Biomedical subjects
Publications and source records attributed to T Dalianis.
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Polyoma virus induced tumorigenesis is controlled by T-cells, while B-cells clear virus infection. In order to study if T-cells can override the tumorigenic effect of a long term disseminated viral infection, the tumorigenicity and persistence of polyoma virus in antibody deficient adult and newborn infected X-linked immunodeficient (XID) and microMT mice was followed. In newborn infected XID and CBA control mice (sensitive to tumorigenesis), the frequency of tumor development was similar, and viral DNA was persistent at least 10 months p.i. In polyoma-infected newborn and adult microMT, and control C57BL/6 mice (resistant to tumorigenesis) as well as in adult XID and CBA control mice, no polyoma tumors were observed. Nevertheless, viral DNA was detected in most tissues in all microMT mice throughout the 5-7 month observation period, whereas in the remaining groups of mice persistent viral infection was limited or not detected. We suggest that the tumorigenic potential of an extensive persistent polyoma virus infection can be overcome as long as a functional T-cell system is present.
BACKGROUND: Human papilloma virus (HPV), which is frequently present in tonsillar carcinoma seems to be a prognostically favourable factor for patient survival and also for low risk of relapse. Since HPV may abrogate the function of wild type p53 and hence influence radiosensitivity we attempted to analyse if HPV and p53 status in tonsillar carcinoma affected tumour response to radiotherapy (RT) and patient survival. MATERIALS AND METHODS: Pre-treatment primary tonsillar carcinoma specimens were obtained retrospectively from 40 patients, 21 complete responders (CR) and 19 non-complete responders (non-CR) of which 38/40 were stage III and IV tumours. The paraffin-embedded biopsies were analysed for presence of HPV DNA, by general and type specific PCR, and for p53 overexpression by immunohistochemical staining with the murine Mab DO-1. RESULTS: It was possible to analyse HPV in 34 and p53 in 39 patients. Presence of HPV DNA (HPV+) and p53 immunostaining (p53+) were not correlated with response to RT, since 8/18 CR patients and 6/16 non-CR patients were HPV+ and 11/21 CR patients and 8/18 non-CR patients were p53+. A tendency towards a survival benefit in patients with HPV+ tumours was observed and this tendency was significant for patients with stage IV HPV + tumours (p = .0431), and in particular HPV+/p53- cancers (p = .0195). A difference in survival between patients with p53+ cancer as compared to patients with p53- lesions was not demonstrated. In conclusion, although presence of HPV and p53 immunoreactivity in tonsillar carcinoma could not be related to RT response, determination of HPV and p53 status may still prove useful as predictive/prognostic markers.
C.B-17 mice with the Severe Combined Immune Deficiency (SCID) mutation were infected with the naturally occurring murine polyomavirus. Using the Polymerase Chain Reaction (PCR) technique, persistence of polyomavirus was followed in different tissues of the mice between 24 hours and 2 months post infection (p.i.). Viral DNA appeared by 3-5 days and was detected in all studied organs by 3 weeks p.i. From 4 weeks to 2 months p.i. viral DNA was present at high levels in all studied organs in all of the animals. As controls normal C.B-17 and A/Sn mice were used. Viral DNA appeared by 2-4 days. The infection reached a peak around 1 week p.i. This was followed by a clearing stage and viral DNA was no longer detectable by 4-5 weeks p.i. Most organs studied with PCR were also examined histologically, but no lesions were observed. Consequently persistence and organ distribution of polyomavirus in adult SCID mice differs greatly from that in normal adult mice.
Biopsies from 34 patients with cancer of the head, neck or esophagus, 2 laryngeal papillomas, and 2 normal tonsils were analysed for human papillomavirus (HPV), Epstein Barr virus (EBV) genomes and mutated or elevated levels of p53. In 4 biopsies p53 was also analysed by DNA sequencing. HPV type 31 was found in one laryngeal cancer with normal p53 and HPV type 16 in two tonsil cancers with aberrant p53 expression. EBV was detected by PCR in 11 biopsies, but in situ hybridisation and immunohistochemistry, did not confirm this finding. Aberrant p53 expression was observed in approximately half of the tumours. These results support the involvement of both aberrant p53 expression and HPV in the aetiology of squamous cell carcinoma of the head and neck.
The importance of antibodies for elimination of polyomavirus infection and the prevention of virus induced oncogenesis was studied, X-linked immunodeficiency (XID) mice, IgM-/- single knockout and IgMI-/- CD8-/- double knockout mice, all defective in antibody production, and normal control mice were infected with polyomavirus as adults. The mice were followed for presence of polyoma DNA with a polyoma specific polymerase chain reaction (PCR) over 6 weeks post infection (p.i.), a time point at which polyomavirus DNA is no longer detected in normal adult infected mice. As expected, virus DNA was not detected in normal mice 6 weeks p.i. In both IgM-/- single knockout and IgM-/- CD8-/- double knockout mice a disseminated infection was still observed by 6 weeks p.i. and the latter group of mice succumbed around two months p.i. In XID mice, only one third of the mice were still positive for viral DNA 6 weeks p.i. No polyomavirus induced tumors were observed in any of the mice during the 2-4 month observation period.