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.

Effect of physical form of the therapeutic diet on the behaviour of crossbred calves experimentally infected with foot-and-mouth disease virus.

The oral lesions associated with foot-and-mouth disease (FMD) negatively affect animal behavior, which can adversely impact animal production and welfare. Physical form of a therapeutic diet (TD) can improve the feed intake and wellbeing during the acute phase of FMD. Accordingly, we tested the effect of two physical forms of a previously developed TD on the behavior of calves experimentally infected with FMD virus (FMDV). Crossbred Holstein Friesian male calves of 10-12 months (n = 12) were experimentally infected with a virulent strain of FMDV and were offered a TD enriched with 19% CP and 2.9 Mcal ME/kg for 11 days post-FMDV infection. One group received the TD in mash form (TDM) while the other (n = 6/group) received it in cooked form (TDC). A group of four calves served as uninfected control and were fed TDM. The time spent by the calves on certain behaviours was recorded in a pre-set form from 06:00-18:00 h for 10 days from day 2-11 post-FMDV infection. The data was divided into two sessions. Session 1 (06:00-13:00 h) represented after the offering of TD, while session 2 (13:01-18:00 h) represented the data after offering green fodder. Based on exploratory data analysis, data recorded from day 2-7 post-FMDV infection was included in the final analysis. Linear mixed model was used by fitting treatment, day and their interaction as fixed effects while calf as random effect. Orthogonal contrast was applied by comparing the infected TDM with other two groups. The results revealed that the cooked form of TD improved the ingestion time, resting time, sleeping time and licking time from day 2-7 post-FMDV infection as compared with the infected TDM group. Ingestive behaviour was better in the infected TDC than that of TDM group (p < 0.01). The sleeping time was significantly high in the infected groups as compared to the uninfected TDM group (p < 0.01) till day 6 post-FMDV infection. Daily activities such as licking, standing and resting differed significantly between the infected TDM and TDC groups in session 1, but not in session 2. Urination and defecation did not differ significantly between the infected TDM and TDC groups. It was concluded that cooked form of TD remediated the effects of infection with FMDV as evidenced by improvement in the behaviour of the calves.