Proteomics of Herpes Simplex Virus Type 1 Nuclear Capsids

Area of Science:

• Virology
• Molecular Biology
• Proteomics

Background:

• Herpes simplex virus (HSV) assembly occurs in the nucleus, producing procapsids that mature into distinct nuclear capsid types (A, B, and C).
• Differences between HSV-1 A-, B-, and C-nuclear capsids and their protein compositions remain incompletely understood.
• Understanding capsid composition is crucial for elucidating viral egress mechanisms and nuclear envelope traversal.

Purpose of the Study:

• To investigate and compare the proteomic profiles of purified HSV-1 A-, B-, and C-nuclear capsids.
• To identify viral tegument and host proteins associated with different HSV-1 capsid types.
• To validate findings using mutant viruses and explore the utility of flow virometry for capsid purification.

Main Methods:

• Proteomics analysis of highly enriched HSV-1 A-, B-, and C-nuclear capsids.
• Purification of C-capsids using a novel flow virometry approach.
• Validation of proteomic data using pUL25 or VP5 mutant viruses.

Main Results:

• Identified expected capsid components and several viral tegument proteins (pUL21, pUL36, pUL46, pUL48, pUL49, pUL50, pUL51, pUS10) in C-capsids.
• Detected numerous host proteins, including ribosomal proteins, hnRNPs, glycogen synthase, keratin-related proteins, fibronectin 1, and PCBP1, on capsids, some specific to C-capsids.
• Confirmed findings using mutant viruses, demonstrating the specificity of identified proteins and the reliability of flow virometry.

Conclusions:

• HSV-1 A-, B-, and C-nuclear capsids exhibit distinct protein compositions, including associated viral tegument and host factors.
• The identified proteins, particularly host proteins, may play roles in capsid assembly, nuclear egress, or other stages of the HSV-1 life cycle.
• Flow virometry is a powerful tool for purifying viral particles, facilitating detailed proteomic analysis and advancing herpesvirus research.