IFN function is critical for recovery from most primary viral infections, including poxvirus infection. In contrast, very little is known about the requirement for IFN function in mediating recovery from a secondary virus infection. We have used ectromelia virus (ECTV), an orthopoxvirus very closely related to variola virus, to investigate the importance of IFN function in recovery from a secondary infection. Variola virus, the causative agent of smallpox in humans, and ECTV, which causes mousepox in mice, both encode receptor homologs that are thought to interfere with host IFN function. Using a prime–challenge regime, in which avirulent ECTV is used to prime mice deficient in type I
II IFN function or IFN regulatory factor 1 (IRF-1) and then challenging the mice with a virulent strain, we show that IFN function is redundant for virus clearance during a secondary ECTV infection. A neutralizing Ab response is generated in a secondary infection, even in the absence of IFN function, although when present, IFN strongly influences the neutralizing titer and subtype of IgG that is produced. Importantly, the depletion of CD8
T lymphocytes during a secondary challenge in IFN-deficient mice does not affect their capacity to clear ECTV, indicating that Ab is critical for the control of a secondary infection.

Item Type:	Refereed Article
Keywords:	Poxvirus; Interferon responses; secondary viral infection viral infection
Research Division:	Biomedical and Clinical Sciences
Research Group:	Medical microbiology
Research Field:	Medical virology
Objective Division:	Health
Objective Group:	Clinical health
Objective Field:	Prevention of human diseases and conditions
UTAS Author:	Karupiah, G (Associate Professor Guna Karupiah)
ID Code:	142826
Year Published:	2005
Web of Science® Times Cited:	42
Deposited By:	Medicine
Deposited On:	2021-02-12
Last Modified:	2021-03-31
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