Mechanisms of cell entry by human papillomaviruses: an overview.

As the primary etiological agents of cervical cancer, human papillomaviruses (HPVs) must deliver their genetic material into the nucleus of the target cell. The viral capsid has evolved to fulfil various roles that are critical to establish viral infection. The particle interacts with the cell surface via interaction of the major capsid protein, L1, with heparan sulfate proteoglycans. Moreover, accumulating evidence suggests the involvement of a secondary receptor and a possible role for the minor capsid protein, L2, in cell surface interactions.The entry of HPV in vitro is initiated by binding to a cell surface receptor in contrast to the in vivo situation where the basement membrane has recently been identified as the primary site of virus binding. Binding of HPV triggers conformational changes, which affect both capsid proteins L1 and L2, and such changes are a prerequisite for interaction with the elusive uptake receptor. Most HPV types that have been examined, appear to enter the cell via a clathrin-dependent endocytic mechanism, although many data are inconclusive and inconsistent. Furthermore, the productive entry of HPV is a process that occurs slowly and asynchronously and it is characterised by an unusually extended residence on the cell surface.Despite the significant advances and the emergence of a general picture of the infectious HPV entry pathway, many details remain to be clarified. The impressive technological progress in HPV virion analysis achieved over the past decade, in addition to the improvements in general methodologies for studying viral infections, provide reasons to be optimistic about further advancement of this field.This mini review is intended to provide a concise overview of the literature in HPV virion/host cell interactions and the consequences for endocytosis.

Fine needle trucut biopsy in focal liver lesions: a reliable and safe method in identifying the malignant nature of liver lesions.

BACKGROUND AND STUDY AIMS: The correct management of a focal liver lesion, suspected of being malignant, requires tissue for histopathological examination. To this purpose an ultrasonically guided fine needle trucut biopsy technique (FNTCB) can be used, to allow obtaining large tissue samples. The aim of the study is to see that FNTCB is a reliable method in identifying the malignant or benign character of a focal liver lesion. PATIENTS AND METHODS: We retrospectively compared the results of 231 FNTCB of focal liver lesions with the final diagnosis. RESULTS: In 191 lesions a final diagnosis was obtained (164 were malignant, 27 were benign). In our series FNTCB has a sensitivity of 86.6% (142/164), a specificity of 100% (27/27) and an overall accuracy of 88.5% (169/191) in identifying malignancy. There was a correct identification in 79.4% (27/34) of primary liver tumours and 88.5% (115/130) of liver metastases. In 52% (60/115) of liver metastases the primary site was accurately suggested by the pathologist. Correct characterization of benign liver lesions was obtained in 63% (17/27) of the cases. The insufficient sample rate was 3.1% (6/191). In one patient with thrombocytopenia an intraabdominal haemorrhage occurred. CONCLUSIONS: FNTCB is a reliable and safe method in identifying the malignant nature of liver lesions. Due to the large tissue sample, insufficient sample rate is low and an accurate histological identification of benign lesions, primary liver malignancies and metastases can be made. In case of metastases it is often possible to determine the site of the primary tumour.