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Changes in the nucleoprotein complexes of a baculovirus DNA during infection
Abstract:
The nature of the DNA-protein complexes assumed by Autographa californica nuclear polyhedrosis virus (AcNPV) DNA during infection of Spodoptera frugiperda cells was investigated by micrococcal nuclease digestion of infected nuclei. Both parental viral DNA and progeny viral DNA assumed a chromatin-like structure early in infection. By late times (24 hr) p.i., the viral DNA acquired a unique nucleoprotein structure. In addition to fragments of mononucleosome size (185 bp), two subnucleosomal bands of 120 and 90 bp were observed. The subnucleosomal bands contained exclusively viral DNA. No alteration in the nature of the host chromatin structure following AcNPV infection was observed. An examination of the basic chromatin-associated proteins revealed two major viral-induced proteins having molecular weights of 15K and 39K. The induction of the basic 15K protein between 10 and 24 hr p.i. coincided with the appearance of the altered nucleoprotein structure observed by 24 hr p.i. and the cessation of histone synthesis.
Insights
Autographa californica nuclear polyhedrosis virus (AcNPV) DNA forms a chromatin-like structure in infected cells. By late infection, viral DNA adopts a unique nucleoprotein structure with viral-induced proteins.
Area of Science:
- Molecular Virology
- Cellular Biology
- Epigenetics
Background:
- Autographa californica nuclear polyhedrosis virus (AcNPV) is a baculovirus that infects insect cells.
- Understanding viral DNA organization within host cells is crucial for comprehending viral replication and pathogenesis.
Purpose of the Study:
- To investigate the DNA-protein complexes formed by AcNPV DNA during infection of Spodoptera frugiperda cells.
- To characterize the nucleoprotein structure of viral DNA at different stages of infection.
- To identify viral-induced proteins associated with viral DNA.
Main Methods:
- Micrococcal nuclease digestion of infected nuclei.
- Analysis of DNA fragments by gel electrophoresis.
- Identification of viral-induced proteins using molecular weight determination.
Main Results:
- Both parental and progeny viral DNA adopted a chromatin-like structure early in infection.
- At late infection times (24 hr p.i.), viral DNA exhibited a unique nucleoprotein structure with mononucleosome-sized fragments (185 bp) and subnucleosomal bands (120 bp, 90 bp).
- Two major viral-induced proteins (15K and 39K) were identified, with the 15K protein's induction correlating with the altered nucleoprotein structure and cessation of histone synthesis.
Conclusions:
- AcNPV DNA undergoes significant structural changes during infection, forming a unique nucleoprotein complex.
- Viral-induced proteins, particularly the 15K protein, play a role in establishing this altered viral DNA structure.
- Host chromatin structure remains unaffected by AcNPV infection.