abstract: Host organisms have evolved multiple mechanisms to defend against a viral infection and likewise viruses have evolved multiple methods to subvert the host's anti-viral immune response. Vaccinia virus (VACV) is known to contain numerous proteins involved in blocking the cellular anti-viral immune response. The VACV E3L protein is important for inhibiting the anti-viral immune response and deletions within this gene lead to a severe attenuation. In particular, VACV containing N-terminal truncations in E3L are attenuated in animal models and fail to replicate in murine JC cells. Monkeypox virus (MPXV) F3L protein is a homologue of the VACV E3L protein, however it is predicted to contain a 37 amino acid N-terminal truncation. Despite containing an N-terminal truncation in the E3L homologue, MPXV is able to inhibit the anti-viral immune response similar to wild-type VACV and able to replicate in JC cells. This suggests that MPXV has evolved another mechanism(s) to counteract host defenses and promote replication in JC cells. MPXV produces less dsRNA than VACV during the course of an infection, which may explain why MPXV posses a phenotype similar to VACV, despite containing a truncated E3L homologue. The development of oncolytic viruses as a therapy for cancer has gained interest in recent years. Oncolytic viruses selectively replicate in and destroy cancerous cells and leave normal cells unharmed. Many tumors possess dysregulated anti-viral signaling pathways, since these pathways can also regulate cell growth. Creating a mutation in the N-terminus of the VACV-E3L protein generates an oncolytic VACV that depends on dysregulated anti-viral signaling pathways for replication allowing for direct targeting of the cancerous cells. VACV-E3Ldel54N selectively replicates in numerous cancer cells lines and not in the normal cell lines. Additionally, VACV-E3Ldel54N is safe and effective in causing tumor regression in a xenograph mouse model. Lastly, VACV-E3Ldel54N was capable of spreading from the treated tumors to the untreated tumors in both a xenograph and syngeneic mouse model. These data suggest that VACV-E3Ldel54N could be an effective oncolytic virus for the treatment of cancer. / Dissertation/Thesis / Ph.D. Microbiology 2010

The Orthopoxviruses (OPVs) comprise a group of viruses that possess very similar genomes; they vary considerably, however, in virulence. Among them, rabbitpox virus (RPXV) and monkeypox virus (MPXV) are the focus of this thesis. RPXV is closely related to vaccinia virus (VACV) but is significantly more virulent in rabbits. The West African isolates of MPXV, which also caused the human monkeypox 2003 outbreak in the USA. have different disease profiles from the Central African MPXV. To determine the basis for these differences, the complete genomes of RPXV-UTR and three West African isolates of MPXV were sequenced and analyzed. The result of the RPXV study indicates that 3 RPXV genes. alone or in combination. likely play a key role in the enhanced RPXV-UTR virulence over VACV isolates. These genes encode: the RING finger protein (RPXV-UTR 008), an ankyrin repeat family protein (RPXV-UTR 180) and the chemokine binding protein (RPXV-UTR 001/184) in the inverted terminal repeats (ITR) of RPXV. Examination of the evolutionary relationship between RPXV-UTR and other OPVs was carried out using the central DNA sequence of the genome that is conserved among all completely sequenced OPVs and also the protein sequences derived from the 49 genes present in all completely sequenced Chordopoxviruses (ChPV). The results of these analyses both confirm the hypothesis that RPXV-UTR is most similar to VACV. An animal study found that the Central African MPXV isolate is more virulent than the West African MPXV isolate. The comparison of the three West African isolates MPXV-COP-58. MPXV-SL-V70. and MPXV-WRAIR, and the Congo basin (Central Africa) isolate MPXV-ZAI-96-I-16 shows that the MPXV-ZAI-96-I-16 ORF D14L, which encodes an inhibitor of human complement, is most likely the virulence gene responsible for the pathogenesis differences between the West and Central African isolates. These results explain the lack of fatalities in the 2003 MPXV outbreak in the USA, which was caused by importation of a West African MPXV isolate.

abstract: Cell death is a powerful tool through which organisms can inhibit the spread of viruses by preventing their replication. In this work, I used viral and chemical stressors to elucidate the mechanisms by which one anti-viral system might be activated over another, focusing on the programmable death pathway necroptosis and Protein Kinase R (PKR). PKR can detect viral dsRNA and trigger antiviral effects such as cessation of translation and induction of programmed death. Necroptosis is a rapid cellular death that can be induced via sensors such as DNA-dependent activator of IFN-regulatory factors (DAI), also known as Z-DNA-binding protein 1 (ZBP1). DAI contains a Z-form nucleic acid (ZNA) binding domain. E3, the primary vaccinia virus (VACV) interferon resistance protein, contains a similar domain in its amino terminus. We have previously reported this domain to be necessary for the inhibition of both PKR activation and DAI/ZBP1-mediated necroptosis. Monkeypox virus is a reemerging human pathogen. Despite a partial amino-terminal deletion in its E3 homolog, it does not activate PKR. In chapter 2, I show that MPXV produces less dsRNA than VACV, which could explain how the virus avoids activating PKR. The amino-terminus of vaccinia is associated with ZNA binding, inhibition of PKR, and inhibition of necroptosis. To determine the roles of PKR inhibition and ZNA binding in necroptosis inhibition, I characterized the VACV mutants Za(ADAR1)-E3, which binds ZNA but does not inhibit PKR, and E3:Y48A, which cannot bind ZNA. I found that while Za(ADAR1)-E3 fails to induce necroptosis, E3:Y48A does not activate PKR but does induce necroptosis. This suggests that Z-form nucleic acid binding is not necessary for vaccinia E3-mediated inhibition of PKR, nor is the inhibition of PKR sufficient for the inhibition of necroptosis. Finally, all known ZNA-binding proteins have immune functions and home to stress granules. I asked if stress granule formation alone could lead to necroptosis. I found that in L929 cells sodium arsenite, a known inducer of stress granules, could trigger DAI-dependent necroptosis. This suggests that DAI/ZBP1 is not necessarily a sensor of viral ligands but perhaps is a sensor of stress signals brought about by infection. / Dissertation/Thesis / Doctoral Dissertation Biological Design 2018

acase@tulane.edu

Monkeypox virus (MPXV) is the causative agent of monkeypox (mpox), a rare viral disease that affects humans [1]. It is primarily found in Africa and is transmitted to humans through contact with sick animals, particularly rodents and monkeys, or through human-to-human transmission [2]. From the beginning of May 2022, cases of mpox have been recorded from non-endemic nations, and the illness has continued to be reported in other endemic nations. Majority of confirmed cases have been recorded in Europe and North America. In this thesis, we compare the spread of the outbreak across the top ten countries using a combination of two different techniques. First, we look at the similarity of the outbreak from a mathematical modeling point of view using a simple SIR model to describe the dynamics of the spread and compare parameters of the model among most prevalent countries. Using the model as the general trend of the outbreak, we then look at the spread from a clustering perspective, grouping countries based on a time-series clustering technique.

See front file / Health Studies / DLITT ET PHIL (HEALTH ST)

See front file / Health Studies / DLITT ET PHIL (HEALTH ST)