JVI Accepts, published online ahead of print on 3 June 2009

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Google Scholar Articles by Marcus, P. I. Articles by Sekellick, M. J. PubMed PubMed Citation Articles by Marcus, P. I. Articles by Sekellick, M. J.

 Previous Article  |  Next Article 

J. Virol. doi:10.1128/JVI.02680-08
Copyright (c) 2009, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved.

Dynamics of Biologically Active Subpopulations of Influenza Virus: Plaque-Forming, Noninfectious Cell-Killing, and Defective-Interfering Particles

Philip I. Marcus^*, John M. Ngunjiri, and Margaret J. Sekellick

Department of Molecular and Cell Biology, and Center of Excellence for Vaccine Research, University of Connecticut, Storrs, Connecticut

^* To whom correspondence should be addressed. Email: philip.marcus{at}uconn.edu.

The dynamic changes in the temporal appearance and quantity of a new class of influenza virus, noninfectious cell-killing particles (niCKP), were compared to defective-interfering particles (DIP). After a single high multiplicity passage in MDCK cells of an egg-derived stock that lacked detectable niCKP or DIP, both classes of particles appeared in large numbers (> 5 x 10⁸/ml) and the PFP titer dropped some 60-fold. After two additional serial high multiplicity passages the DIP remained relatively constant, the DIP:niCKP ratio reached 10:1, and the PFP had declined by about 10,000-fold. Together, the niCKP and DIP subpopulations constituted 20% of the total hemagglutinating particle (HAP) population in which these noninfectious biologically active particles (niBAP) were subsumed. DIP neither killed cells, nor interfered with the cell-killing (apoptosis-inducing) activity of niCKP or PFP (infectious CKP), even though they blocked the replication of PFP. Relative to the UV-target of 13,600 nts for inactivation of PFP, the UV target for niCKP was 2,400 nts, consistent with one of the polymerase subunit genes, and that for DIP was 350 nts, consistent with the small DI-RNA responsible for DIP-mediated interference. Thus, niCKP and DIP are viewed as distinct particles with a propensity to form during infection at high multiplicities. These conditions are postulated to cause aberrations in the temporally regulated replication of virus and its packaging, leading to the production of niBAP. DIP have been implicated in the virulence of influenza, but the role of niCKP is yet unknown.