The In Vitro Association of Swine Influenza Virus with Metastrongylus Species

ABSTRACT It has been shown previously that the nonstructural protein NS1 of influenza virus is an alpha/beta interferon (IFN-α/β) antagonist, both in vitro and in experimental animal model systems. However, evidence of this function in a natural host has not yet been obtained. Here we investigated the role of the NS1 protein in the virulence of a swine influenza virus (SIV) isolate in pigs by using reverse genetics. The virulent wild-type A/Swine/Texas/4199-2/98 (TX/98) virus and various mutants encoding carboxy-truncated NS1 proteins were rescued. Growth properties of TX/98 viruses with mutated NS1, induction of IFN in tissue culture, and virulence-attenuation in pigs were analyzed and compared to those of the recombinant wild-type TX/98 virus. Our results indicate that deletions in the NS1 protein decrease the ability of the TX/98 virus to prevent IFN-α/β synthesis in pig cells. Moreover, all NS1 mutant viruses were attenuated in pigs, and this correlated with the amount of IFN-α/β induced in vitro. These data suggest that the NS1 protein of SIV is a virulence factor. Due to their attenuation, NS1-mutated swine influenza viruses might have a great potential as live attenuated vaccine candidates against SIV infections of pigs.

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Mitochondrial antiviral signaling adaptor mediated apoptosis in H3N2 swine influenza virus infection is inhibited by viral protein NS1 in vitro

Veterinary Immunology and Immunopathology ◽

10.1016/j.vetimm.2015.03.003 ◽

2015 ◽

Vol 165 (1-2) ◽

pp. 34-44 ◽

Cited By ~ 3

Author(s):

Jinqiu Zhang ◽

Jinfeng Miao ◽

Jibo Hou ◽

Chengping Lu

Keyword(s):

Influenza Virus ◽

Virus Infection ◽

Viral Protein ◽

Swine Influenza Virus ◽

Influenza Virus Infection ◽

Swine Influenza ◽

Antiviral Signaling ◽

Mitochondrial Antiviral Signaling

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A STUDY IN VITRO OF COMPONENTS IN THE TRANSMISSION CYCLE OF SWINE INFLUENZA VIRUS

Journal of Experimental Medicine ◽

10.1084/jem.114.6.1023 ◽

1961 ◽

Vol 114 (6) ◽

pp. 1023-1033 ◽

Cited By ~ 5

Author(s):

W. D. Peterson ◽

Fred M. Davenport ◽

Thomas Francis

Keyword(s):

Influenza Virus ◽

Infectious Virus ◽

Swine Influenza Virus ◽

Swine Influenza ◽

Influenza Virus A ◽

Transmission Cycle

Swine lungworm extracts and suspensions of swine lungworms contain receptor-like substances capable of adsorbing influenza virus, a result consonant with the hypothesis (5–8) that the lungworm may be involved in the swine influenza cycle. Yet no evidence for multiplication of virus or even persistence of infectious virus in lungworms at undimished titer was found. Clearly much more information is needed, and it is hoped that the present demonstration of the practicality of studying the components of the transmission cycle proposed by Shope, will provide important tools requisite for further investigation of this problem. Studies on the role of the earthworm in the transmission of swine influenza suggest that, at best, that role would be a passive one.

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AN INTESTINAL THREADWORM AS A RESERVOIR AND INTERMEDIATE HOST FOR SWINE INFLUENZA VIRUS

Journal of Experimental Medicine ◽

10.1084/jem.127.2.359 ◽

1968 ◽

Vol 127 (2) ◽

pp. 359-369 ◽

Cited By ~ 4

Author(s):

Emmett B. Shotts ◽

John W. Foster ◽

Max Brugh ◽

Helen E. Jordan ◽

James L. McQueen

Keyword(s):

Influenza Virus ◽

Life Cycle ◽

Swine Influenza Virus ◽

Swine Influenza ◽

Laboratory Model ◽

Intranasal Route ◽

Complete Life Cycle ◽

Vertebrate Hosts ◽

Mouse Lungs

A laboratory model exemplifying Shope's concept of virus carriage by helminths was developed using Strongyloides ratti (Sandground, 1925), swine influenza virus, and caesarean-originated, barrier-sustained (COBS) mice and rats. It was shown that S. ratti can act as a carrier of swine influenza virus and infect mice, despite the fact that the nematode has undergone a complete life cycle after exposure to virus in infected rats. COBS rats were inoculated with the virus via the intranasal route and subsequently infected with S. ratti. The larvae and eggs found in the feces collected from these rats were allowed to develop in vitro. These second generation filariform larvae were then inoculated subcutaneously into COBS mice. At necropsy, 5–8 days postinoculation, swine influenza virus was isolated from 15% of the mouse lungs. In control studies, swine influenza virus was not isolated from the feces of the COBS rats which served as a source of both unexposed and exposed S. ratti. Swine influenza virus was recovered in vitro from S. ratti homogenates. It is suggested that this laboratory model be used to study more closely the various aspects of the ecology of virus-helminth relationships in vertebrate hosts.

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