Related Experiment Videos
In vitro host range of Autographa californica nucleopolyhedrovirus recombinants lacking functional p35, iap1 or iap2
Abstract:
We have examined the host range in different insect cell lines of Autographa californica nucleopolyhedrovirus (AcMNPV) recombinants lacking p35, iap1 or iap2. These genes encode, or are predicted to encode, anti-apoptotic proteins. Abrogation of p35 reduced the ability of AcMNPV to replicate in permissive cell lines derived from Spodoptera frugiperda insects by inducing apoptosis. In semi-permissive cell lines, such as Lymantria dispar and Spodoptera littoralis cells, we observed cytopathic effects after infection with AcMNPV but little virus production. Infection of these cells by AcMNPV lacking p35 resulted in apoptosis. However, p35-deficient viruses were still able to replicate normally in Trichoplusia ni, Mamestra brassicae and Panolis flammea cell lines. Disruption of AcMNPV iap1 and iap2 was found not to affect virus replication in any of the cell lines. It was also possible to disrupt both iap1 and iap2 in the same virus without loss of infectivity. A virus without iap1 and p35 demonstrated identical growth characteristics and host range to a virus lacking p35. We conclude that in cells which respond to AcMNPV infection by initiating programmed cell death, the p35 gene product alone is sufficient to inhibit apoptosis. Removal of iap1 or iap2 has no effect on virus replication, even in cell lines which do not undergo apoptosis in response to AcMNPV infection. Our results with two semi-permissive cell lines further indicate that whilst p35 is important in blocking block apoptosis, other factors are involved in restricting AcMNPV replication within these cells.
Insights
Autographa californica nucleopolyhedrovirus (AcMNPV) p35 gene inhibits apoptosis in insect cells. Deleting iap1 or iap2 genes did not impact AcMNPV replication or host range, suggesting p35 is key for viral survival.
Area of Science:
- Molecular Virology
- Insect Pathology
- Cell Biology
Background:
- Autographa californica nucleopolyhedrovirus (AcMNPV) is a baculovirus that infects insects.
- Apoptosis, or programmed cell death, is a defense mechanism insects use against viral infections.
- AcMNPV possesses genes, such as p35, iap1, and iap2, that encode anti-apoptotic proteins to counteract host defenses.
Purpose of the Study:
- To investigate the role of AcMNPV genes p35, iap1, and iap2 in viral replication and host range across different insect cell lines.
- To determine if these genes are essential for overcoming host-induced apoptosis.
- To understand the specific functions of p35, iap1, and iap2 in AcMNPV pathogenesis.
Main Methods:
- Generation of AcMNPV recombinants with deletions in p35, iap1, or iap2 genes.
- Infection of various permissive and semi-permissive insect cell lines (Spodoptera frugiperda, Lymantria dispar, Spodoptera littoralis, Trichoplusia ni, Mamestra brassicae, Panolis flammea).
- Assessment of viral replication, host range, and induction of apoptosis in infected cells.
Main Results:
- Abrogation of p35 significantly reduced AcMNPV replication in permissive Spodoptera frugiperda cells by inducing apoptosis.
- p35-deficient AcMNPV induced apoptosis in semi-permissive Lymantria dispar and Spodoptera littoralis cells, limiting virus production.
- Viruses lacking p35 replicated normally in Trichoplusia ni, Mamestra brassicae, and Panolis flammea cell lines.
- Disruption of iap1 and/or iap2 genes did not affect AcMNPV replication or host range in any tested cell lines.
- A virus lacking both iap1 and p35 showed similar growth and host range to a p35-deficient virus.
Conclusions:
- The p35 gene product is sufficient to inhibit apoptosis in insect cells that initiate programmed cell death upon AcMNPV infection.
- The iap1 and iap2 genes are not essential for AcMNPV replication or overcoming apoptosis, even in cell lines not undergoing apoptosis.
- While p35 is crucial for blocking apoptosis, other unidentified factors contribute to restricting AcMNPV replication in certain semi-permissive cell lines.