Phospholipid synthesis in Sindbis virus-infected cells

Area of Science:

• Virology
• Cell Biology
• Biochemistry

Background:

• Previous studies observed decreased phospholipid synthesis in chick embryo fibroblasts infected with Sindbis virus.
• The specific metabolic requirements for this observed inhibition were not fully understood.

Purpose of the Study:

• To investigate the metabolic requirements for Sindbis virus-induced inhibition of phospholipid synthesis.
• To determine the role of viral RNA and protein synthesis in this process.

Main Methods:

• Utilized (32)PO(4) and (14)C-choline incorporation to measure phospholipid synthesis.
• Employed temperature-sensitive Sindbis virus mutants to assess the necessity of viral RNA and protein synthesis.
• Compared effects of actinomycin D and cycloheximide on choline incorporation in infected and uninfected cells.

Main Results:

• Viral ribonucleic acid (RNA) synthesis was essential for inhibiting choline incorporation, but functional viral structural proteins were not.
• Inhibition of host cell RNA and protein synthesis preceded the decline in phospholipid synthesis.
• Actinomycin D and cycloheximide inhibited choline incorporation in uninfected cells, suggesting a broader impact on synthesis pathways.

Conclusions:

• The decrease in phospholipid synthesis during Sindbis virus infection is likely a secondary effect of viral inhibition of host cell RNA and protein synthesis.
• Viral RNA synthesis is a key factor in triggering these inhibitory effects.
• The response of phospholipid synthesis to Sindbis virus differs between cell types, with BHK cells showing late inhibition.