Orientdor: Octavio Henrique de Oliveira Pavan / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-07-21T06:05:21Z (GMT). No. of bitstreams: 1 Cavallaro_AngelaCristina_D.pdf: 5675160 bytes, checksum: ee36962431b2ffad76b6efb352af245e (MD5) Previous issue date: 1996 / Doutorado / Genetica / Doutor em Ciências Biológicas

Thesis (MMedVet (Medicine))--University of Pretoria, 2006. / Includes bibliographical references.

A Research Report submitted to the Faculty of Health Sciences, University of Witwatersrand, Johannesburg in part fulfillment of the requirements for the degree of Masters of Medicine in the branch of Haematology Johannesburg, / Parvovirus B19, a single stranded deoxyribose nucleic acid (DNA) virus, is known to cause anaemia in the setting of immune suppression such as Human Immunodeficiency Virus (HIV) infection. It is typically associated with a severe, isolated, normochromic normocytic anaemia and reticulocytopenia. The bone marrow classically shows a pure red cell aplasia (PRCA) with absence of maturing erythropoiesis, giant pronormoblasts and a variable presence of erythroid viral inclusions. Parvovirus B19 infection is a treatable cause of anaemia using red cell transfusions, intravenous immunoglobulin (Ig) therapy and in the setting of HIV, antiretroviral therapy. In the setting of HIV infection, testing for Parvovirus B19 infection using molecular techniques such as polymerase chain reaction (PCR) are preferred over serological methods, as antibodies are either not made or are dysfunctional. In South Africa, the prevalence of Parvovirus B19 infection in the HIV infected population with severe anaemia is not known. The aim of this study was to assess the prevalence of Parvovirus B19 in a cohort of HIV infected patients with severe anaemia. The Inclusion criteria for specimens into the study included all specimens submitted for a bone marrow examination submitted for routine diagnostic workup between January 2012 and November 2013 at two academic hospitals in Johannesburg. The study population included HIV infected patients with severe anaemia, defined as haemoglobin levels <8 g/dl for men and non-pregnant women. Real-time PCR using the PrimerDesign™ genesig® Kit for Human Parvovirus B19 (Southampton, United Kingdom) was performed on DNA extracted from bone marrow aspirate slides of these patients. The Parvovirus B19 results (qualitative and semi-quantitative values) were assessed in conjunction with various Parvovirus B19-related clinical and laboratory parameters obtained from the laboratory information system (LIS). The prevalence of Parvovirus B19 in this cohort of patients was 13.3% (19/143). PCR testing was possible even in samples that were suboptimal for morphological assessment, with 36.8% (7/19) of the Parvovirus B19 infection being observed in these samples. Of note, 31.6% (6/19) of the positive samples were not requested for Parvovirus B19 testing by the clinician or pathologist, indicating that it is being under diagnosed in this population. PRCA was not observed in all Parvovirus B19 positive samples, with a sensitivity and specificity of 60.0% and 85.1% respectively. Alternate causes of anaemia were present in 42.1% (8/19) of the Parvovirus B19 positive samples, including 21.1% (4/19) of cases which showed Mycobacterium Tuberculosis infection, 5.3% (1/19) with iron deficiency and 15.8% (3/19) of cases with marrow infiltration by malignancy. This highlights the importance of excluding Parvovirus B19 infection even in the setting of alternate causes of anaemia. In patients with severe anaemia and both HIV infection and Parvovirus B19-positivity, there was no statistically significant correlation between Parvovirus B19 viral load and HIV viral load, haemoglobin (Hb) level or CD4 count. Parvovirus B19 positivity was higher than expected in HIV virally suppressed patients, with a prevalence of 18.5% (5/27). However the CD4 counts in these samples were low (<350 cells/μl), suggesting that although viral suppression had been achieved, there was inadequate immune reconstitution to mount an effective humoral response to control the Parvovirus B19 infection. Serology for IgM as a method for diagnosing Parvovirus B19 infection showed poor sensitivity (60%) but good specificity (100%) suggesting that this is an inadequate screening test in the setting of HIV infection. The Parvovirus B19 positive samples had statistically significant lower reticulocyte production index (RPI) than the Parvovirus B19 negative samples. The negative predictive value of an RPI was 100%. Although this is a retrospective pilot study, notable findings were observed. In the setting of HIV infection and severe anaemia, Parvovirus B19 infection may be diagnosed by PCR even in the following scenarios: a negative IgM serology result, no morphological evidence of a PRCA, presence of other causes to explain the anaemia and confirmed HIV viral suppression. Parvovirus B19 is a treatable cause of anaemia and therefore an important entity to exclude. The cost of molecular diagnosis of parvovirus B19 is relatively higher than using serological methods, therefore should only be performed in the correct clinical setting. In HIV infected patients with grade four anaemia (Hb <6g/dl) and a reduced RPI, these findings support the use of molecular diagnosis for Parvovirus B19 infection regardless of other clinical and laboratory findings. / MT2017

Wild-type viruses with intrinsic oncolytic capacity in human includes DNA viruses like some autonomous parvoviruses and many RNA viruses. Recent advances in molecular biology have allowed the design of several genetically modified viruses, such as adenovirus and herpes simplex virus that specifically replicate in, and kill tumor cells. However, still several hurdles regarding clinical limitations and safety issues should be overcome before this mode of therapy can become of clinical relevance. It includes limited virus spread in tumor masses, stability of virus in the blood, trapping within the liver sinusoids, transendothelial transfer, and/or vector diffusion of viral particles to tumor cells, limited tumor transduction, immune-mediated inactivation or destruction of the virus. For replication-competent vectors without approved antiviral agents, suicide genes might be used as fail-safe mechanism. Cancer stem cells are a minor population of tumor cells that possess the stem cell property of self-renewal. Therefore, viruses that target the defective self-renewal pathways in cancer cells might lead to improved outcomes. In this thesis, data we generated in the field of oncolytic autonomous parvoviruses are presented. We replaced capsid genes by reporter genes and assessed expression in different types of human cancer cells and their normal counterparts, either at the level of whole cell population, (CAT ELISA) or at the single cell level, (FACS analysis of Green Fluorescent Protein). Cat expression was substantial (up to 10000 times background) in all infected tumor cells, despite variations according to the cell types. In contrast, no gene expression was detected in similarly infected normal cells, (with the exception of an expression slightly above background in fibroblasts.). FACS analysis of GFP expression revealed that most tumor cells expressed high level of GFP while no GFP positive normal cells could be detected with the exception of very few (less than 0.1%) human fibroblast cells expressing high level of GFP. We also replace capsid genes by genes coding for the costimulatory molecules B7-1 and B7-2 and show that, upon infection with B7 recombinant virions, only tumor cells display the costimulatory molecules and their immunogenicity was increased without any effect on normal cells. Using a recombinant MVM containig the Herpes Simplex thymidine kinase gene, we could get efficient killing of most tumor cell types in the presence of ganciclovir, whithout affecting normal proliferating cells. We also produced tetracycline inducible packaging cell lines in order to improve recombinant vectors yields. The prospects and limitations of these different strategies will be discussed. An overview is given of the general mechanisms and genetic modifications by which oncolytic viruses achieve tumor cell-specific replication and antitumor efficacy. However, as their therapeutic efficacy in clinical trials is still not optimal, strategies are evaluated that could further enhance the oncolytic potential of conditionally replicating viruses in conjunction with other standard therapies. Another exciting new area of research has been the harnessing of naturally tumor-homing cells as carrier cells to deliver oncolytic viruses to tumors. The trafficking of these tumor-homing cells (stem cells, immune cells and cancer cells), which support proliferation of the viruses, is mediated by specific chemokines and cell adhesion molecules and we are just beginning to understand the roles of these molecules. Finally, we will explore some ways deserving further study in order to be able to utilize various oncolytic viruses for effective cancer treatment.

Thesis (M.S.)--Auburn University, 2008. / Abstract. Includes bibliographical references (p. 33-36).

Thesis (MMedVet (Medicine)) - University of Pretoria, 2002. / Includes bibliographical references.

Thesis (M. Med. Sc.)--University of Hong Kong, 2000. / Includes bibliographical references (leaves 30-31).

Thesis (M.Med.Sc.)--University of Hong Kong, 2000. / Includes bibliographical references (leaves 30-31). Also available in print.

A dissertation submitted to the Faculty of Medicine, University of the Witwatersrand, in partial fulfilment of the requirements for the degree Master of Medicine (Virology) / This study was undertaken to determine the role of human parvovlrus B19 (B19) in chronic anaemia of HIV infected TB patients. Patlents were selected from an existing databank of 307 patients included in a MRC HIV/TB study. Twenty-nine patients, 15 colnfected with HIV /TB and 14 Infected with TB only, were identified for further evaluation. These patient's era were subjected to serological and DNA detection studies using IgG and IgM ELISA methods and a nested polymerase chain reaction (PCR) assay. The selection of the nested PCR was based on comparative evaluation of a new rapid 99 cycle PCR method recommended for hepatitis B DNA detection and the nested PCR method established for B19. The nested assay was shown to be the more sensitive system in the context of B19 DNA detection. Serological evaluation of these 29 patients suggested that a greater proportion of HIV/TB patients with chronic anaemia had evidence of recent or past exposure to B19 than those not experiencing anaemia. The nested PCR demonstrated the presence of circulating B19 DNA in 2 coinfected individuals with haematological pictures compatible with persistent B19 infection. B19 DNA was also demonstrated in a TB only patient without anaemia; further haematological and serological evidence in this patient suggested recent exposure to B19. The serological and DNA amplification assay results of these 29 patients would suggest a possible role - either causal or co-factorial - for persistent B19 infection in the establishment of chronic anaemia in HIV/TB patients. / Andrew Chakane 2019

Regensburg, Univ., Diss., 2009.