Encephalitis induced by bovine herpesvirus 5 and protection by prior vaccination or infection with bovine herpesvirus 1.
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Calves were intranasally challenged with bovine herpesvirus 5 (BHV5) and followed for the development of viral infection, clinical encephalitis, histologic lesions in the brain, and viral sequences in the trigeminal ganglia. Calves that were previously vaccinated with bovine herepesvirus 1 (BHV1, n = 4) or previously infected with BHV1 (n = 5) or that had not been exposed to either virus (n = 4) were compared. No calf developed signs of encephalitis, although all calves developed an infection as indicated by nasal secretion of BHV5 and seroconversion to the virus. Histologic lesions of encephalitis consisting of multifocal gliosis and perivascular cuffs of lymphocytes were observed in calves not previously exposed to BHV1. BHV5 sequences were amplified from the trigeminal ganglia of calves previously vaccinated and from calves not previously exposed to BHV1; calves sequentially challenged with BHV1 and later BHV5 had exclusively BHV1 sequences in their trigeminal ganglia. Administration of dexamethasone 28 days after BHV5 challenge did not influence clinical disease or histologic lesions in either previously unexposed calves (n = 2) or previously immunized calves (n = 2), although it did cause recrudescence of BHV5, as detected by nasal virus secretion. (+info)
Activation of caspases and p53 by bovine herpesvirus 1 infection results in programmed cell death and efficient virus release.
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Programmed cell death (PCD), or apoptosis, is initiated in response to various stimuli, including virus infection. Bovine herpesvirus 1 (BHV-1) induces PCD in peripheral blood mononuclear cells at the G0/G1 phase of the cell cycle (E. Hanon, S. Hoornaert, F. Dequiedt, A. Vanderplasschen, J. Lyaku, L. Willems, and P.-P. Pastoret, Virology 232:351-358, 1997). However, penetration of virus particles is not required for PCD (E. Hanon, G. Meyer, A. Vanderplasschen, C. Dessy-Doize, E. Thiry, and P. P. Pastoret, J. Virol. 72:7638-7641, 1998). The mechanism by which BHV-1 induces PCD in peripheral blood mononuclear cells is not understood, nor is it clear whether nonlymphoid cells undergo PCD following infection. This study demonstrates that infection of bovine kidney (MDBK) cells with BHV-1 leads to PCD, as judged by terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling, DNA laddering, and chromatin condensation. p53 appears to be important in this process, because p53 levels and promoter activity increased after infection. Expression of proteins that are stimulated by p53 (p21(Waf1) and Bax) is also activated after infection. Cleavage of Bcl-xL, a protein that inhibits PCD, occurred after infection, suggesting that caspases (interleukin-1beta-converting enzyme-like proteases) were activated. Other caspase substrates [poly(ADP-ribose) polymerase and actin] are also cleaved during the late stages of infection. Inhibition of caspase activity delayed cytotoxic activity and virus release but increased the overall virus yield. Taken together, these results indicate that nonlymphoid cells undergo PCD near the end of productive infection and further suggest that caspases enhance virus release. (+info)
Bovine herpesvirus 1-induced apoptotic cell death: role of glycoprotein D.
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Bovine herpesvirus 1 (BHV-1) induces apoptotic cell death in peripheral blood mononuclear cells and in bovine B lymphoma (BL-3) cells. Attachment but not penetration of BHV-1 is necessary to induce apoptosis in target cells, suggesting that one or more BHV-1 envelope glycoproteins could be involved in the activation of the apoptotic process. In the present study, we demonstrate that, although BHV-1 virions devoid of glycoprotein D (BHV-1 gD-/-) still bind to BL-3 cells, they are no longer able to induce apoptosis. In contrast, virions that contain glycoprotein D (gD) in the viral envelope but do not genetically encode gD (BHV-1 gD-/+) induce a level of apoptosis comparable to that produced by wild-type (wt) BHV-1. In addition, monoclonal antibodies directed against gD, but not against gB or gC, strongly reduced the high levels of apoptosis induced by BHV-1. These observations demonstrate that the induction of apoptosis is directly due to BHV-1 viral particles harboring gD in the viral envelope. Interestingly, binding of affinity-purified gD to BL-3 cells did not induce apoptosis but inhibited the ability of wt BHV-1 to induce apoptosis. Altogether, these results provide evidence for the direct or indirect involvement of gD in the mechanism by which BHV-1 induces apoptosis. (+info)
Susceptibility of bovine antigen-presenting cells to infection by bovine herpesvirus 1 and in vitro presentation to T cells: two independent events.
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The aim of the present study was to develop an in vitro system for presentation of bovine herpesvirus 1 (BHV-1) antigens to bovine T lymphocytes and to characterize the antigen-presenting cells (APC) which efficiently activate CD4(+) T cells. Two approaches were used to monitor the infection of APC by BHV-1 as follows: (i) detection of viral glycoproteins at the cell surface by immunofluorescence staining and (ii) detection of UL26 transcripts by reverse transcription-PCR. The monocytes were infected, while dendritic cells (DC) did not demonstrate any detectable viral expression. These data suggest that monocytes are one site of replication, while DC are not. The capacities of monocytes and DC to present BHV-1 viral antigens in vitro were compared. T lymphocytes (CD2(+) or CD4(+)) from BHV-1 immune cattle were stimulated in the presence of APC previously incubated with live or inactivated wild-type BHV-1. DC stimulated strong proliferation of Ag-specific T cells, while monocytes were poor stimulators of T-cell proliferation. When viral attachment to the surface of the APC was inhibited by virus pretreatment with soluble heparin, T-cell proliferation was dramatically decreased. Unexpectedly, incubation of DC and monocytes with the deletion mutant BHV-1 gD-/-, which displays impaired fusion capacity, resulted in strong activation of T lymphocytes by both APC types. Collectively, these results indicate that presentation of BHV-1 antigens to immune T cells is effective in the absence of productive infection and suggest that BHV-1 gD-/- mutant virus could be used to induce virus-specific immune responses in cattle. (+info)
Bovine herpes virus expressing envelope protein (E2) of bovine viral diarrhea virus as a vaccine candidate.
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The gene encoding the envelope protein (E2) of bovine viral diarrhea virus (BVDV) was expressed under the thymidine kinase (TK) promoter of Korean bovine herpesvirus 1 (BHV-1) isolate. Thymidine kinase negative (TK-) BHV-1 recombinants expressing E2 of BVDV were constructed and the expression of E2 was identified by immunofluorescence and Western blotting. Compared to wild type BHV-1, the recombinant BHV-1 had a delayed cytopathogenic effect in cells. The immunogenicity of the recombinant BHV-1 was examined in guinea pigs and cattle. Although an increase in body temperature was detected for a few days, the inoculated cattle returned to normal temperature with the development of neutralizing antibodies to BVDV. (+info)
Mucosal immunization of calves with recombinant bovine adenovirus-3: induction of protective immunity to bovine herpesvirus-1.
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To determine the potential of replication-competent (E3-deleted) bovine adenovirus-3 (BAV-3) as a delivery system for vaccine antigens in calves, we evaluated the ability of recombinant BAV-3 expressing different forms of of bovine herpesvirus-1 (BHV-1) glycoprotein gD to protect against BHV-1 infection in calves that had pre-existing BAV-3 specific antibodies. Three- to four-month-old calves, vaccinated intranasally with recombinant BAV-3 expressing full-length gD (BAV3.E3gD) or a truncated version of gD (gDt) (BAV3.E3gDt), or with E3-deleted BAV-3 (BAV3.E3d; control), were challenged with BHV-1 strain 108. Vaccination with BAV3.E3gD or BAV3.E3gDt induced gD-specific antibody responses in serum and nasal secretions, and primed calves for gD-specific lymphoproliferative responses. In addition, all calves developed complement-independent neutralizing antibodies against BHV-1. Protection against viral challenge was observed in calves vaccinated with recombinant BAV3.E3gD or BAV3.E3gDt as shown by a significant reduction in body temperature and clinical disease, and a partial reduction in the amount and duration of virus excretion in nasal secretions. These results indicate that replication-competent BAV-3-based vectors can induce protective immune responses in calves (the natural host) that have pre-existing BAV-3-specific antibodies. (+info)
Epitopes on glycoprotein C of bovine herpesvirus-1 (BHV-1) that allow differentiation between BHV-1.1 and BHV-1.2 strains.
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In cattle, bovine herpesvirus-1 (BHV-1) can cause a mild genital disease known as infectious pustular vulvovaginitis (IPV) and a more severe respiratory disease known as infectious bovine rhinotracheitis (IBR). On the basis of epidemiological data, it has been proposed that these diseases are caused by strains with different genotypes (IBR by BHV-1.1 and IPV by BHV-1.2 strains). By using a panel of 237 BHV-1 isolates, a monoclonal antibody (MAb 71) was found that failed to react with all 54 putative IPV strains in the panel, and another MAb (77) was found that did not react with 16 of these 54 IPV strains. Because MAbs 71 and 77 also failed to react with a BHV-1.1 glycoprotein C (gC)-deletion mutant, it was hypothesized that both MAbs recognize BHV-1.1 gC. By marker-rescue experiments and by expressing fragments of the BHV-1.1 gC gene in recombinant baculoviruses, it was shown that both MAbs indeed recognize BHV-1.1 gC. MAb 71 recognizes the N-terminal half and MAb 77 recognizes the C-terminal half of BHV-1.1 gC. In a PEPSCAN analysis with 12-mer oligopeptides, MAb 71 reacted with overlapping peptides containing gC amino acid residues 75-80 and MAb 77 did not react in this analysis. The differences in gC found in this study may contribute to the biological differences between BHV-1.1 and BHV-1.2. (+info)
Characterization of promoters integrated in the genome of bovine herpesvirus-1 (BHV-1).
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Bovine herpesvirus-1 (BHV-1) has been used as a vector of live recombinant vaccines for cattle which express the genes of other pathogens. Because of the importance of the choice of the promoter which allows the efficient expression of the foreign genes in the BHV-1 vector, we compared the relative efficacy of various promoters integrated in the BHV-1 genome. The promoter sequences of the BHV-1 thymidine kinase (tk), gB, gC, SV40 early, and pseudorabies virus (PRV) immediate early (IE) genes were placed at the upstream of the open reading frame of the chloramphenycol acetyl transferase (CAT) gene and the promoter-CAT sequences were integrated into the tk gene of BHV-1 by homologous recombination. The promoter activity was assayed by measuring the CAT activity in the extracts of Madin Darby bovine kidney (MDBK) cells infected with the recombinant BHV-1. The PRV IE promoter was activated earlier and maintained at a higher level activity than the BHV-1 gB or gC promoters throughout the most of the growth phase of BHV-1. At the late phase, however, the activities of the BHV-1 gB and gC promoters reached the higher level. The BHV-1 tk promoter activity was low and the SV40 early promoter was hardly activated when integrated into the BHV-1 genome. promoter, recombinant BHV-1. (+info)