Reconstituted coronavirus TGEV virosomes lose the virus ability to induce porcine interferon-alpha production.
The transmissible gastroenteritis virus (TGEV) is a coronavirus which induces a strong interferon-alpha (IFN-alpha) production in vivo and in vitro. Previous studies have shown that the TGEV external protein M plays a major role in IFN-alpha induction by a non-infectious virus, whereas protein S is not involved. The present study extended these results by showing that monoclonal antibodies (MAbs) directed at the external viral protein sM could not block IFN-alpha induction, which argues against a direct role for this protein. In the same type of blocking experiment, MAbs to the TGEV receptor aminopeptidase N did not inhibit IFN-alpha induction, which strongly indicates that viral replication or entry through the receptor is not needed for TGEV induction of IFN-alpha in leukocytes. In an attempt to isolate functional envelope proteins, TGEV virions were detergent-solubilized and reconstituted in virosomes. Although BIAcore antigenic analysis revealed that the three external viral proteins were present on the virosomes, these proteins were unable to induce IFN-alpha in porcine leukocytes, and seemed to compete with the native virus for IFN-alpha induction. These data indicated that IFN-alpha inducing interactions between TGEV external proteins and leukocytes required a complex native envelope protein structure which has been lost in the virosomes.
Riffault
S
S
Virologie et immunologie moléculaires, Inra, Jouy-en-Josas, France. riffault@biotec.jouy.inra.fr
Grosclaude
J
J
Vayssier
M
M
Laude
H
H
Charley
B
B
D000818:Animals; D000911:Antibodies, Monoclonal; D000918:Antibody Specificity; D004797:Enzyme-Linked Immunosorbent Assay; D016898:Interferon-alpha / Q000096:biosynthesis*; D008214:Lymphocytes / Q000276:immunology* / Q000821:virology; D011991:Receptors, Virus / Q000276:immunology / Q000502:physiology; D013552:Swine; D005760:Transmissible gastroenteritis virus / Q000276:immunology / Q000502:physiology*; D014764:Viral Proteins / Q000276:immunology*
D000911:Antibodies, Monoclonal; D016898:Interferon-alpha; D011991:Receptors, Virus; D014764:Viral Proteins