Mousepox in the C57BL/6 strain provides an improved model for evaluating anti-poxvirus therapies

Autophagy is a self-degradation process of cellular components. It plays both antiviral and pro-viral roles in the life cycle of different viruses and the pathogenesis of different viral diseases. In this study, we evaluated autophagy induction in splenocytes of ectromelia virus (ECTV)-resistant C57BL/6 and ECTV-susceptible BALB/c mice during infection with the Moscow strain of the ectromelia virus (ECTV-MOS). Autophagy was analyzed using the Western blot method by assessing type II microtubule-associated protein 1 (MAP1) light chain 3 (LC3) and Beclin 1 expression levels relative to β-actin. Results indicated an increased ratio of LC3-II to β-actin in splenocytes of C57BL/6 mice only at 7 day post infection (d.p.i.) compared to uninfected animals. LC3-II/β-actin and Beclin 1/β-actin ratios in splenocytes of BALB/c mice increased at 5 d.p.i. and remained high until day 14 and 7 p.i., respectively. We confirmed the formation of autophagosome structures in the spleen of BALB/c mice by transmission electron microscopy (TEM). Moreover, autophagy accompanied necrosis in the splenocytes of infected animals. Results suggest that ECTV-MOS induced autophagy, especially in the spleen of the susceptible mouse strain, may support viral replication and promote cell necrosis.

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“…2 and 3). Parker et al (2009) have shown that following f.p. infection of C57BL/6 mice with 100 PFU f.p.…”

Section: Discussionmentioning

confidence: 99%

In vivo induction of autophagy in splenocytes of C57BL/6 and BALB/c mice infected with ectromelia orthopoxvirus

Martyniszyn

Szulc-Dąbrowska

Boratyńska-Jasińska

et al. 2013

Polish Journal of Veterinary Sciences

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“…Deletion of genes encoding WV-specific proteins in VACV, such as A36, B5, and A34, also lead to highly attenuated infections in mice (21,38,51,71). The intranasal route of inoculation used in most of these studies mimics large-droplet transmission of smallpox in humans, leading to a systemic disease that shares similarities with smallpox disease progression (3,46,50). However, intranasal infection of mice with VACV WR requires large doses (10 4 to 10 6 PFU) to achieve substantial mortality (21,38,51), which may not be reflective of the doses of variola virus required to cause disease and death in humans.…”

Section: Discussionmentioning

confidence: 99%

Loss of Cytoskeletal Transport during Egress Critically Attenuates Ectromelia Virus Infection In Vivo

Lynn

Horsington

Ter

et al. 2012

J Virol

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d Egress of wrapped virus (WV) to the cell periphery following vaccinia virus (VACV) replication is dependent on interactionswith the microtubule motor complex kinesin-1 and is mediated by the viral envelope protein A36. Here we report that ectromelia virus (ECTV), a related orthopoxvirus and the causative agent of mousepox, encodes an A36 homologue (ECTV-Mos-142) that is highly conserved despite a large truncation at the C terminus. Deleting the ECTV A36R gene leads to a reduction in the number of extracellular viruses formed and to a reduced plaque size, consistent with a role in microtubule transport. We also observed a complete loss of virus-associated actin comets, another phenotype dependent on A36 expression during VACV infection. ECTV ⌬A36R was severely attenuated when used to infect the normally susceptible BALB/c mouse strain. ECTV ⌬A36R replication and spread from the draining lymph nodes to the liver and spleen were significantly reduced in BALB/c mice and in Rag-1-deficient mice, which lack T and B lymphocytes. The dramatic reduction in ECTV ⌬A36R titers early during the course of infection was not associated with an augmented immune response. Taken together, these findings demonstrate the critical role that subcellular transport pathways play not only in orthopoxvirus infection in an in vitro context but also during orthopoxvirus pathogenesis in a natural host. Furthermore, despite the attenuation of the mutant virus, we found that infection nonetheless induced protective immunity in mice, suggesting that orthopoxvirus vectors with A36 deletions may be considered another safe vaccine alternative.T he crowded, densely packed cytoplasm presents a significant hurdle to the subcellular transport of viruses, both in the translocation of viruses to their site of replication following cell entry and in the subsequent egress of progeny viruses to the cell periphery (16,18,29,69,70). This hurdle is most acute for large double-stranded DNA (dsDNA) viruses such as those belonging to the orthopoxvirus genus, which includes variola virus (VARV) and ectromelia virus (ECTV), the causative agents of smallpox and mousepox, respectively, and the prototypical orthopoxvirus, vaccinia virus (VACV). These viruses have a complicated replication cycle that has been studied best at the cellular level with VACV. Vaccinia virus replication produces two infectious forms: mature intracellular virus (MV), which has a single membrane and is generated at the so-called virus factory; and wrapped virus (WV), which is derived from MV and acquires an additional double membrane at the trans-Golgi network or early endosome compartment (33, 58). While it is apparent that microtubule transport plays a critical role at multiple stages during VACV replication, the stage best characterized at the molecular level is the transport of WV from the trans-Golgi network to the cell periphery (27,32,57,75,76). Once there, WV fuse with the plasma membrane and are released either directly or following the transient activation of actin-based motility ...

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“…In summary, advantages to using a murine MPXV model for therapeutic development include: (i) biomarkers of disease progression have been established in the mousepox model and can be readily applied to the MPXV stat1 Ϫ/Ϫ mouse model (38); (ii) reagents are readily available, and the biology and genetics of the mouse are well understood; (iii) early in the drug development plan, mice are invariably used to acquire efficacy, toxicity, and pharmacokinetic/pharmacodynamic data; and (iv) MPXV itself causes a natural disease in humans, unlike VACV and ECTV, which are used in other mouse models.…”

Section: Discussionmentioning

confidence: 99%

A Mouse Model of Lethal Infection for Evaluating Prophylactics and Therapeutics against Monkeypox Virus

Stabenow¹,

Buller²,

Schriewer³

et al. 2010

J Virol

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Monkeypox virus (MPXV) is an orthopoxvirus closely related to variola, the etiological agent of smallpox. In humans, MPXV causes a disease similar to smallpox and is considered to be an emerging infectious disease. Moreover, the use of MPXV for bioterroristic/biowarfare activities is of significant concern. Available small animal models of human monkeypox have been restricted to mammals with poorly defined biologies that also have limited reagent availability. We have established a murine MPXV model utilizing the STAT1-deficient C57BL/6 mouse. Here we report that a relatively low-dose intranasal (IN) infection induces 100% mortality in the stat1 ؊/؊ model by day 10 postinfection with high infectious titers in the livers, spleens, and lungs of moribund animals. Vaccination with modified vaccinia virus Ankara (MVA) followed by a booster vaccination is sufficient to protect against an intranasal MPXV challenge and induces an immune response more robust than that of a single vaccination. Furthermore, antiviral treatment with CMX001 (HDP-cidofovir) and ST-246 protects when administered as a regimen initiated on the day of infection. Thus, the stat1 ؊/؊ model provides a lethal murine platform for evaluating therapeutics and for investigating the immunological and pathological responses to MPXV infection.

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Mousepox in the C57BL/6 strain provides an improved model for evaluating anti-poxvirus therapies

Cited by 46 publications

References 39 publications

In vivo induction of autophagy in splenocytes of C57BL/6 and BALB/c mice infected with ectromelia orthopoxvirus

In vivo induction of autophagy in splenocytes of C57BL/6 and BALB/c mice infected with ectromelia orthopoxvirus

Loss of Cytoskeletal Transport during Egress Critically Attenuates Ectromelia Virus Infection In Vivo

A Mouse Model of Lethal Infection for Evaluating Prophylactics and Therapeutics against Monkeypox Virus

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