Experimental infection of foot and mouth disease virus (FMDV) upregulates the expression of Coxsackie and adenovirus receptor (CAR) in the myocardium of suckling mice

The relative overexpression of Coxsackie and adenoviral receptor (CAR) predisposes children to viral myocarditis. As the foot and mouth disease virus (FMDV) causes fatal myocarditis in calves, lambs, and piglets and belongs to the same family as the Coxsackie virus, we investigated the role of CAR in FMDV induced myocarditis in the suckling mice model. Swiss albino suckling mice of 5 days (n = 24) were divided into two equal groups. One group was inoculated with suckling mice adapted FMDV serotype O at 10 LD50, while the other group served as uninfected control. In addition, adult mice (n = 12) served as the control for age related CAR expression and lack of pathogenicity to FMDV. The establishment of myocarditis was confirmed by histopathological changes typical of myocarditis along with immunolocalization of FMDV antigens in the heart of suckling mice. The FMDV inoculated suckling mice group showed a significant upregulation of CAR transcripts by 2.5 folds, overexpression of CAR protein by densitometric analysis of immunoblots, and intense immunolocalization of CAR in the sarcolemma and intercalated discs of cardiomyocytes as compared to the uninfected suckling mice group and adult mice. It was concluded that FMDV infection induced overexpression of CAR in the myocardium of suckling mice.

Induction of antiviral and cell mediated immune responses significantly reduce viral load in an acute foot-and-mouth disease virus infection in cattle

Foot-and-mouth disease virus (FMDV) causes a severe infection in ruminant animals. Here we present an in-depth transcriptional analysis of soft-palate tissue from cattle experimentally infected with FMDV. The differentially expressed genes from two Indian cattle (Bos indicus) breeds (Malnad Gidda and Hallikar) and Holstein Friesian (HF) crossbred calves, highlighted the activation of metabolic processes, mitochondrial functions and significant enrichment of innate antiviral immune response pathways in the indigenous calves. The results of RT-qPCR based validation of 12 genes was in alignment with the transcriptome data. The indigenous calves showing lesser virus load, elicited early neutralizing antibodies and IFN-γ immune responses. This study revealed that induction of potent innate antiviral response and cell mediated immunity in indigenous cattle, especially Malnad Gidda, significantly restricted FMDV replication during acute infection. These data highlighting the molecular processes associated with host-pathogen interactions, could aid in the conception of novel strategies to prevent and control FMDV infection in cattle.

Efficient inhibition of foot-and-mouth disease virus replication in vitro by artificial microRNA targeting 3D polymerase

Foot-and-mouth disease (FMD) is a devastating acute viral disease of livestock with cloven hooves. Among various therapeutic control measures, RNA interference (RNAi) is one of the methods being explored to inhibit FMD virus replication and spread. The RNAi is achieved by short hairpin RNAs or artificial microRNAs (amiRNAs). Utility of amiRNAs as antiviral, targeting conserved regions of the viral genome is gaining importance. However, delivery of miRNA in vivo is still a challenge. In this study, the efficacy of amiRNAs in preventing FMD virus replication in a permissive cell culture system was investigated, by generating stable cell lines expressing amiRNAs targeting three functional regions of the FMD virus (FMDV) genome (IRES, 3B3 and 3D). The results showed that amiRNA targeting 3D polymerase is relatively more efficient. However, expression of multiple microRNAs targeting the three regions did not exhibit additive effect. The data suggest that 3D specific miRNA is a potential valid strategy in developing novel antiviral measures against FMDV infection. Keywords: artificial microRNA; foot-and-mouth disease virus; virus inhibition.