Despite the eradication of smallpox, poxviruses continue to cause human disease around the world. At the core of poxvirus replication is the efficient and accurate synthesis and repair of the viral genome. The viral DNA polymerase is critical for these processes. Acyclic nucleoside phosphonate (ANP) compounds that target the viral polymerase are effective inhibitors of poxvirus replication and pathogenesis. Cidofovir (CDV) is an ANP that inhibits vaccinia virus (VAC) DNA polymerase (E9) DNA synthesis and 3-to-5 exonuclease (proofreading) activities. We determined that point mutations in the DNA polymerase genes of ANP-resistant (ANPR) VAC strains were responsible for CDV resistance and resistance to the related compound, HPMPDAP. Although these resistant strains replicated as well as wild-type VAC in culture, they were highly attenuated in mice. The generation of ANPR VAC strains, in combination with our knowledge of how CDV inhibits E9 activities, allowed us to study the hypothesized role of E9 in catalyzing double-strand break repair through homologous recombination. We provide evidence that VAC uses E9 proofreading activity to catalyze genetic recombination through single-strand annealing reactions (SSA) in infected cells. Both the polarity of end resection of recombinant intermediates and the involvement of polymerase proofreading activity establish these poxviral SSA reactions as unique among homologous recombination schemes. Furthermore, we identified roles for the VAC single-stranded DNA-binding (SSB) protein and nucleotide pools in regulating these reactions. During these later studies we uncovered a differential requirement for the large and small subunits of the VAC ribonucleotide reductase (RR) in viral replication and pathogenesis. Our studies suggest that poxviral RR small subunits form functional complexes with host large RR subunits to provide sufficient nucleotide pools to support DNA replication. We present a model whereby interaction of VAC SSB and RR proteins at replication forks allows for modulation of E9 activity through local nucleotide pool changes, which serves to maximize replication rates while still allowing for recombinational repair. / Virology

Tübingen, Univ., Diss., 2008.

Thesis (Ph. D.)--Cornell University, 1989. / Vita. Includes bibliographical references.

Thesis (M.S.)--University of Florida, 2004. / Typescript. Title from title page of source document. Document formatted into pages; contains 51 pages. Includes Vita. Includes bibliographical references.

Thesis (Ph.D.)--University of Florida, 2005. / Typescript. Title from title page of source document. Document formatted into pages; contains 150 pages. Includes Vita. Includes bibliographical references.

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

To compare the efficacy and duration of the immune response to local and systemic vaccination, Balb/c mice were vaccinated either intraperitoneally (i.p.) with an inactivated A/PR/8/34 (H1N1) vaccine or intranasally (i.n.) with a vaccinia recombinant containing the H1 gene of influenza. The i.p. inactivated vaccine stimulated high serum IgG anti-influenza titres and protected the lungs against viral challenge for the duration of the experiment (17 months). Little nasal wash IgA was induced and the noses were susceptible to challenge. Animals vaccinated i.n. with the recombinant had lower serum IgG titres and the lungs showed poor protection against challenge. Nasal wash IgA titres were higher, however, and the noses were largely protected from viral challenge for 17 months.

No Brasil, casos de doença exantemática em bovinos e humanos têm sido relatados em diversas regiões, cujo agente causal é o virus vaccinia pertencente ao gênero Orthopoxirus da família Poxviridae. Classicamente, a varíola bovina é causada pelo Cowpoxvirus, entretanto, outros Poxvirus, como o vírus vaccinia podem desenvolver sintomatologia clínica semelhante. Além de comprometer a cadeia produtiva de leite, uma vez que dificulta a ordenha, predispõe a mastite e descarte do produto, é uma zoonose e atualmente está incluída no diagnóstico de doença vesicular. A origem desses casos bem como a epidemiologia da doença ainda é pouco conhecida. Assim, objetivou-se no presente estudo 1) Avaliar a soroprevalência de Orthopoxirus em rebanhos bovinos do circuito sete do Estado de São Paulo que compreendem as regiões do Vale do Paraíba e Mogi das Cruzes e associar os possíveis fatores de risco envolvidos na transmissão da doença; 2) Detectar e caracterizar a presença de Orthopoxirus em amostras suspeitas de doença vesicular, no período de 2007 a 2009, provenientes de diversas regiões do Brasil utilizando técnicas convencionais e moleculares: microscopia eletrônica, isolamento viral, PCR e RFLP; 3) Sequenciamento e análise filogenética das amostras positivas para o vírus vaccinia. Para o inquérito soroepidemiológico foram analisadas 76 propriedades pertencentes ao circuito 7 que compreendem as regiões do Vale do Paraíba e Mogi das Cruzes, estado de São Paulo, selecionadas aleatoriamente, totalizando 619 animais, estratificados em fêmeas acima de dois anos. A soroprevalência de Orthopoxirus no Vale do Paraíba foi de 32,3% (200/619) pela virusneutralização. Associação positiva foi encontrada para presença de animais silvestres. No diagnóstico virológico foram analisadas 227 amostras de epitélio, negativas para outras doenças vesiculares. Encontrou-se frequencia de 63,4% (144/227) positivas para o Orthopoxirus em praticamente todas as regiões do país. A análise por RFLP revelou perfil de padrão para o vírus vaccinia. O sequenciamento dos isolados confirmou que o vírus vaccinia é a estirpe circulante e está agrupado no grupo I de isolados de vaccinia brasileiros. / In Brazil, cases of rash illness in cattle and humans have been reported in several regions whose causal agent is the vaccinia virus belonging to the genus Orthopoxirus (OPV) family Poxviridae. Classically, cowpox is caused by Cowpoxvirus, however, other poxviruses such as vaccinia virus may develop same clinical signs. In addition to compromising the production chain of milk, as it hampers milking, predisposes to mastitis and discard the product, also it is a zoonosis and is currently included in the differential diagnosis of vesicular disease. The origin of these cases as well as the epidemiology of the disease is still unknown. Thus, the aim of the present study 1) assess the serum prevalence of OPV in cattle herds circuit seven Vale do Paraíba and associate the possible risk factors involved in disease transmission, 2) identify and characterize the presence of OPV in samples suspected vesicular disease in the period 2007-2009, from various regions of Brazil using conventional techniques and molecular electron microscopy, virus isolation, PCR and RFLP; 3) Sequencing and phylogenetic analysis of the samples positive for OPV. For epidemiological survey were analyzed 76 properties in the region of Vale do Paraíba, São Paulo, randomly selected, totaling 619 animals, stratified in females more than two years. The serum prevalence of OPV in the Paraíba Valley was 32.3% (200/619) by virus neutralization. Positive association was found for presence of wild animals. The virological diagnosis were analyzed 227 samples of epithelium, negative for other vesicular diseases. Met frequency of 63.4% (144/227) positive for OPV in practically all regions of the country. RFLP analysis revealed default profile for the vaccinia virus. The sequencing of the isolates confirmed that vaccinia virus strain is circulating and is clustered in group I isolates of Brazilians vaccinia.

No Brasil, casos de doença exantemática em bovinos e humanos têm sido relatados em diversas regiões, cujo agente causal é o virus vaccinia pertencente ao gênero Orthopoxirus da família Poxviridae. Classicamente, a varíola bovina é causada pelo Cowpoxvirus, entretanto, outros Poxvirus, como o vírus vaccinia podem desenvolver sintomatologia clínica semelhante. Além de comprometer a cadeia produtiva de leite, uma vez que dificulta a ordenha, predispõe a mastite e descarte do produto, é uma zoonose e atualmente está incluída no diagnóstico de doença vesicular. A origem desses casos bem como a epidemiologia da doença ainda é pouco conhecida. Assim, objetivou-se no presente estudo 1) Avaliar a soroprevalência de Orthopoxirus em rebanhos bovinos do circuito sete do Estado de São Paulo que compreendem as regiões do Vale do Paraíba e Mogi das Cruzes e associar os possíveis fatores de risco envolvidos na transmissão da doença; 2) Detectar e caracterizar a presença de Orthopoxirus em amostras suspeitas de doença vesicular, no período de 2007 a 2009, provenientes de diversas regiões do Brasil utilizando técnicas convencionais e moleculares: microscopia eletrônica, isolamento viral, PCR e RFLP; 3) Sequenciamento e análise filogenética das amostras positivas para o vírus vaccinia. Para o inquérito soroepidemiológico foram analisadas 76 propriedades pertencentes ao circuito 7 que compreendem as regiões do Vale do Paraíba e Mogi das Cruzes, estado de São Paulo, selecionadas aleatoriamente, totalizando 619 animais, estratificados em fêmeas acima de dois anos. A soroprevalência de Orthopoxirus no Vale do Paraíba foi de 32,3% (200/619) pela virusneutralização. Associação positiva foi encontrada para presença de animais silvestres. No diagnóstico virológico foram analisadas 227 amostras de epitélio, negativas para outras doenças vesiculares. Encontrou-se frequencia de 63,4% (144/227) positivas para o Orthopoxirus em praticamente todas as regiões do país. A análise por RFLP revelou perfil de padrão para o vírus vaccinia. O sequenciamento dos isolados confirmou que o vírus vaccinia é a estirpe circulante e está agrupado no grupo I de isolados de vaccinia brasileiros. / In Brazil, cases of rash illness in cattle and humans have been reported in several regions whose causal agent is the vaccinia virus belonging to the genus Orthopoxirus (OPV) family Poxviridae. Classically, cowpox is caused by Cowpoxvirus, however, other poxviruses such as vaccinia virus may develop same clinical signs. In addition to compromising the production chain of milk, as it hampers milking, predisposes to mastitis and discard the product, also it is a zoonosis and is currently included in the differential diagnosis of vesicular disease. The origin of these cases as well as the epidemiology of the disease is still unknown. Thus, the aim of the present study 1) assess the serum prevalence of OPV in cattle herds circuit seven Vale do Paraíba and associate the possible risk factors involved in disease transmission, 2) identify and characterize the presence of OPV in samples suspected vesicular disease in the period 2007-2009, from various regions of Brazil using conventional techniques and molecular electron microscopy, virus isolation, PCR and RFLP; 3) Sequencing and phylogenetic analysis of the samples positive for OPV. For epidemiological survey were analyzed 76 properties in the region of Vale do Paraíba, São Paulo, randomly selected, totaling 619 animals, stratified in females more than two years. The serum prevalence of OPV in the Paraíba Valley was 32.3% (200/619) by virus neutralization. Positive association was found for presence of wild animals. The virological diagnosis were analyzed 227 samples of epithelium, negative for other vesicular diseases. Met frequency of 63.4% (144/227) positive for OPV in practically all regions of the country. RFLP analysis revealed default profile for the vaccinia virus. The sequencing of the isolates confirmed that vaccinia virus strain is circulating and is clustered in group I isolates of Brazilians vaccinia.

Vaccinia virus (VACV) is primarily known as a vaccine against its relative variola virus, the causative agent of smallpox. In the seventies of the 20th century, the vaccination campaign with VACV led to eradication of smallpox. Consequently, vaccination of the general population was stopped. Currently, the vaccination was reintroduced, namely among army and healthcare professionals. However, vaccination with VACV is accompanied with a high incidence of vaccination-related complications, namely among immunocompromised individuals. One of the complications is eczema vaccinatum, occuring in patients with atopic dermatitis. The laboratory of Dr. Melkova has focused on development of a model of eczema vaccinatum in mice Nc/Nga and on studies of pathogenesis of this complication. The goal of my diploma thesis is to contribute to characterization of imunopathogenesis of eczema vaccinatum in mice Nc/Nga infected either with VACV strain Western Reserve (WR) or with a recombinant VACV with the integrated cDNA for IRF-3 (Interferon Regulatory Factor 3; WR-IRF3). IRF-3 regulates the expression of interferon type I in response to viral infection. This recombinant virus has been constructed in the laboratory of Dr. Melková. The objective of my work was to verify the expression of the integrated cDNA for IRF-3 and to...