign lesions of the breast, Glut-1 was undetectable or only weakly detectable in cytoplasm of ductal and acinar epithelia. In contrast, the intensity of Glut-1 staining was significantly higher in invasive ductal carcinomas (P = 0.0002) with protein expression predominantly in cellular membrane and lesser in cytoplasm. Western blot and RT-PCR analyses showed that the expression of Glut-1 protein and mRNA were significantly increased in invasive ductal carcinoma than fibroadenoma (P =0.001 for protein; P <0.05 for mRNA) and adenosis (P =0.001 for protein; P < 0.05 for mRNA). There was a significant difference among groups (P = 0.0002 for protein; P = 0.0001 for mRNA). CONCLUSIONS: Glucose transport activity, as indicated by Glut-1 protein and its mRNA expression, significantly increases in breast carcinoma than non-cancerous lesions. The over-expression of Glut-1 in breast carcinoma is tightly coupled with tumor cell proliferation, invasion and metastasis, implying that Glut-1 may serve as a new marker in the early diagnosis and prognostication of breast malignancy as well as a new therapeutic target.

Heat shock protein 70 fused to or complexed with hantavirus nucleocapsid protein significantly enhances specific humoral and cellular immune responses in C57BL/6 mice.

Heat shock proteins (HSPs) are known to act as an effective molecular adjuvant to enhance the induction of antigen peptide-specific cellular immunity, when coupled with the antigen or peptide. Hantaan virus (HTNV) nucleocapsid protein (NP) is relatively conserved among hantaviruses and highly immunogenic in both animals and humans. To analyze the influence of HSP70 on NP vaccine potency, and evaluate the possibility of developing a novel effective vaccine against hantaviruses, we constructed prokaryotic expression plasmids, and expressed three recombinant proteins, namely, HTNV NP, HSP70 and HSP70-NP fusion protein. As an alternative to fusion protein, we also generated HSP70 and HTNV NP complexes (HSP70+NP) in vitro. C57BL/6 mice were immunized with those recombinant proteins, the humoral and cellular responses elicited against NP were measured by ELISA, fluorescence flow cytometry, cytotoxicity assays, and IFN-gamma ELISPOT assay. We found that immunization of mice with HSP70-NP fusion protein, or HSP70+NP complexes elicited significantly higher NP-specific antibody titers, frequencies of IFN-gamma-producing cells and cytotoxic T lymphocyte (CTL) activities in vivo than conventional HTNV NP vaccination. Antibody isotype analysis showed that the antibody response was characterized by a higher HTNV NP-specific titer of IgG2a than IgG1 antibodies, resulting in a significant higher IgG2a/IgG1 ratio. By comparison, HSP70-NP fusion protein is significantly superior to HSP70+NP complexes in enhancement of NP antigenicity. These results indicated that HSP70, when fused to or complexed with HTNV NP, greatly enhance NP vaccine potency by preferential induction of a predominant Th1 immune response in a NP-specific, HSP70-dependent manner.

[Expression of Hsp70 Grp94 and IgG in human lung carcinoma].

AIM: To explore the expression and significance of heat shock protein 70 (Hsp70), glucose regulated protein 94 (Grp94) and immunoglobulin G (IgG) in human lung carcinoma. METHODS: The expression of Hsp70, Grp94 and IgG in 40 human lung carcinomas was studied using immunohistochemical technique and image analysis. The localization among Hsp70, Grp94 and IgG was analyzed by double labeling immunofluorescent staining and laser scanning confocal microscopy. RESULTS: Hsp70, Grp94 and IgG in Human lung carcinomas showed high expression. The positive rate of Hsp70, Grp94 and IgG was 65% (26/40), 45% (18/40), and 82.5% (33/40), respectively. The average value of optical density was 5.10 +/- 0.32, 3.52 +/- 0.35, and 8.12 +/- 0.31, respectively. Hsp70 was localized in nucleus and cellular cytoplasm while Grp94 and IgG were mainly localized in cellular cytoplasm. Ten cases showed Hsp70 was co-localized with IgG and Eighteen cases showed Grp94 was co-localized with IgG. CONCLUSION: High expression of Hsp70, Grp94 and IgG in Human lung carcinomas suggested that Hsp70, Grp94 and IgG might play an important role in the development of human lung carcinoma. IgG is co-localized with Hsp70 or Grp94. The study will lay a theorical basis for further research on anti-tumor immunotherapy.

HSP70 gene fused with Hantavirus S segment DNA significantly enhances the DNA vaccine potency against hantaviral nucleocapsid protein in vivo.

Heat shock proteins (HSPs) have been shown to act as adjuvants when coadministered with peptide antigens or given as fusion proteins and enhance the vaccination efficiency. To evaluate the enhancement of the potency of Hantaan virus (HTNV) nucleocapsid protein (NP) immunogenicity by heat shock protein 70 (HSP70), we developed a novel chimeric HTNV S-HSP70 DNA vaccine plasmid by genetically linking HSP70 gene to the full-length HTNV S segment DNA (HTNV S DNA). C57BL/6 mice were immunized with this plasmid followed by a subsequent boost with homologous recombinant protein. The levels of HTNV NP-specific antibody and cellular immune response were measured by use of ELISA, fluorescence activated cell sorter (FACS) analysis, cytotoxicity assay, and IFN-gamma ELISPOT assay. We found that HTNV S-HSP70 DNA vaccination significantly increased the levels of HTNV NP-specific antibody, IgG2a/IgG1 ratio, IFN-gamma producing CD8+ T-cell precursor frequencies, and cytotoxic T lymphocyte (CTL) response when compared with immunization with HTNV S DNA alone or HTNV S DNA physically mixed with HSP70 DNA. By contrast, HSP70 DNA or vector DNA immunization could not induce appreciable levels of specific antibodies and CTL response. Thus, we demonstrate for the first time that HSP70-based HTNV S DNA can induce both humoral and cellular immune response specific for HTNV NP and is a promising candidate DNA vaccine for HTNV infection.