scholarly journals Caspase 9 Is Essential for Herpes Simplex Virus Type 2-Induced Apoptosis in T Cells

2010 ◽  
Vol 84 (6) ◽  
pp. 3116-3120 ◽  
Author(s):  
Michael J. Vanden Oever ◽  
Jin-Young Han

ABSTRACT Herpes simplex virus type 2 (HSV-2) induces apoptosis in T cells by a caspase-dependent mechanism. Apoptosis can occur via extrinsic (death receptor) and/or intrinsic (mitochondrial) pathways. Here, we show that the initiator caspase for the intrinsic pathway is activated in T cells following HSV-2 exposure. To determine the respective contributions of intrinsic and extrinsic pathways, we assessed apoptosis in Jurkat cells that are deficient in caspase 8 or Fas-associating protein with death domain (FADD) for the extrinsic pathway and in cells deficient in caspase 9 for the intrinsic pathway. Our results indicate HSV-2-induced apoptosis in T cells occurs via the intrinsic pathway.

2003 ◽  
Vol 77 (11) ◽  
pp. 6556-6561 ◽  
Author(s):  
Ling Jin ◽  
Weiping Peng ◽  
Guey-Chuen Perng ◽  
David J. Brick ◽  
Anthony B. Nesburn ◽  
...  

ABSTRACT The herpes simplex virus type 1 (HSV-1) latency-associated transcript (LAT) gene is essential for the high spontaneous and induced reactivation phenotype of HSV-1 in the rabbit ocular model and for the high induced reactivation phenotype in the mouse ocular model. Recently we showed that LAT has an antiapoptosis function, and we hypothesized that LAT's ability to inhibit apoptosis played an important role in LAT's ability to enhance the reactivation phenotype. Expression of just the first 1.5 kb of the 8.3-kb LAT gene is sufficient for both inhibition of apoptosis in an in vitro transient-transfection assay and the high spontaneous reactivation phenotype in vivo. Here we show the results of more complex mapping studies in which inhibition of apoptosis and the enhanced spontaneous reactivation phenotype also appear to be linked. The HSV-1 mutant virus dLAT371 has a high spontaneous reactivation phenotype in rabbits, suggesting that the LAT region deleted in this mutant (LAT nucleotides 76 to 447) is not required for this phenotype. The LAT3.3A viral mutant (which expresses LAT nucleotides 1 to 1499) also has a high spontaneous reactivation phenotype, suggesting that the region of LAT not expressed by this mutant (LAT nucleotide 1500 to the end of LAT) is also not required for this phenotype. Surprisingly, LAT2.9A, which is a combination of dLAT371 and LAT3.3A (i.e., it expresses LAT nucleotides 1 to 76 and 447 to 1499), has a low spontaneous reactivation phenotype indistinguishable from that of LAT null mutants. We report here that consistent with the low spontaneous reactivation phenotype of LAT2.9A, a plasmid expressing the identical LAT RNA did not inhibit caspase 9-induced apoptosis. In contrast, plasmids containing the same deletion but able to transcribe up to or past LAT nucleotide 2850 (rather than just up to LAT nucleotide 1499) inhibited caspase 9-induced apoptosis, consistent with the high spontaneous reactivation phenotype of dLAT371. Thus, LAT2.9A may have a low spontaneous reactivation phenotype because the LAT RNA that is made cannot block apoptosis, and dLAT371 apparently has a high spontaneous reactivation phenotype because the LAT RNA made has significant antiapoptosis activity. Furthermore, LAT appeared to have at least two regions capable of interfering with caspase 9-induced apoptosis. One region partially overlaps LAT nucleotides 76 to 447. The second region is partially (or completely) downstream of LAT nucleotide 1499.


2006 ◽  
Vol 80 (11) ◽  
pp. 5509-5515 ◽  
Author(s):  
Nancy Hosken ◽  
Patrick McGowan ◽  
Amalia Meier ◽  
David M. Koelle ◽  
Paul Sleath ◽  
...  

ABSTRACT Cytolytic T cells play a major role in controlling herpes simplex virus type 2 (HSV-2) infections in humans. In an effort to more thoroughly evaluate the response to HSV-2 directly, ex vivo, we developed an enzyme-linked immunospot (ELISPOT) assay that utilized pools of overlapping synthetic peptides presented by autologous dendritic cells to purified CD8+ T cells. Donor response rates to individual open reading frames (ORFs) ranged from fewer than 5% responding to as many as 70% responding, with the greatest frequency of responses (by ORF) being directed against UL39, UL25, UL27, ICP0, UL46, and UL47 in descending order of frequency. HSV-2-seropositive subjects responded to as few as 3 or as many as 46 of the 48 ORFs tested, with a median of 11 ORFs recognized. HLA-B*07 expression correlated with stronger responses overall that were directed primarily against UL49 and UL46. Cumulative precursor frequencies in the blood ranged from 500 to almost 6,000 HSV-2 spot-forming units/106 CD8+ T cells. The magnitude and breadth of the response in the infected population were greater than previously appreciated. Whether this variability in the CD8+ T-cell response within individuals is associated with the frequency of viral reactivation warrants further study.


2001 ◽  
Vol 82 (4) ◽  
pp. 845-853 ◽  
Author(s):  
Ali M. Harandi ◽  
Bo Svennerholm ◽  
Jan Holmgren ◽  
Kristina Eriksson

The role of B, CD4+ T and CD8+ T cells in both primary genital infection with attenuated herpes simplex virus type 2 (HSV-2) and development of protective immunity to a later challenge with virulent HSV-2 using lymphocyte-deficient mice has been elucidated. Following primary inoculation with attenuated thymidine kinase-deficient (TK−) HSV-2, B cell-deficient (μMT) mice developed a local viraemia and transient genital inflammation, suggesting a role for B cells in the innate control of local infection and inflammation. Natural antibodies are implicated in this process, as passive transfer of normal serum into μMT mice significantly reduced HSV-2 TK− shedding in the vaginal lumen, although it did not affect subsequent inflammation. Protection against lethal HSV-2 challenge was noted in HSV-2-vaccinated wild-type, CD8+ T cell-deficient and μMT mice and was characterized by strong virus-specific IFN-γ responses in vitro and delayed type hypersensitivity (DTH) responses in vivo. In contrast, CD4+ T cell-deficient (CD4−/−) mice had impaired HSV-2-specific IFN-γ production and DTH responses and succumbed rapidly to genital HSV-2 challenge. However, protective responses to HSV-2 could be induced in HSV-2-vaccinated CD4−/− mice by treatment with recombinant IFN-γ. Taken together, these results suggest that CD4+ T cells secreting IFN-γ are critical for immune protection against lethal genital HSV-2 re-infection, whereas B cells/natural antibodies have anti-viral and -inflammatory effects in the innate control of a primary infection.


1999 ◽  
Vol 73 (8) ◽  
pp. 6380-6386 ◽  
Author(s):  
Gregg N. Milligan

ABSTRACT Large numbers of polymorphonuclear leukocytes (PMNs) infiltrated the murine vaginal mucosa within 24 h after intravaginal inoculation with an attenuated strain of herpes simplex virus type 2 (HSV-2). The role of these cells in resolution of a primary genital infection and in protection of HSV-immune animals against challenge with a fully virulent HSV-2 strain was investigated. Depletion of greater than 95% of the PMNs at the vaginal mucosal surface prior to intravaginal inoculation with an attenuated HSV-2 strain resulted in significantly higher virus titers on days 3 to 7 but only slightly delayed resolution of the primary genital infection. These results suggest that neutrophils helped control the infection but that other immune mechanisms ultimately cleared the virus. Interestingly, depletion of PMNs from HSV-immune mice prior to challenge with a fully virulent HSV-2 strain resulted in a rise in virus titers to levels comparable to those of nonimmune mice and a more pronounced diminution of virus clearance from the vaginal mucosa despite the presence of HSV-specific B and T cells. Levels of gamma interferon (IFN-γ) and HSV-specific antibody were comparable in neutrophil-depleted and control-treated immune mice following HSV-2 challenge, suggesting that RB6-8C5 treatment did not impair T- and B-cell function. Therefore, these results suggest that neutrophils play a role in limiting and clearing HSV-2 vaginal infections and that they are, in association with HSV-specific B and T cells, an important component in immune protection of the vaginal mucosa.


2009 ◽  
Vol 83 (22) ◽  
pp. 11777-11783 ◽  
Author(s):  
Takahiro Ishikawa ◽  
Hisakata Yamada ◽  
Akiko Oyamada ◽  
Fumi Goshima ◽  
Yukihiro Nishiyama ◽  
...  

ABSTRACT Herpes simplex virus type 2 (HSV-2) induces acute local infection followed by latent infection in the nervous system and often leads to the development of lethal encephalitis in immunocompromised hosts. The mechanisms of immune protection against lethal HSV-2 infection, however, have not been clarified. In this study, we examined the roles of Fas-Fas ligand (FasL) signaling in lethal infection with HSV-2 by using mice with mutated Fas (lpr) or FasL (gld) in C57BL/6 background. Both lpr and gld mice exhibited higher mortality than wild-type (WT) C57BL/6 mice after infection with virulent HSV-2 strain 186 and showed significantly increased viral titers in the spinal cord compared with WT mice 9 days after infection, just before the mice started to die. There were no differences in the numbers of CD4+ and CD8+ T cells infiltrated in the spinal cord or in the levels of HSV-2-specific gamma interferon produced by those cells in a comparison of lpr and WT mice 9 days after infection. Adoptive transfer studies demonstrated that CD4+ T cells from WT mice protected gld mice from lethal infection by HSV-2. Furthermore, CD4+ T cells infiltrated in the spinal cord of HSV-2-infected WT mice expressed functional FasL that induced apoptosis of Fas-expressing target cells in vitro. These results suggest that FasL-mediated cytotoxic activity of CD4+ T cells plays an important role in host defense against lethal infection with HSV-2.


2005 ◽  
Vol 79 (23) ◽  
pp. 14546-14554 ◽  
Author(s):  
Melanie E. Dobbs ◽  
Jane E. Strasser ◽  
Chin-Fun Chu ◽  
Claudia Chalk ◽  
Gregg N. Milligan

ABSTRACT The T-cell-mediated resolution of herpes simplex virus type 2 (HSV-2) genital infections is not fully understood. In these studies, the mechanisms by which CD8+ T cells clear virus from the genital epithelium were examined. Ovalbumin (OVA)-specific CD8+ T cells from OT-I transgenic mice cleared a thymidine kinase-deficient, ovalbumin-expressing HSV-2 virus (HSV-2 tk− OVA) from the genital epithelium of recipient mice, and clearance was abrogated by in vivo neutralization of gamma interferon (IFN-γ). Further, CD8+ OT-I T cells deficient in IFN-γ were unable to clear HSV-2 tk− OVA from the vaginal epithelium. The requirement for cytolytic mechanisms in HSV-2 tk− OVA clearance was tested in radiation chimeras by adoptive transfer of wild-type or perforin-deficient OT-I T cells to irradiated Fas-defective or wild-type recipients. Although a dramatic decrease in viral load was observed early after challenge with HSV-2 tk− OVA, full resolution of the infection was not achieved in recipients lacking both perforin- and Fas-mediated cytolytic pathways. These results suggest that IFN-γ was responsible for an early rapid decrease in HSV-2 virus titer. However, either perforin- or Fas-mediated cytolytic mechanisms were required to achieve complete clearance of HSV-2 from the genital epithelium.


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