Chemie | Biochemie | Medizin
Lennart Horn, 2002 | Solothurn, SO
Parvovirus B19 (B19V) is a human pathogen with worldwide prevalence, causing fifth disease in children. A few studies investigated B19V targeting to the nucleus, however, the infectious pathway remains largely unknown. This study examined the influence of the Golgi-affecting drug Brefeldin A on the infectious pathway of B19V, measuring viral mRNA expression 24 hours post-infection. To exclude a deleterious effect of Brefeldin A on endo-lysosomal trafficking, the internalization of a B19V-mimicking construct was tracked using laser scanning microscopy. The results suggest that Brefeldin A significantly inhibits B19V infection at 2-4 hours post-infection. Experiments with the B19V-mimicking construct showed that endo-lysosomal trafficking was not affected. These two findings indicate that the infectious pathway of B19V involves the Golgi/ER network. Understanding the infectious pathway is important to develop antiviral drugs or virus-based gene therapy.
The goal of this study was to find out whether the Golgi apparatus and/or the endoplasmic reticulum are involved in the infectious pathway of parvovirus B19. In light of this, it should reveal whether Brefeldin A inhibits infection of parvovirus B19. Moreover, the possible effects of Brefeldin A on endolysosomal trafficking should be examined with the help of a second experiment.
Samples consisting of UT7/Epo suspension cells were treated with Brefeldin A for 2 hours at various times after the cells were infected with parvovirus B19. Furthermore, two samples representing the positive control were not treated with Brefeldin A, and two samples representing the negative control were frozen 1.5 hours after infection with B19V. The viral mRNA expression of all samples was measured 24 hours post-infection.
To investigate the effect of Brefeldin A on endolysosomal trafficking, a parvovirus B19-mimicking construct as well as a lysotracker were added onto two samples of UT7/Epo suspension cells. Only one sample was treated with Brefeldin A. 30 minutes post-infection, both samples were imaged using a laser scanning microscope.
The samples that were treated with Brefeldin A from 0 to 2 hours post-infection did not contain significantly less viral mRNA than the positive control. However, the infection was strongly inhibited in the samples that were treated with Brefeldin A from 2 to 4 hours post-infection. The viral mRNA of those samples measured up to approximately 1% of the quantity that was found in the positive control.
In both Brefeldin A treated and untreated cells, the parvovirus B19-mimicking construct was found to collocate with the lysotracker.
Since the virus can access lysosomes both in Brefeldin A treated and untreated cells, Brefeldin A does not affect endolysosomal trafficking, which is in line with previous studies. Building on the fact that Brefeldin A specifically destroys the Golgi apparatus and the endoplasmic reticulum, the findings suggest that parvovirus B19 depends on either one or both of them to successfully infect the cell.
Brefeldin A significantly inhibits a cellular infection with parvovirus B19. Since Brefeldin A specifically destroys the Golgi apparatus and the endoplasmic reticulum and does not affect endolysosomal trafficking, this shows that the Golgi apparatus and/or the endoplasmic reticulum are involved in the infectious pathway of parvovirus B19.
Würdigung durch den Experten
Prof. Dr. Eric Kübler
Herr Lennart Horn führte seine Arbeit zum Infektionsweg des Parvovirus B19, einem humanen Pathogen, auf sehr guten wissenschaftlichen Niveau durch. Er konnte aufgrund seiner erhaltenen Resultate mit der Substanz Brefeldin A die These aufstellen, dass der Infektionsweg über das Endoplamatische Retikulum sowie der Golgi-Apparat geht. Dieses neue Verständnis zur Infektion des Parvovirus B19 ist überaus wichtig im Hinblick auf eine Bekämpfung dieses Virus. Die Arbeit wurde in sehr wissenschaftlicher Form knapp aber dennoch ausführlich beschrieben.
Lehrerin: Christina Tardo-Styner