Related Experiment Videos
Human papillomavirus type 11 E1--E4 and L1 proteins colocalize in the mouse xenograft system at multiple time points
D R Brown1, J T Bryan, L Pratt
1Department of Medicine, Indiana University School of Medicine, Indianapolis 46202, USA.
Abstract:
The most abundant viral mRNA species in HPV 11-infected tissue consists of two exons, joining a segment of open reading frame (ORF) E1 to ORF E4, potentially encoding the E1--E4 protein. The L1 ORF encodes the major capsid protein of HPV. Our previous studies demonstrated colocalization of the HPV 11 E1--E4 and L1 proteins within the same cells of HPV 11-infected human foreskin implants grown in athymic mice (the mouse xenograft system) and removed 12 weeks after implantation. Prior studies have demonstrated E1--E4 transcripts early in infection and throughout the HPV 11-infected epithelium, while L1 transcripts are detected later, and in a subset of E1--E4 mRNA-positive differentiated epithelial cells. Therefore, E1--E4 protein may be produced at an earlier time point or in less differentiated cells than the L1 protein. To study these questions, athymic mice were implanted with HPV 11-infected human foreskin fragments. Mice were sacrificed at 1-week intervals beginning 2 weeks after implantation of tissue. The E1--E4 and L1 proteins colocalized to the same differentiated epithelial cells or to tight clusters of cells in differentiated epithelial layers of HPV 11-infected implants. The E1--E4 and L1 proteins were first detected 4 weeks after implantation. E1--E4 protein was detected in the region of the cell membrane and cytoplasm, and never in the nucleus. L1 protein was only detected in the nucleus. Both proteins were detected in implants containing high viral copy numbers. No specific histologic changes were uniformly associated with detection of these proteins. The tight coupling of the E1-E4 and L1 proteins at multiple time points suggests that expression of both proteins is necessary to complete the virus life cycle.
Insights
Human papillomavirus (HPV) 11 E1--E4 and L1 proteins are found together in differentiated cells of infected tissue. This co-expression suggests both viral proteins are essential for completing the HPV life cycle.
Area of Science:
- Virology
- Molecular Biology
- Immunology
Background:
- Human papillomavirus (HPV) 11 infection involves multiple viral proteins, including E1--E4 and L1.
- Previous studies indicated potential differences in the temporal and cellular expression patterns of E1--E4 and L1 proteins.
- Understanding the spatiotemporal expression of these proteins is crucial for deciphering the HPV life cycle.
Purpose of the Study:
- To investigate the cellular localization and temporal expression of HPV 11 E1--E4 and L1 proteins.
- To determine if E1--E4 and L1 proteins are co-expressed in the same cells during HPV infection.
- To assess the relationship between viral load and the expression of these proteins.
Main Methods:
- Human foreskin xenografts infected with HPV 11 were implanted into athymic mice.
- Samples were collected at weekly intervals starting from 2 weeks post-implantation.
- Immunohistochemistry was used to detect and localize E1--E4 and L1 proteins within the differentiated epithelial cells.
Main Results:
- Both E1--E4 and L1 proteins were first detected at 4 weeks post-implantation in differentiated epithelial cells.
- E1--E4 protein localized to the cell membrane and cytoplasm, while L1 protein was exclusively found in the nucleus.
- Co-localization of E1--E4 and L1 proteins was observed in the same cells and cell clusters, particularly in implants with high viral copy numbers.
Conclusions:
- The expression of HPV 11 E1--E4 and L1 proteins is tightly coupled in differentiated epithelial cells.
- The observed co-expression suggests that both proteins play a coordinated role in the HPV life cycle.
- Further research is needed to elucidate the specific functions of E1--E4 and L1 proteins during viral replication and assembly.