Year: 2007
Type: dissertation
Abstract: Canine parvovirus (CPV) is roughly 26A in diameter and has a 5.3kb long single-stranded DNA genome. The very small genome subdues CPV strongly dependent on nuclear processes of the host cell, requiring actively dividing cells to replicate. Like most other DNA viruses, CPV replicates within the host cell nucleus. Promyelocytic leukaemia (PML) protein, found due to its involvement in acute promyelocytic leukaemia (APL), is a novel component postulated to participate in the cellular anti-viral defence. Its expression is induced in response to type II interferons, a major defence line against viral infections. PML is the defining constituent of nuclear structures known as nuclear domain 10 (ND10), Kramer bodies, PML oncogenic dots (POD) or simply PML nuclear bodies (PML-NB). PML-NBs are dynamic structures known to respond to cellular stress, but whose exact function has been under rigorous debate. Nonetheless, many viruses, including CPV, are localized near PML-NBs in the course of infection and viruses have evolved diverse methods to disrupt PML-NBs. However, evidence for the significance of the virus-PML-NB co-localization is in some part contradictory. Here, we describe the use of confocal microscopy to define the effect of CPV infection on PML-NB dynamics. Two methods are emphasized in particular: fluorescence recovery after photobleaching (FRAP) and four-dimensional (4D) imaging. CPV appeared to have no significant effect on PML-NB dynamics. Average number, size and speed, all remained roughly the same in infected cells (p=0.166, p=0.389 and p=0.113, respectively). A borderline insignificant increase in the amount of PMLNBs moving over 50nm/s was however revealed (p=0.052), a very mild response considering what other viruses are capable of. The lack of significant effect may suggest CPV not being susceptible for PMLmediated anti-viral effects, or circumventing them by yet unknown mechanism. It may also hint for another role for PML-NBs in CPV infection, i.e. that of viral replication. It is the NS1 protein, important factor in viral replication, that was followed to the PML-NBs. Using FRAP we showed PML IV to be fully mobile within the nucleus, although the half time of recovery (tD) of 158 seconds suggests rather tight binding interactions. Thorough data analysis was hindered however by too intense bleaching.
Author: Juha Laurila
Language: English
Topic: Virology and Viral Diseases
Subfield: Epidemiology
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W2271968000