Modulating mouse innate immunity to RNA viruses by expressing the Bos taurus Mx system

Abstract

Mx proteins are interferon-induced members of the dynamin superfamily of large guanosine triphosphatases. These proteins have attracted much attention because some display antiviral activity against pathogenic RNA viruses, such as members of the orthomyxoviridae, bunyaviridae, and rhabdoviridae families. Among the diverse mammalian Mx proteins examined so far, we have recently demonstrated in vitro that the Bos taurus isoform 1 (boMx1) is endowed with exceptional anti-rabies-virus activity. This finding has prompted us to seek an appropriate in vivo model for confirming and evaluating gene therapy strategies. Using a BAC transgene, we have generated transgenic mouse lines expressing the antiviral boMx1 protein and boMx2 proteins under the control of their natural promoter and short- and long-range regulatory elements. Expressed boMx1 and boMx2 are correctly assembled, as deduced from mRNA sequencing and western blotting. Poly-I/C-subordinated expression of boMx1 was detected in various organs by immunohistochemistry, and transgenic lines were readily classified as high- or low-expression lines on the basis of tissue boMx1 concentrations measured by ELISA. Poly-I/C-induced Madin-Darby bovine kidney cells, bovine turbinate cells, and cultured cells from high-expression line of transgenic mice were found to contain about the same concentration of boMx1, suggesting that this protein is produced at near-physiological levels. Furthermore, insertion of the bovine Mx system rendered transgenic mice resistant to vesicular-stomatitis-virus-associated morbidity and mortality, and embryonic fibroblasts derived from high-expression transgenic mice were far less permissive to the virus. These results demonstrate that the Bos taurus Mx system is a powerful anti-VSV agent in vivo and suggest that the transgenic mouse lines generated here constitute a good model for studying in vivo the various antiviral functions-known and yet to be discovered-exerted by bovine Mx proteins, with priority emphasis on the antirabic function of boMx1.

Interferon Response and Viral Evasion by Members of the Family Rhabdoviridae

“…The human MxA protein was seen to inhibit both viral mRNA and protein levels following infection with VSV for 5 hours [ 98 ]. Furthermore, transgenic mice that express high levels of bovine Mx1 are resistant to a lethal challenge of VSV [ 99 ].…”

Bovine Mx1 enables resistance against foot-and-mouth disease virus in naturally susceptible cells by inhibiting the replication of viral RNA

“…Th e Mx proteins have anti-viral activity against RNA viruses such as the infl uenza virus, the Th ogoto virus, and coxsakievirus (Dotzauer and Kraemer, 2012;Matzinger et al, 2013;Patzina et al, 2014), and DNA viruses such as the hepatitis B virus and the African swine fever virus (Netherton et al, 2009;Li et al, 2012). Th e bovine Mx1 has also antiviral activity against the vesicular stomatitis virus, human rabies virus and murine respiratory syncytial virus (Baise et al, 2004;Leroy et al, 2006;Garigliany et al, 2009;Dermine and Desmecht, 2012). Although overexpression of bovine Mx1 protein inhibited replication of FMDV in BHK-21 cells (Cai et al, 2013), its function needs to be further confi rmed in naturally susceptible bovine cells from cattle, i.e.…”