Multiple Defects, Including Premature Apoptosis, Prevent Kaposi's Sarcoma-Associated Herpesvirus Replication in Murine Cells

Austgen, Kathryn; Oakes, Scott A.; Ganem, Don

doi:10.1128/jvi.06600-11

Cited by 25 publications

(21 citation statements)

References 25 publications

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“…This observation of infected murine cells is consistent with a previous study, which has shown that KSHV can infect the mouse cells but that the infected cell numbers were low (8). However, it is unlikely that mouse cells can support a sustainable KSHV infection because it was shown by Austgen et al (18) that there are multiple postentry blocks to KSHV lytic replication in murine cells, and infected murine cells were associated with apoptotic cell death.…”

Section: Discussionsupporting

confidence: 90%

Humanized-BLT mouse model of Kaposi’s sarcoma-associated herpesvirus infection

Wang

Kang

Kumar

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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Lack of an effective small-animal model to study the Kaposi's sarcoma-associated herpesvirus (KSHV) infection in vivo has hampered studies on the pathogenesis and transmission of KSHV. The objective of our study was to determine whether the humanized BLT (bone marrow, liver, and thymus) mouse (hu-BLT) model generated from NOD/SCID/IL2rγ mice can be a useful model for studying KSHV infection. We have tested KSHV infection of hu-BLT mice via various routes of infection, including oral and intravaginal routes, to mimic natural routes of transmission, with recombinant KSHV over a 1-or 3-mo period. Infection was determined by measuring viral DNA, latent and lytic viral transcripts and antigens in various tissues by PCR, in situ hybridization, and immunohistochemical staining. KSHV DNA, as well as both latent and lytic viral transcripts and proteins, were detected in various tissues, via various routes of infection. Using double-labeled immune-fluorescence confocal microscopy, we found that KSHV can establish infection in human B cells and macrophages. Our results demonstrate that KSHV can establish a robust infection in the hu-BLT mice, via different routes of infection, including the oral mucosa which is the most common natural route of infection. This hu-BLT mouse not only will be a useful model for studying the pathogenesis of KSHV in vivo but can potentially be used to study the routes and spread of viral infection in the infected host. T he Kaposi's sarcoma (KS)-associated herpesvirus (KSHV), also known as the human herpesvirus 8, was first identified from KS tissues in 1994 (1). It is the etiologic agent for KS and is also associated with primary effusion lymphoma (PEL) and multicentric Castleman's disease (2). More recently it was also found to be associated with KSHV-associated inflammatory cytokine syndrome (3). Although substantial progress has been made in characterizing the virus, there are still many unanswered questions such as how KSHV infection can lead to disease manifestation and whether latent or lytic induction of KSHV are associated with malignancies. One of the reasons is a lack of a good small-animal model to study KSHV infection in vivo, which has hampered studies on how KSHV infects, spreads, and how it interacts with the host and ultimately leads to disease pathogenesis. Moreover, currently there is no vaccine against KSHV infection, and there is need for an effective animal model to evaluate the efficacy of vaccines if they are developed and for the testing of antiviral regimens.An ideal model should have relatively short generation time, reproduce rapidly, be inexpensive to maintain and house, and be easy to manipulate. An example is a rodent model that can be infected by KSHV effectively. Several small-rodent models have been tested for KSHV infection. The models include transplantation with both human KSHV-infected B lymphoma cells and primary human peripheral blood mononuclear cells in the SCID mouse (4), injection of KSHV into the human skin engrafted or the transplant of the SCID mice...

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Section: Discussionsupporting

confidence: 90%

Humanized-BLT mouse model of Kaposi’s sarcoma-associated herpesvirus infection

Wang

Kang

Kumar

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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“…10,60 In fact, KSHV DNA replication has been shown to be abrogated by the onset of premature apoptosis. 61 Hence, it is plausible that KSHV anti-apoptotic proteins ORF22, ORF25 and ORF64 may protect the cells from apoptotic stimuli prevailing in the lytic phase, thereby allowing the efficient production of virus particles. 62,63 In addition, apoptosis is an important defense mechanism of the host cell in the response to the de novo viral infection.…”

Section: Discussionmentioning

confidence: 99%

Structural proteins of Kaposi’s sarcoma-associated herpesvirus antagonize p53-mediated apoptosis

et al. 2014

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The tumor suppressor p53 is a central regulatory molecule of apoptosis and is commonly mutated in tumors. Kaposi's sarcoma-associated herpesvirus (KSHV)-related malignancies express wild-type p53. Accordingly, KSHV encodes proteins that counteract the cell death-inducing effects of p53. Here, the effects of all KSHV genes on the p53 signaling pathway were systematically analyzed using the reversely transfected cell microarray technology. With this approach we detected eight KSHV-encoded genes with potent p53 inhibiting activity in addition to the previously described inhibitory effects of KSHV genes ORF50, K10 and K10.5. Interestingly, the three most potent newly identified inhibitors were KSHV structural proteins, namely ORF22 (glycoprotein H), ORF25 (major capsid protein) and ORF64 (tegument protein). Validation of these results with a classical transfection approach showed that these proteins inhibited p53 signaling in a dose-dependent manner and that this effect could be reversed by small interfering RNA-mediated knockdown of the respective viral gene. All three genes inhibited p53-mediated apoptosis in response to Nutlin-3 treatment in non-infected and KSHV-infected cells. Addressing putative mechanisms, we could show that these proteins could also inhibit the transactivation of the promoters of apoptotic mediators of p53 such as BAX and PIG3. Altogether, we demonstrate for the first time that structural proteins of KSHV can counteract p53-induced apoptosis. These proteins are expressed in the late lytic phase of the viral life cycle and are incorporated into the KSHV virion. Accordingly, these genes may inhibit cell death in the productive and in the early entrance phase of KSHV infection.

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“…However, KSHV does not have a murine viral analogue and the human KSHV cannot productively replicate in mice [58]. Therefore, we adopted the iSLK-KSHV/DOX inducible in-vitro cell based system that is the closest available system to imitate a lytic and latent viral replication environment.…”

Section: Discussionmentioning

confidence: 99%

The Viral KSHV Chemokine vMIP-II Inhibits the Migration of Naive and Activated Human NK Cells by Antagonizing Two Distinct Chemokine Receptors

et al. 2013

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Natural killer (NK) cells are innate immune cells able to rapidly kill virus-infected and tumor cells. Two NK cell populations are found in the blood; the majority (90%) expresses the CD16 receptor and also express the CD56 protein in intermediate levels (CD56Dim CD16Pos) while the remaining 10% are CD16 negative and express CD56 in high levels (CD56Bright CD16Neg). NK cells also reside in some tissues and traffic to various infected organs through the usage of different chemokines and chemokine receptors. Kaposi's sarcoma-associated herpesvirus (KSHV) is a human virus that has developed numerous sophisticated and versatile strategies to escape the attack of immune cells such as NK cells. Here, we investigate whether the KSHV derived cytokine (vIL-6) and chemokines (vMIP-I, vMIP-II, vMIP-III) affect NK cell activity. Using transwell migration assays, KSHV infected cells, as well as fusion and recombinant proteins, we show that out of the four cytokine/chemokines encoded by KSHV, vMIP-II is the only one that binds to the majority of NK cells, affecting their migration. We demonstrate that vMIP-II binds to two different receptors, CX3CR1 and CCR5, expressed by naïve CD56Dim CD16Pos NK cells and activated NK cells, respectively. Furthermore, we show that the binding of vMIP-II to CX3CR1 and CCR5 blocks the binding of the natural ligands of these receptors, Fractalkine (Fck) and RANTES, respectively. Finally, we show that vMIP-II inhibits the migration of naïve and activated NK cells towards Fck and RANTES. Thus, we present here a novel mechanism in which KSHV uses a unique protein that antagonizes the activity of two distinct chemokine receptors to inhibit the migration of naïve and activated NK cells.

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Multiple Defects, Including Premature Apoptosis, Prevent Kaposi's Sarcoma-Associated Herpesvirus Replication in Murine Cells

Cited by 25 publications

References 25 publications

Humanized-BLT mouse model of Kaposi’s sarcoma-associated herpesvirus infection

Humanized-BLT mouse model of Kaposi’s sarcoma-associated herpesvirus infection

Structural proteins of Kaposi’s sarcoma-associated herpesvirus antagonize p53-mediated apoptosis

The Viral KSHV Chemokine vMIP-II Inhibits the Migration of Naive and Activated Human NK Cells by Antagonizing Two Distinct Chemokine Receptors

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