Department of Obstetrics and Gynaecology University of the Witwatersrand Johannesburg February 2015 A research report submitted to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Masters in Medicine, in the branch of Obstetrics and Gynaecology. / HIV accelerates the development of cervical cancer by up to15 years. South Africa is currently in the midst of an HIV epidemic. With limited facilities for colposcopy it is vital to identify risk factors within the HIV positive population resulting in positive margins after Large Loop Excision of the Transformation Zone (LLETZ) and persistence of cytological abnormalities on follow-up Pap smears. Objective: The primary objective was to determine the patient risk factors, pre and during colposcopy and LLETZ biopsy, which resulted in the histological involvement of margins of the LLETZ biopsy and persistent cervical dysplasia on follow-up Pap smears. Secondary objectives included determining follow up rate of patients at the clinic as well as the correlation between the original Pap smear cytology grade and the histological grade found on histology of the LLETZ biopsy. Methods: A retrospective review of the files of HIV seropositive patients was done at the colposcopy clinic at Charlotte Maxeke Johannesburg Academic Hospital after the roll out of antiretroviral treatment for the period 1 April 2004 to 31 October 2012. Patients with abnormal pap smears during this time were referred to the colposcopy clinic where a colposcopy and LLETZ biopsies were done. Demographic and clinical data in regards to age, gravidity, contraception, CD4 count, antiretroviral usage, and referral time was collected. Data from the clinical description of the colposcopy and histology of the LLETZ biopsy was also collected. Patients followed up again after 6 months when a repeat pap smear was done. The results of these Pap smears were also collected. Data was then analysed and variate and multivariate logistical regression was used to find statistically significant correlations. Results: A total of 480 files were found to have complete clinical records. One hundred and sixty eight (42.71%) patients had both endo and ectocervical margins clear. Predictive factors for the involvement of endocervical margins was the doctor performing the procedure (p-value <0.01) cytology of the original Pap smear (p value <0.01) and the grade of histological abnormality found at time of LLETZ (p-value <0.01). The statistically significant predictive factors for ectocervical margin involvement was the visualization of the transformation zone at colposcopy (p-value <0.01), the size of lesion found at colposcopy (p-value <0.01), the use of combined oral contraceptive pill (OCP) (p-value 0.02) and the histological grade of abnormality found on the LLETZ biopsy. Age, parity, CD4 count, use of antiretroviral drugs, length of time from Pap smear to colposcopy and use of contraception other than OCP were not found to be statistically significant in our sample population for the involvement of either endo or ectocervical margins. Statistically significant risk factors for the recurrence of intraepithelial lesions on follow up Pap smear was having both endo and ectocervical margin involvement on histology (p-value 0.01) The Ectocervical margin alone was found to have a p-value of <0.01. Abnormal cytology on follow up Pap smear was found in 58.69% of patients. The follow up rate at the clinic was 46.04%. Correlation of cytological grade and histological grade of cervical intraepithelial neoplasm in our sample population was found to be adequate (p-value <0.01). Conclusion: Incomplete incision of the intraepithelial lesion was found to be a significant risk factor for the recurrence of cytological abnormality in patients undergoing LLETZ biopsy. Identifying patients at increased risk for recurrence is important to ensure close follow up in this patient population.

An effective and safe vaccine against Hepatitis B virus already exists, yet morbidity and mortality of this illness are still high. The key to developing a reliable treatment is a deep knowledge of the virus' life cycle and functions of all its components. In the presented work we explored an interactome of the Core protein of the Hepatitis B virus. Using proximity-dependent biotin identification technique (BioID) coupled to mass spectrometry we have identified a list of potential candidates that are either significantly enriched (in total 105 proteins) or less abundant in the presence of the HBV Core protein in the cell (40 proteins). The list also includes known HBV Core interacting proteins SRPK1 and SRPK2, and p53 protein whose expression is known to be repressed due to the HBV Core interaction with the E2F1 transcription factor. Many of the newly identified possible HBV Core interacting proteins are involved in biological processes already known or are suspected to be influenced by the HBV such as translational and transporting processes or gene expression and macromolecule production. Overall, this work comprehensively characterizes the interaction landscape of the HBV Core protein in the live cells and might thus serve as a reliable start for in depth HBV-host interaction analysis. Key...

Human Caprin-1 and Caprin-2 are prototypic members of the caprin (cytoplasmic activation/proliferation-associated protein) protein family. Vertebrate caprin proteins contain two highly conserved homologous regions (HR1 and HR2) and C-terminal RGG motifs. Drosophila caprin (dCaprin) shares HR1 and RGG motifs but lacks HR2. Caprin-1 and Caprin-2 have important and non-redundant functions. The detailed molecular mechanisms of their actions remain largely unknown.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2007. / Härtill 4 uppsatser.

Core protein of aggrecan has a significant share on the correct function of articular cartilage. Its lack or structural failure could be the reason for the disfunction of the cartilage. The culture of chondrocytes taken from a pork articular cartilage was used for the study of aggrecan production. The monolayer culture method offers the model system which has enabled us to watch the aggrecan production into growth medium. The aggrecan synthesis was stimulated in the media with addition of L-methionin, L-serin and sodium selenite pentahydrate. Methionin and serin are antecedents of sulphur amino acid of cysteine, whose role is incredibly important for the correct function of core protein. Growth media and chondrocytes were analysed with the help of the automatic amino acids analyzer unit after acid or oxidative hydrolysis. The analyse established the amino acid representation. The main attention was paid to cysteine. The changing concentrations of this amino acid were showing if the antecedents in the addition are used for its production and, therefore, if it is possible to stimulate the production of core protein with these antecedents. The results are discussed in the conclusion of this thesis. The next step should be the detection of the concentration of synthesized aggrecan by the immunological method. Presently this method is very expensive. Therefore, the method of setting the core protein of aggrecan with the help of suitable amino acid was used for the first tests.

Hepatitis C virus (HCV) is remarkable for its ability to establish persistent infection. Studies suggest that HCV core protein modulates immune responses to viral infection and can bind Fas receptor in vitro. To further examine the role of HCV core protein in Fas signaling, full-length (aa 1-192) and truncated (aa 1-152) HCV core proteins were expressed in Jurkat lymphocytes and cells were assayed for apoptotic response, caspase activation, and Fas activation. Jurkat expressing full-length but not truncated core protein exhibited ligand-independent apoptosis. Cytoplasmic targeting of truncated core protein recapitulated its ability to induce apoptosis. Activation of caspases 8 and 3 was necessary and sufficient for full-length core to induce apoptosis. Jurkat cells expressing full-length but not truncated core protein induced Fas receptor aggregation. HCV core activates apoptotic pathways in Jurkat via Fas and requires cytoplasmic localization of core. Infection of host lymphocytes by HCV may alter apoptotic signaling and skew host responses to acute infection.

In 1989 the hepatitis C virus was identified as a significant cause of post-transfusion hepatitis. Nearly two decades later there is still no vaccine, inadequate treatment options, and limited understanding of how the virus establishes chronicity in the majority of the people it infects. Recent reports suggest that the interaction of a negative co-stimulatory pathway mediated by PD-1 and PDL-1 is associated with persistent viral infection. The role, if any, that PD-1/PDL-1 has in HCV infection is unknown. In this study we report that PD-1 is upregulated in T-cells from persons with chronic HCV infection when compared to healthy donors. In addition, PD-1 and PDL-1 are upregulated on T-cells from healthy donors when exposed to extracellular HCV core protein (a nucleocapsid protein that is immunosuppressive); upregulation of PD-1 is mediated by core's ability to bind to the complement receptor gC1q. We also report that the observed T-cell function can be restored by blocking the PD-1/PDL-1 interaction. Our results indicate that HCV core can upregulate an important negative T-cell signaling pathway that is associated with viral persistence. This upregulation of PD-1/PDL-1 represents a novel and perhaps shared mechanism that viral pathogens may use to subvert the human immune response. It also represents a potential new treatment option for the millions of people who suffer from chronic hepatitis C infection.

Η πολυλειτουργική πρωτεΐνη core του ιού της ηπατίτιδας C (HCV) εμπλέκεται στην ανάπτυξη ηπατοκυτταρικού καρκινώματος (HCC) που προκαλείται από τον ιό της ηπατίτιδας C, αλλά ο μηχανισμός με τον οποίο συμβαίνει αυτό δεν είναι κατανοητός. Η ενεργοποίηση του μονοπατιού Wnt/ β-κατενίνη, παίζει ένα σημαντικό ρόλο στην ανάπτυξη ηπατοκυττταρικού καρκίνου, και τροποποιείται από την πρωτεΐνη core του ιού της ηπατίτιδας C. Ο ιός της ηπατίτιδας C χαρακτηρίζεται από εκτεταμένη γενετική ποικιλομορφία και διαφορετικά κλινικά δείγματα διαφέρουν όσον αφορά την μολυσματικότητα τους και την παθογένεια που προκαλούν. Σκοπός αυτής της μελέτης είναι να καθοριστεί ο ρόλος της γενετικής ποικιλομορφίας της πρωτεΐνης HCV core στην ενεργοποίηση του μονοπατιού Wnt/ β-κατενίνη και να μελετηθεί ο μοριακός μηχανισμός με τον οποίο η πρωτεΐνη HCV core ρυθμίζει την ενεργοποίηση αυτή. Η ενεργότητα του μονοπατιού Wnt/β-κατενίνη μελετήθηκε σε HEK 293T και Huh 7.5 κυτταρικές σειρές που εκφράζουν παροδικά τις πρωτεΐνες core των γενοτύπων 1a, 1b, 3a, 4a, 4f και από ένα μοναδικό δείγμα του γενοτύπου 1a που προέρχεται από έναν ασθενή από την Καμπότζη (1aCam). Μελέτες βασισμένες στη μέτρηση ενεργότητας της λουσιφεράσης, Western blot ανάλυση και qPCR, χρησιμοποιήθηκαν για την μέτρηση των επιπέδων έκφρασης γονιδίων και πρωτεϊνών. Βρέθηκε ότι η HCV core πρωτεΐνη ρυθμίζει θετικά την μεσολαβούμενη από τη β-κατενίνη Tcf-εξαρτώμενη ενεργότητα της λουσιφεράσης σε ένα γενοτυπο-εξαρτώμενο τρόπο. Σε συμφωνά με τα αποτελέσματα αυτά βρέθηκε ότι η πρωτεΐνη HCV core σταθεροποίει τα επίπεδα της β-κατενίνης, τόσο σε παροδικά μετασχηματισμένα κύτταρα, όσο και σε κύτταρα που μολύνονται με βακουλοϊούς που εκφράσουν τις πρωτεΐνες core των υποτύπων 4a και 4f. Τέλος, βρέθηκε ότι η πρωτεΐνη HCV core συμβάλει στην θετική ρύθμιση των γονιδίων c-myc, αξίνης και Tbx3, τα οποία είναι καθοδικά γονίδια στόχοι του μονοπατιού Wnt/β-κατενίνη και εμπλέκονται στην ανάπτυξη ηπατοκυτταρικού καρκινώματος. Συμπερασματικά, οι πρωτεΐνες HCV core διαφορετικών γενοτύπων του ιού ρυθμίζουν διαφορετικά το μονοπάτι σηματοδότησης Wnt/β-κατενίνη και η διαφορετική αυτή ρύθμιση μπορεί να σχετίζεται με ικανότητα των διαφόρων γενοτύπων του ιού της ηπατίτιδας C να επάγουν την ανάπτυξη ηπατοκυτταρικού καρκινώματος. / The multifunctional HCV core protein is implicated in the development of hepatocellular carcinoma (HCC) caused by HCV infection, but the underlying mechanism is not fully understood. Activation of the Wnt/ β-catenin pathway plays a major role in HCC and is modulated by the HCV core protein. HCV is characterized by extensive genetic diversity and different clinical isolates do vary in their infectivity and pathogenesis mainly due to variations in the structure/function relationships of individual viral proteins. The aim of this study is to determine the possible influence of genetic variability in HCV core protein in enhancing the Wnt/ β-catenin signaling activity and to elucidate the molecular mechanisms by which HCV core modulates activation of β-catenin. The Wnt/β-catenin activity was investigated in transiently transfected HEK 293T and Huh 7.5 cell lines transiently expressing HCV core proteins from HCV genotypes 1a, 1b, 4a, 4f and from a unique isolate of genotype 1a obtained from a Cambodian patient (1aCam). Luciferase-based reporter assay, Western blot, and qPCR, were used to measure gene and protein expression levels. We found that, HCV core protein upregulates β-catenin-mediated Tcf-dependent luciferase activity in a genotype specific manner. Consistent to these findings, HCV core stabilizes β-catenin levels. Finally, we showed that HCV core contributes to the upregulation of Tbx3 gene expression, a downstream target gene of Wnt/ β-catenin pathway contributing to HCC development. In conclusion, HCV core protein from different genotypes appears to differentially regulate the Wnt/β-catenin signaling pathway and this finding may contribute to different potential of HCV genotypes to induce HCC.

Si la découverte récente de la souche virale JFH1, capable de réaliser un cycle viral complet en culture cellulaire, a permis de mieux caractériser le déroulement de l’infection du virus de l’hépatite C VHC, de nombreux aspects de la biologie du virus demeurent méconnus. Parmi ceux-ci, les mécanismes gouvernant l’encapsidation de l’ARN génomique viral au sein des particules restent à élucider. Cette thèse décrit la mise point d’un système de mobilisation hétérologue permettant l’analyse de l’interaction de la protéine de capside Core avec l’ARN viral. Ce système nous a permis d’identifier les régions de la protéine impliquées dans la liaison au génome viral, tout en autorisant son transfert dans des cellules naïves. Cette approche de mobilisation dépendante de la Core est complétée d’une étude de recrutement hétérologue basée sur la reconnaissance de l’ARN du phage MS2 avec la protéine de manteau Coat. Cette stratégie novatrice permet le recrutement efficace des ARNs marqués tout en autorisant leur localisation cellulaire. / The advent of infectious molecular clones of Hepatitis C virus (HCV) has unlocked the understanding of HCV life cycle. However, packaging of the genomic RNA, which is crucial to generate infectious viral particles, remains poorly understood. To study packaging in vivo, we developed a novel heterologous system to evaluate the interactions of HCV Core capside with viral RNA. This system allowed us to pinpoint Core domains involved in RNA binding, and package and transfer HCV RNA into a lentiviral vector. Aside from this Core dependent recruitment, we engineered retoviral vectors to trans-package MS2-tagged RNAs using MS2 Coat protein interaction. This system allowed us to efficiently recruit MS2-tagged replicons into naive cells and offers the opportunity to visualize HCV RNAs in Huh7.5 cells.

L’hépatite B, causée par le virus de l’hépatite B (VHB), est responsable d’un à deux millions de morts chaque année dans le monde. Le VHB occasionne des lésions importantes au niveau du foie, pouvant amener à la cirrhose et au carcinome hépatocellulaire. Ce virus, de la famille des hepadnavirus, contient une capside formée de 240 copies d’une même protéine : la protéine core. Des biopsies de patients infectés par le VHB montrent que la protéine de capside se localise soit dans le noyau soit dans le cytoplasme des cellules infectées. On s’accorde à dire qu’une localisation majoritairement cytoplasmique est liée à une aggravation de la maladie. Nous avons observé que, dans des cellules HuH-7, la protéine core seule est nucléaire alors qu’en contexte viral, elle se localise dans le cytoplasme. Après avoir vérifié que nos observations ne sont pas dues aux conditions de culture des cellules, nous avons démontré que la relocalisation de core est due à des facteurs viraux : la polymérase virale grâce à son domaine TP ainsi que la Tige/Boucle  présente sur l’ARN prégénomique. La localisation de core est aussi influencée par l’état de phosphorylation de ses sérines 157, 170 et 172.Ainsi, nous avons pu montrer à quel point le trafic de core était complexe et qu’il était régulé par divers facteurs viraux et cellulaires. Ces travaux permettront une étude plus approfondie des régulations du trafic intracellulaire de la protéine core et ainsi de faire évoluer plus favorablement l’hépatite B chez les patients infectés. / Hepatitis B is a liver inflammation caused by the Hepatitis B virus (HBV). It is responsible of one to two millions deaths per year in the world. HBV is the cause of important liver damages and may lead to cirrhosis and hepatocellular carcinoma.HBV is a member of hepadnaviral family. It has a capsid composed of 240 copies of the same protein: the core protein. In literature, patients’ biopsies showed that capsid is found either in the nucleus or in the cytoplasm or both compartments of hepatocytes. In general, a cytoplasmic localization is related to an advanced state of the disease.In our study, we observed that in HuH-7 cells, core protein alone has a nuclear localization, whereas in viral context it is essentially found in the cytoplasm. We verified that these observations were not due to culture conditions. Then, we demonstrated that the cytoplasmic localization of core was due to viral factors. The viral polymerase is implied by its TP domain. The second component is the viral pregenomic RNA, by its Epsilon stem loop structure. At last, core localization is also influenced by the phosphorylation state of its serines 157, 170 and 172.Thus, we demonstrated that the core protein traffic is very complex and regulated by different viral and cellular factors. This work will further study the regulation of intracellular trafficking of the core protein and allow a better outcome for the infected patients.