Type I interferon gene therapy protects against cytomegalovirus‐induced myocarditis

Abstract

SUMMARYType I interferons (IFNs) are produced early in response to viral infection and modulate adaptive immunity. Previously we demonstrated localized protection against murine cytomegalovirus (MCMV) infection in IFN DNA-inoculated mice. Here we examine the effect of seven IFN subtypes (IFNA1, A2, A4, A5, A6, A9 and B), administered by DNA inoculation, on systemic MCMV infection and myocarditis. IFN transgene expression altered the pathogenesis of MCMV infection with regard to virus titre and myocarditis. IFNA6 treatment reduced MCMV replication whilst IFNA5 and A2 enhanced virus replication. IFNA6, A9, and B treatment inhibited acute myocarditis. A T helper type 1-like, antibody and cytokine, response correlated with decreased virus titre and myocarditis. In addition, IFNA6 was able to reduce chronic cardiac inflammation. This research into the effectiveness of seven type I IFNs, using DNA gene therapy, highlights the need for correct subtype usage in the treatment of disease. We demonstrate effective subtypes for treatment in both the acute and chronic phases of MCMV infection and the resultant development of myocarditis.

Coimmunisation with type I IFN genes enhances protective immunity against cytomegalovirus and myocarditis in gB DNA-vaccinated mice

“…Indeed, we have recently shown manipulation of anti-MCMV immune responses with use of type I IFN DNA expression in vivo. 24 Type I IFN has been shown to affect B cells, enhancing IgM, IgG2a and IgA antibody production. 27 The envelope glycoproteins of CMV are important antigenic targets for the immune response.…”

“…Our previous studies showed no effect of either IFN-A9 or IFN-B DNA alone on virus replication in this organ. 24 Thus our DNA vaccine approach had limited effect at inhibiting both viral tropism and MCMV replication in this organ. Since it is known that CD4 + T cell responses control CMV replication in the salivary glands, the DNA vaccination approach may not be favourable for protection in this organ.…”

“…The three type I IFN genes investigated, IFN-A6, -A9 and -B were chosen due to previous findings of their strong capacity to either reduce MCMV titres or MCMV-induced myocarditis in the murine model. 24 The IFN genes were cloned within 20 nucleotides of the start and stop codons for increased stability and expression of transcripts (Figure 1a). RNA transcripts produced by transfected COS-7 cells were confirmed to be similar in expression levels for the transfected gene by Northern analysis (Figure 1b).…”

“…Mice inoculated with either IFN-A9 or IFN-B alone did not show significantly reduced virus titres in the spleen or liver. 24 Next we examined the level of viral replication in the salivary glands at day 7 p.i., the initial phase of persistent MCMV infection in this tissue. Neither the gB vaccine alone nor any combination with the co-injected IFN subtypes was capable of reducing viral titres in the salivary glands ( Figure 2c).…”

“…To compare the specific roles of IFN subtypes as costimulatory cytokines for immune induction in a CMV murine model, we constructed plasmid DNAs expressing IFN-alpha 6, IFNalpha 9 and IFN-beta, 24 coimmunised mice with the IFN plasmid and the gB DNA plasmid vaccine, and then analysed immunomodulatory effects in vivo. We demonstrate that DNA encoding IFN-gene cassettes when coinoculated with the gB DNA vaccine provides better protective immunity against CMV infection in mice than gB DNA alone.…”