Influenza Virus Reassortment Occurs with High Frequency in the Absence of Segment Mismatch

PLoS Pathogens

Zachary Ende¹  Nicolle Marshall¹  Anice C. Lowen²  Lalita Priyamvada³  John Steel³ 

[1] Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia, United States of America;Emory Vaccine Center at Yerkes National Primate Research Center, Atlanta, Georgia, United States of America;Microbiology and Molecular Genetics Graduate Program, Emory University, Atlanta, Georgia, United States of America

关键词: Co-infections;    Guinea pigs;    Influenza viruses;    Cell cultures;    Influenza A virus;    Viral replication;    Flow cytometry;    Viral genomics;   

DOI  :  10.1371/journal.ppat.1003421

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

Reassortment is fundamental to the evolution of influenza viruses and plays a key role in the generation of epidemiologically significant strains. Previous studies indicate that reassortment is restricted by segment mismatch, arising from functional incompatibilities among components of two viruses. Additional factors that dictate the efficiency of reassortment remain poorly characterized. Thus, it is unclear what conditions are favorable for reassortment and therefore under what circumstances novel influenza A viruses might arise in nature. Herein, we describe a system for studying reassortment in the absence of segment mismatch and exploit this system to determine the baseline efficiency of reassortment and the effects of infection dose and timing. Silent mutations were introduced into A/Panama/2007/99 virus such that high-resolution melt analysis could be used to differentiate all eight segments of the wild-type and the silently mutated variant virus. The use of phenotypically identical parent viruses ensured that all progeny were equally fit, allowing reassortment to be measured without selection bias. Using this system, we found that reassortment occurred efficiently (88.4%) following high multiplicity infection, suggesting the process is not appreciably limited by intracellular compartmentalization. That co-infection is the major determinant of reassortment efficiency in the absence of segment mismatch was confirmed with the observation that the proportion of viruses with reassortant genotypes increased exponentially with the proportion of cells co-infected. The number of reassortants shed from co-infected guinea pigs was likewise dependent on dose. With 106 PFU inocula, 46%–86% of viruses isolated from guinea pigs were reassortants. The introduction of a delay between infections also had a strong impact on reassortment and allowed definition of time windows during which super-infection led to reassortment in culture and in vivo. Overall, our results indicate that reassortment between two like influenza viruses is efficient but also strongly dependent on dose and timing of the infections.

【 授权许可】

CC BY