Heparin inhibits plaque formation by cell-free Marek's disease viruses in vitro

The mechanisms of Marek's disease virus (MDV) entry to host cells have not yet been analyzed. Heparan sulfate (HS) on the cell surface serves as a receptor for several herpesviruses in mammalian species. In this study, we demonstrated that plaque formation by cell-free MDV is inhibited by the addition of soluble heparin to the cell culture. Moreover, pretreatment of susceptible cells, chicken embryo fibroblasts, with heparinase, partially reduced infectivity of the cell-free MDV. From these results, it was suggested that the MDV entry, at least in the case of cell-free MDV, is dependent on the presence of cell surface glycosaminoglycans, principally HS.

An investigation of heavy metal exposure and risks to wildlife in the Kafue flats of Zambia

Exposure and ecological risks to heavy metals (copper, zinc, manganese, iron) at Lochnivar and Blue Lagoon National Parks in wildlife dependent on the Kafue river contaminated with mining waste was evaluated. Samples included water, fish, grasses and Kafue Lechwe (Kobus leche kafuensis) liver. At both parks copper ranged from 0.03-0.04 mg/l; 3.0-6.0 mg/kg; 11.0-44.0 mg/kg; trace -199.0 mg/kg; while zinc was 0.01 mg/l; 32.0-82.0 mg/kg; 15.0-21.0 mg/kg; and 52.0-138.0 mg/kg; in water, fish, grasses and lechwe, respectively. Manganese ranges were 0.15-0.16 mg/l; 7.0-18.0 mg/kg; 51.0-145.0 mg/kg; and 40.0-53.0 mg/kg while iron ranges were 0.13-0.14 mg/l; 26.0-134.0 mg/kg; 1766.0-1797.0 mg/kg; and 131.0-856.0 mg/kg; in water, fish, grasses and lechwe, respectively. Levels in all samples except water were high indicating potential for adverse effects.

Lack of disease-specific amino acid changes in the viral proteins of JC virus isolates from the brain with progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy (PML) is a fatal demyelinating disease of the central nervous system caused by a ubiquitous human polyomavirus designated as JC virus (JCV). JCVs in the brain of PML patients (PML-type JCVs) contain various regulatory regions generated from the archetypal regulatory region during persistence in the patients. We determined the complete DNA sequences of 2 PML-type isolates and 5 archetype isolates. Amino acid sequences of individual viral proteins were deduced from complete DNA sequences, and were compared among 16 isolates (6 PML types and 10 archetypes). From the data obtained, we concluded that PML-associated amino acid changes did not occur in the viral proteins of PML-type JCVs.

Expression of fas (CD95) ligand is correlated with IL-10 and granulocyte colony-stimulating factor expression in oral and oropharyngeal squamous cell carcinoma

The Fas/Fas ligand (FasL) pathway has been shown to be an important cellular pathway mediating apoptosis. In this study we investigated the expression of Fas and FasL and the rate of spontaneous apoptosis in 58 oral and oropharyngeal squamous cell carcinoma (SCC) by using immunohistochemical techniques. There was no correlation between Fas or FasL expression and clinicopathological factors. The expression of Fas in the tumor did not affect spontaneous apoptosis of the tumor cells. However, FasL expression was associated with IL-10 and granulocyte colony-stimulating factor expression in oral and oropharyngeal SCC. These results suggested that the Fas/FasL system is connected with the expression of various factors including cytokines in tumor cells.

Issues in tick vaccine development: identification and characterization of potential candidate vaccine antigens

It is well established that acquired immunity against tick infestation can be induced by repeated tick infestation or by active immunization with either crude or purified native as well as recombinant antigens. This review provides insights into the development of tick vaccines with reference to identification, purification and molecular cloning of candidate target antigens.

Conventional tumor markers are prognostic indicators in patients with head and neck squamous cell carcinoma

We tested for squamous cell carcinoma-related antigen (SCC), carcinoembryonic antigen (CEA), ferritin, immunosuppressive acid protein (IAP) and sialic acid in the serum from 247 patients with head and neck squamous cell carcinoma prior to therapy. Significant correlations were found between IAP and tumor size, lymph node metastasis, and clinical stage (P<0.0001, P<0.001, and P<0.0001). Also, sialic acid and SCC were also correlated with tumor size, lymph node metastasis, and clinical stage. Moreover IAP, sialic acid and SCC were strongly associated with survival rate (P<0.0001, P = 0.0230 and P = 0.0159). A multivariate Cox proportional hazard model demonstrated that being positive for IAP was an independent predictor for patients with H&NSCC (P = 0.0115). The results indicate that IAP, sialic acid and SCC are useful as prognostic factors.

Seroprevalence of bovine immunodeficiency virus and bovine leukemia virus in draught animals in Cambodia

Since bovine immunodeficiency virus (BIV), known as bovine lentivirus, has been detected in dairy and beef cattle in various countries around the world, a prevalence study of antibodies to BIV and bovine leukemia virus (BLV) was conducted in draught animals in five provinces in Cambodia, where protozoan parasite infections were suspected in some animals. To clarify the status of draught animals including Haryana, Brahman, mixed-breed, local breed cattle and muscle water buffaloes, a total of 544 cattle and 42 buffaloes were tested, and 26.3 and 16.7%, respectively, were found positive for anti-BIV p26 antibodies determined by Western blotting. There were 5.3% positive for anti-BLV antibodies detected by immunodiffusion test among the cattle, but no reactors among buffaloes and no dual infection for both BIV and BLV was determined in this study. Peripheral blood mononuclear cells from BIV-seropositive cattle were found to have BIV-provirus DNA, as detected by polymerase chain reaction and subsequent Southern blot hybridization. This is the first evidence for the presence of BIV and BLV infections in draught animals in tropical countries such as Cambodia. This wide distribution of BIV suggests its association with problems in animal health as reported worldwide, and that a primary BIV infection can predispose death of affected animals by other aggressive pathogens or stresses.

Characterization of an 84 kDa protein inducing an immediate hypersensitivity reaction in rabbits sensitized to Haemaphysalis longicornis ticks

An immunogenic 84 kDa protein was isolated and purified from whole tick extracts of Haemaphysalis longicornis larvae by a combination of ion exchange, reverse phase and hydrophobic interaction chromatographies. The protein, when injected intradermally into rabbits exposed to repeated tick feeding, induces an immediate cutaneous hypersensitivity reaction. It has been purified to homogeneity as shown by sodium dodecyl sulphate polyacrylamide gel electrophoresis and silver staining. Amino acid sequences for two peptides derived from proteolytic cleavage of p84 were scanned against known proteins on the SWISS-PROT database. A 7 residue motif, ISGWGNT present in one of the two peptides appeared conserved in both vertebrate and invertebrate trypsin-like serine proteinases, while another 7 amino acid motif, HVPAGQI present in the second peptide showed homology to an Escherichia coli ATP-binding protein. We have discussed our findings in relation to isolation and characterization of target antigens for tick vaccine candidates.

Correlations between bone mineral density and circulating bone metabolic markers in diabetic patients

Diabetic osteopenia, a known chronic complication of diabetes, has been demonstrated with alterations in the calcium-vitamin D endocrine system. In order to investigate the relationship between the decrease of bone density and the altered mineral metabolism in non-insulin-dependent diabetes mellitus (NIDDM), 104 male clinical-proven NIDDM patients were studied. All patients were examined on metacarpal bone mineral density (m-BMD) by means of computed X-ray densitometry (CXD) methods. The values of the Z-score of m-BMD were significantly lower than those of age-matched controls (P<0.01). There was a positive correlation between m-BMD and serum calcium levels (P<0.01), but a negative correlation was conversely observed between m-BMD and serum intact parathyroid hormone (PTH) (P<0.01), indicating that the negative calcium balance under diabetic conditions could cause the decrease of m-BMD in NIDDM. Interestingly, since a significantly positive correlation was found between circulating levels of calcium and parathyroid hormone-related peptide (PTHrP) (P<0.05) but not PTH, it seems likely that PTHrP plays a more compensatory role on the maintenance of calcium homeostasis than PTH under diabetic conditions. Based on these observations, the CXD method would be useful in measuring the mineral density of cortical bone, and would also be beneficial to investigate underlying pathogenetic mechanism of diabetic osteopenia.

Theileria parva genomics reveals an atypical apicomplexan genome

The discipline of genomics is setting new paradigms in research approaches to resolving problems in human and animal health. We propose to determine the genome sequence of Theileria parva, a pathogen of cattle, using the random shotgun approach pioneered at The Institute for Genomic Research (TIGR). A number of features of the T. parva genome make it particularly suitable for this approach. The G+C content of genomic DNA is about 31%, non-coding repetitive DNA constitutes less than 1% of total DNA and a framework for the 10-12 Mbp genome is available in the form of a physical map for all four chromosomes. Minisatellite sequences are the only dispersed repetitive sequences identified so far, but they are limited in distribution to 13 of 33 SfiI fragments. Telomere and sub-telomeric non-coding sequences occupy less than 10 kbp at each chromosomal end and there are only two units encoding cytoplasmic rRNAs. Three sets of distinct multicopy sequences encoding ORFs have been identified but it is not known if these are associated with expression of parasite antigenic diversity. Protein coding genes exhibit a bias in codon usage and introns when present are unusually short. Like other apicomplexan organisms, T. parva contains two extrachromosomal DNAs, a mitochondrial DNA and a plastid DNA molecule. By annotating the genome sequence, in combination with the use of microarray technology and comparative genomics, we expect to gain significant insights into unique aspects of the biology of T. parva. We believe that the data will underpin future research to aid in the identification of targets of protective CD8+ cell mediated immune responses, and parasite molecules involved in inducing reversible host leukocyte transformation and tumour-like behaviour of transformed parasitised cells.

Difference in the meq gene between oncogenic and attenuated strains of Marek's disease virus serotype 1

Serotype 1 strains of Marek's disease virus (MDV1), except attenuated vaccine strains, are known to cause lymphomas in visceral organs of infected chickens. To know additional genetic differences between oncogenic and nononcogenic MDV1, polymerase chain reaction (PCR) was performed to amplify the meq gene of the viral genome. In addition to the 1,062-bp band including the native meq open reading frame (ORF), a 1.2-kb band was amplified from the DNA sample prepared from chick embryo fibroblast infected with an attenuated strain, CVI988, but not with oncogenic strains. Sequence analysis of the 1.2-kb band showed that a 178-bp sequence was inserted to the meq ORF of CVI988. This ORF could encode for the Meq protein with a different transactivator domain. Southern blot analysis also confirmed the insertion of the 178-bp sequence in the meq ORF of CVI988. This insertion of 178-bp sequence may explain the reason why CVI988 is not oncogenic.

Infection of bovine immunodeficiency virus and bovine leukemia virus in water buffalo and cattle populations in Pakistan

A survey of antibodies to bovine immunodeficiency virus (BIV) known as bovine lentivirus and bovine leukemia virus (BLV) was conducted with samples from water buffalo and cattle populations in Pakistan. A total of 370 water buffaloes and 76 cattle were tested, and 10.3% and 15.8%, respectively, were found positive for anti-BIV p26 antibodies determined by Western blotting, while 0.8% of water buffaloes and no cattle were positive for anti-BLV antibodies determined by immunodiffusion test. BIV-seropositive water buffaloes and cattle were found to have BIV proviral DNA in the peripheral blood mononuclear cells determined by nested polymerase chain reaction. This is the first report of BIV infections in water buffaloes.

Disruption of mdr1a p-glycoprotein gene results in dysfunction of blood-inner ear barrier in mice

P-glycoprotein (p-gp), a drug transporter in multidrug-resistant cancer cells, is a transmembrane protein encoded by mdr1a, mdr1b and mdr2 genes in mice. In our previous report, high level p-gp was immunohistochemically detected in capillary endothelial cells of the guinea pig inner ear, supporting a possible role as an extrusion pump in the blood-inner ear barrier (BIB). We investigated the functional involvement of p-gp in the inner ear using mdr1a gene knock-out mice [mdr1a(-/-) mice]. Pharmacokinetic analyses showed that mdr1a(-/-) mice displayed obviously increased accumulations of the p-gp-transported drugs doxorubicin (adriamycin, ADM) and vinblastine in the inner ear tissues compared with those in mdr1a(+/+) mice. Subsequent functional studies using auditory-evoked brainstem responses showed hearing impairment only in mdr1a(-/-) mice after administering these drugs. Furthermore, inhibition of p-gp function by co-administration of cyclosporin A (CsA) with doxorubicin (ADM) in mdr1a(+/+) mice resulted in increased accumulation of ADM in inner ear tissues and hearing impairment similar to that noted in mdr1a(-/-) mice. We conclude that mdr1a p-gp, which acts as an efflux pump in the inner ear, prevents ototoxicity induced by p-gp substrate drugs and contributes to a new functional mechanism in the BIB.

DNA from Mycobacterium bovis bacillus Calmette-Guérin (MY-1) inhibits immunoglobulin E production by human lymphocytes

A DNA fraction purified from Mycobacterium bovis bacillus Calmette-Guérin (BCG) and designated MY-1 induced interferon (IFN)-gamma production by human peripheral blood mononuclear cells (PBMC). IFN-gamma is well known as a downregulator of IgE production. In this study we investigated whether MY-1 regulates IgE production by human PBMC in vitro. MY-1 inhibited IgE production in PBMC taken from normal donors and stimulated with interleukin (IL)-4 plus monoclonal anti-CD40 antibody, without affecting production of IgA. MY-1 enhanced production of IFN-gamma and IL-12 by PBMC. Inhibition by MY-1 of IgE production was mediated by both IFN-gamma and IL-12, since the MY-1-induced suppression was blocked by the addition of monoclonal anti-IFN-gamma antibody, monoclonal anti-IL-12 antibody or a monoclonal antibody (mAb) directed at the IL-12 receptor. MY-1 inhibited the induction of epsilon germ-line transcript by IL-4. Additionally, MY-1 inhibited spontaneous in vitro production of IgE by PBMC from atopic donors in the absence of IL-4 plus anti-CD40 mAb. These results suggest that exposure to MY-1 may be a novel strategy for the treatment of IgE-related allergic disease.

A study of the systematics of Theileria spp. based upon small-subunit ribosomal RNA gene sequences

The systematics of benign and moderately pathogenic Theileria isolates from cattle and deer originating from different geographic regions was undertaken by small-subunit ribosomal RNA (SSU rRNA) gene nucleotide-sequence analysis. A maximum-likelihood phylogenetic tree constructed from these sequences resulted in two major divisions, each with a common ancestor. One major division branches into four relatively divergent groups, including (1) bovine Theileria sp. Type D (USA and Korea), (2) T. mutans Intona and Theileria sp. MSD (Africa), (3) T. cervi (USA), and (4) well-characterized pathogenic Theileria spp. (Africa). The other major division branches into two groups: (1) T. buffeli Warwick and T. buffeli Marula and (2) a second branch of closely related isolates with SSU rRNA gene Types B, B1, C, E, and H. Putative geographically associated diversity was noted only in the Korean bovine Theileria spp. with SSU rRNA gene types C and H and in African T. mutans Intona and Theileria sp. MSD. The current results show that the United States bovine Theileria isolates are not T. mutans because they have T. buffeli Marula (Type A) and/or Type D (species undesignated) SSU rRNA gene sequences. The taxonomic separation of T. buffeli Warwick from African T. mutans is confirmed in this study.

Anti-viral and anti-tumor effects induced by an attenuated Marek's disease virus in CD4- or CD8-deficient chickens

By vaccination with an attenuated Marek's disease virus (MDV), strain CVI988, chickens are protected from the development of T cell lymphoma caused by an oncogenic MDV. To clarify the role of T lymphocyte subsets in the protection mechanisms of this vaccine, vaccinated chickens were depleted of T cell subsets by neonatal thymectomy and injections of monoclonal antibodies specific to chicken CD4 and CD8 molecules, and then challenged with an oncogenic MDV, strain Md5. The MDV titers rescued from CD8(+) T cells, which are the main targets for latent infection and subsequent transformation by MDV, was much higher in the CD8-deficient vaccinated chickens than in untreated vaccinated chickens at the early stage of the latent phase. However, the neonatal vaccination prevented lymphoma formation by strain Md5 even in either CD4(+) or CD8(+) T cell-depleted chickens. These results suggest that specific CD8(+) T cell responses induced by the MD vaccine play a crucial role in the prevention of MDV infection during the latent phase, but may not be essential for the prevention of lymphoma formation by an oncogenic MDV.

Apoptosis-promoting gene (bax) transfer potentiates sensitivity of squamous cell carcinoma to cisplatin in vitro and in vivo

Modulation of apoptosis may potentiate the sensitivity of tumor cells to chemotherapeutic agents, thus improving the clinical outcome of cancer treatment. Bax, an apoptosis-promoting member of the bcl-2 family, may be a key factor influencing the chemosensitivity of tumor cells, however, its involvement in cellular sensitivity to anti-cancer drugs remains uncertain in squamous cell carcinoma (SCC). To investigate the role of bax gene expression in modulating cisplatin (CDDP)-induced apoptosis in vitro, an established CDDP-resistant human head and neck SCC (IMC-3 cell line) was transfected with bax gene-bearing mammalian expression vector. Overexpression of the bax gene in CDDP-resistant IMC-3 cells elevated the CDDP susceptibility of tumor cells to a level similar to that of the parental IMC-3 cells. In an in vivo study, percutaneous transfer of apoptosis-promoting bax gene by particle-mediated (gene gun) delivery caused overexpression of Bax in SCC, which was confirmed by immunohistochemical staining, and inhibited the growth of mouse CDDP-resistant SCC. Furthermore, combination therapy with bax gene transfer and subcutaneous administration of CDDP at 3-day intervals markedly inhibited the growth of mouse SCC. Thus, overexpression of bax in SCC by a gene gun system appears to be a rational approach to improving the efficacy of chemotherapy and treatment outcome. We suggest that exogenous bax expression may have therapeutic applications for enhancing chemotherapy in SCC.

JC virus genotypes in a Taiwan aboriginal tribe (Bunun): implications for its population history

The origin of Taiwanese aborigines remains obscure; it has been speculated that they may be from either mainland China or southeastern Asia. We used the JCV genotyping method to elucidate the origin of Bunun aborigines who now live in central mountain areas of Taiwan. We found that Bunun aborigines carried two major (B1-a2 and CY) and two minor JCV genotypes (B1-a1 and SC). This was contrasted with the JCV genotype profile in modern Taiwanese: one major (SC) and two minor genotypes (CY and B1-a1). It thus appears that B1-a2 and CY are indigenous to the Bunun tribe. B1-a2 was first identified in this study as a discrete cluster that contained only Bunun and Philippine JCV isolates and that was closely related to B1-a1, one of the three common JCV genotypes in China. CY predominates in North China, while SC predominates in South China and southeastern Asia. The present findings suggest that the Bunun tribe is an admixture of two ethnic groups, one carrying B1-a2 and the other carrying CY. In other words, it is likely that the Bunun tribe was established by two waves of immigrations from mainland Asia, predating those by southern Chinese which began in the 17th century.

Expression of p27 is associated with Bax expression and spontaneous apoptosis in oral and oropharyngeal carcinoma

p27Kip1, a cyclin-dependent kinase inhibitor, is a negative regulator of the cell cycle, and apoptosis is a genetically encoded program of cell death. To clarify the relationship between the cell cycle and apoptosis, we investigated expression of p27, cyclin D1 and apoptosis-related proteins (p53, Bax, Bcl-2 and c-Myc) in 60 cases of oral and oropharyngeal squamous-cell carcinoma (SCC) using an immuno-histochemical approach, and evaluated spontaneous apoptosis in vivo. Our most notable finding was that spontaneous apoptosis in the p27-positive group was significantly higher than that in the p27-negative group (p = 0.028). In addition, the percentage of p27-positive cells was clearly correlated with that of Bax-positive cells (gamma = 0.288, p = 0.028) and with that of cyclin D1-positive cells (gamma = 0.416, p = 0.002). Expression of p27 was inversely associated with the clinical stage of total tumor progression (p = 0.027). However, no correlation was found between p27 expression and the following parameters: gender, tumor size, lymph node metastasis, overall survival and disease-free survival. Our results give evidence that the action of the cell-cycle regulator p27 is closely linked with apoptosis in clinical samples from patients and indicate that over-expression of p27 might induce apoptosis in cancer cells through elevation of Bax expression, thereby acting on tumor progression.

Decreased expression of Bax is correlated with poor prognosis in oral and oropharyngeal carcinoma

We investigated the expression of apoptosis-related factors, p53, Bax, Bcl-2, and spontaneous apoptosis in 57 cases of oral and oropharyngeal squamous cell carcinoma (SCC) by immunochemical staining and ApopTag kit. Positive expression of Bax was inversely associated with advanced tumor stage (P = 0.0225), lymph node metastasis (P = 0.0225), clinical stage (P = 0.0083) and poor prognosis (P = 0.0478). Positive expression of p53 was related to poor prognosis (P = 0.0445) and was associated with negative expression of Bax (P = 0.0439). The apoptosis index did not correlate with clinical outcome. These results suggest that abnormality of Bax expression plays an important role in tumor progression in oral and oropharyngeal SCC.

Type-3 dengue viruses responsible for the dengue epidemic in Malaysia during 1993-1994

To characterize the dengue epidemic that recently occurred in Malaysia, we sequenced cDNAs from nine 1993-1994 dengue virus type-3 (DEN-3) isolates in Malaysia (DEN-3 was the most common type in Malaysia during this period). Nucleic acid sequences (720 nucleotides in length) from the nine isolates, encompassing the precursor of membrane protein (preM) and membrane (M) protein genes and part of the envelope (E) protein gene were aligned with various reference DEN-3 sequences to generate a neighbor-joining phylogenetic tree. According to the constructed tree, the nine Malaysian isolates were grouped into subtype II, which comprises Thai isolates from 1962 to 1987. Five earlier DEN-3 virus Malaysian isolates from 1974 to 1981 belonged to subtype I. The present data indicate that the recent dengue epidemic in Malaysia was due to the introduction of DEN-3 viruses previously endemic to Thailand.

Up-regulation of tumor necrosis factor alpha mRNA is associated with bovine-leukemia virus (BLV) elimination in the early phase of infection

Protective immune responses were analyzed in eight sheep vaccinated with BLV envelope peptides and experimentally infected with bovine-leukemia virus (BLV). Five of eight peptide-immunized sheep showed a high T-cell proliferative response to the BLV peptides and all of these were protected from the infection. The other three peptide-immunized sheep showed no T-cell proliferative responses to any BLV antigens similar to control sheep, though they also exhibited resistance to BLV challenge. To investigate other mechanisms which suppress BLV expansion in these non-responding sheep, we measured the levels of the cytokine expressions before, and after, BLV challenge using competitive reverse-transcriptase polymerase chain-reaction systems. It was revealed that the expression of tumor necrosis factor alpha (TNFalpha) was higher in BLV-resistant sheep than in BLV-susceptible sheep. Thus, TNFalpha expression rather than specific T-cell activity may play an important role in the protective mechanism against BLV infection, at least during the primary viremia phase.

Molecular cloning of two Haemaphysalis longicornis cathepsin L-like cysteine proteinase genes

Immunological protection of mammalian hosts against tick infestation has been proposed as the most sustainable alternative tick control method to the current use of acaricides which has several limitations. The success of this method is dependent on the identification of key molecules for use as tick vaccine antigens. Proteolytic enzymes are involved in a wide range of cellular processes in eukaryotes such as development regulation and nutrition, thus they can be considered as good target antigens for a tick vaccine. In the present study we used primers designed based on the consensus amino acid motifs flanking the conserved active sites C25 and N175 present in all papain-like cysteine proteinases to amplify by polymerase chain reaction, sequence and characterize two Haemaphysalis longicornis tick cysteine proteinase genes. Based on the nucleotide and deduced amino acid sequences, both genes were identified as members of the cysteine proteinase gene family by presence in their sequences of consensus motifs flanking the conserved active sites C25, H150 and N175 that are present in all papain-like cysteine proteinases. Both genes are about 1.2 kb in size and show high sequence homology predominantly to invertebrate cathepsin L-like cysteine proteinases.

CD40 stimulation inhibits cell growth and Fas-mediated apoptosis in a thyroid cancer cell line

CD40 plays a critical role in the humoral immune response, especially in B-cell proliferation, differentiation, production of antibody, secretion of cytokines, and apoptosis. Here, we examined CD40 expression on six head and neck cancer cell lines by flow cytometry. Only the HTC/C3 cell line, which originated from a thyroid cancer, expressed CD40 on the surface of the cells. Coculture with anti-CD40 mAb inhibited colony formation of HTC/C3 cells. CD40 stimulation enhanced Fas expression on HTC/C3 cells. Although HTC/C3 cells are sensitive to Fas-mediated apoptosis, CD40 stimulation inhibited Fas-mediated apoptosis in HTC/C3 cells. CD40 stimulation enhanced Bcl-2 expression, and antisense oligonucleotide against bcl-2 canceled the inhibition of HTC/C3 cell growth caused by CD40 stimulation. Additionally, more anti-CD40 mAb-treated HTC/C3 cells were accumulated in G1 phase, and fewer in S phase, compared to nontreated cells. These results suggest that CD40 stimulation might be involved in the slow growth rate of CD40-bearing cancer cells, and they suggest a new biological approach to the treatment of cancers.

Characterization of immune responses caused by bovine leukemia virus envelope peptides in sheep

To study the immunomodulative activity caused by bovine leukemia virus envelope (BLV Env) peptide, sheep were immunized with two kinds of Th-epitope peptides, peptide 98 (BLV Env 98-117), and 61 (BLV Env 61-78). Four of eight immunized sheep showed specific proliferative responses against both of the peptide stimulations. To characterize the cells responding to the peptides, peptide-specific cells were established from the responding sheep by the continuous stimulation of peripheral blood mononuclear cells (PBMCs) with either peptide 98 or 61 in vitro. The peptide 98-specific cells consisted of CD4-positive cells, whereas the peptide 61-specific cells consisted of CD8-positive cells and MHC class II-positive cells. In addition, cytokine profile analysis indicated that the peptide 98-stimulated cells expressed IFN-gamma but not IL-10, although the peptide 61-stimulated cells expressed IL-10 but not IFN-gamma. These results show that BLV envelope peptides 98 and 61 can modulate immune responses of sheep lymphocytes in different ways and may contribute to the pathogenesis of BLV infection.