The murine gammaherpesvirus 68 M2 gene is required for efficient reactivation from latently infected B cells

• Type of Material: Article
• Authors: Jeremy Herskowitz, Emory University; Meagan A. Jacoby, Emory University; Samuel Speck, Emory University
• Language: English
• Date: 2005-02-01
• Publisher: American Society for Microbiology
• Publication Version: Final Published Version
• Copyright Statement: © 2005, American Society for Microbiology
• Final Published Version (URL): http://dx.doi.org/10.1128/JVI.79.4.2261-2273.2005
• Title of Journal or Parent Work: Journal of Virology
• ISSN: 0022-538X
• Volume: 79
• Issue: 4
• Start Page: 2261
• End Page: 2273
• Grant/Funding Information: This research was supported by NIH grants R01 CA43143, R01 CA95318, and R01 AI58057 to S.H.S.
• Keywords: Science & Technology; Virology; GAMMA-HERPESVIRUS INFECTION; SPLENIC LATENCY; T-CELLS; IN-VIVO; EPSTEIN-BARR-VIRUS; MODEL; VIROLOGY; MICE; 68 GENOME; PATHOGENESIS; Life Sciences & Biomedicine; IMMUNE-SYSTEM
• Research Categories: Health Sciences, General; Health Sciences, Immunology

Abstract

Murine gammaherpesvirus 68 (γHV68) infection of mice provides a tractable small-animal model system for assessing the requirements for the establishment and maintenance of gammaherpesvirus latency within the lymphoid compartment. The M2 gene product of γHV68 is a latency-associated antigen with no discernible homology to any known proteins. Here we focus on the requirement for the M2 gene in splenic B-cell latency. Our analyses showed the following. (i) Low-dose (100 PFU) inoculation administered via the intranasal route resulted in a failure to establish splenic B-cell latency at day 16 postinfection. (ii) Increasing the inoculation dose to 4 × 10 5 PFU administered via the intranasal route partially restored the establishment of B-cell latency at day 16, but no virus reactivation was detected upon explant into tissue cultures. (iii) Although previous data failed to detect a phenotype of the M2 mutant upon high-dose intraperitoneal inoculation, decreasing the inoculation dose to 100 PFU administered intraperitoneally revealed a splenic B-cell latency phenotype at day 16 that was very similar to the phenotype observed upon high-dose intranasal inoculation. (iv) After low-dose intraperitoneal inoculation, fractionated B-cell populations showed that the M2 mutant virus was able to establish latency in surface immunoglobulin B-negative (sIgD - ) B cells; by 6 months postinfection, equivalent frequencies of M2 mutant and marker rescue viral genome-positive sIgD - B cells were detected. (v) Like the marker rescue virus, the M2 mutant virus also established latency in splenic naive B cells upon low-dose intraperitoneal inoculation, but there was a significant lag in the decay of this latently infected reservoir compared to that seen with the marker rescue virus. (vi) After low-dose intranasal inoculation, by day 42 postinfection, latency was observed in the spleen, although at a frequency significantly lower than that in the marker rescue virus-infected mice; by 3 months postinfection, nearly equivalent levels of viral genome-positive cells were observed in the spleens of marker rescue virus- and M2 mutant virus-infected mice, and these cells were exclusively sIgD - B cells. Taken together, these data convincingly demonstrate a role for the M2 gene product in reactivation from splenic B cells and also suggest that disruption of the M2 gene leads to dose- and route-specific defects in the efficient establishment of splenic B-cell latency.