Experimental SSM-CVB3 infection in macaques

High risk of renal dysfunction in patients with fulminant type 1 diabetes

AIMS/INTRODUCTION

To compare the incidence rate of renal dysfunction between patients with fulminant type 1 diabetes and those with acute-onset type 1 diabetes.

MATERIALS AND METHODS

The present retrospective cohort study included patients with fulminant type 1 diabetes and acute-onset type 1 diabetes diagnosed during April 1993 to March 2016 at a national center in Japan. Glycated hemoglobin levels, incidence rates of renal dysfunction defined as an estimated glomerular filtration rate of <60 mL/min/1.73 m² and microalbuminuria were examined.

RESULTS

In total, 115 patients with type 1 diabetes (10 with fulminant type 1 diabetes and 105 with acute-onset type 1 diabetes) were included. The median glycated hemoglobin levels were significantly lower in patients with fulminant type 1 diabetes than in those with acute-onset type 1 diabetes 0, 3, 6 and 9 years after diabetes onset (6.5 vs 12.7%, 6.5 vs 7.9%, 6.7 vs 8.2%, 7.5 vs 8.5%, respectively). Kaplan-Meier analysis showed a significantly higher incidence rate of renal dysfunction in patients with fulminant type 1 diabetes than in those with acute-onset type 1 diabetes (hazard ratio 1.72, 95% confidence interval 1.01-2.97, P = 0.037). The incidence rate of microalbuminuria did not significantly differ between the groups (hazard ratio 0.97, 95% confidence interval 0.34-2.77, P = 0.95). Sensitivity analysis using age- and sex-matched patients with fulminant type 1 diabetes and acute-onset type 1 diabetes yielded similar results.

CONCLUSIONS

The risk of developing renal dysfunction is higher in patients with fulminant type 1 diabetes than in those with acute-onset type 1 diabetes, despite better glycemic control.

Interspecies differences in virus uptake versus cardiac function of the coxsackievirus and adenovirus receptor

The coxsackievirus and adenovirus receptor (CAR) is a cell contact protein with an important role in virus uptake. Its extracellular immunoglobulin domains mediate the binding to coxsackievirus and adenovirus as well as homophilic and heterophilic interactions between cells. The cytoplasmic tail links CAR to the cytoskeleton and intracellular signaling cascades. In the heart, CAR is crucial for embryonic development, electrophysiology, and coxsackievirus B infection. Noncardiac functions are less well understood, in part due to the lack of suitable animal models. Here, we generated a transgenic mouse that rescued the otherwise embryonic-lethal CAR knockout (KO) phenotype by expressing chicken CAR exclusively in the heart. Using this rescue model, we addressed interspecies differences in coxsackievirus uptake and noncardiac functions of CAR. Survival of the noncardiac CAR KO (ncKO) mouse indicates an essential role for CAR in the developing heart but not in other tissues. In adult animals, cardiac activity was normal, suggesting that chicken CAR can replace the physiological functions of mouse CAR in the cardiomyocyte. However, chicken CAR did not mediate virus entry in vivo, so that hearts expressing chicken instead of mouse CAR were protected from infection and myocarditis. Comparison of sequence homology and modeling of the D1 domain indicate differences between mammalian and chicken CAR that relate to the sites important for virus binding but not those involved in homodimerization. Thus, CAR-directed anticoxsackievirus therapy with only minor adverse effects in noncardiac tissue could be further improved by selectively targeting the virus-host interaction while maintaining cardiac function.

IMPORTANCE

Coxsackievirus B3 (CVB3) is one of the most common human pathogens causing myocarditis. Its receptor, the coxsackievirus and adenovirus receptor (CAR), not only mediates virus uptake but also relates to cytoskeletal organization and intracellular signaling. Animals without CAR die prenatally with major cardiac malformations. In the adult heart, CAR is important for virus entry and electrical conduction, but its nonmuscle functions are largely unknown. Here, we show that chicken CAR expression exclusively in the heart can rescue the otherwise embryonic-lethal CAR knockout phenotype but does not support CVB3 infection of adult cardiomyocytes. Our findings have implications for the evolution of virus-host versus physiological interactions involving CAR and could help to improve future coxsackievirus-directed therapies inhibiting virus replication while maintaining CAR's cellular functions.

Complete genome sequence of a coxsackievirus B3 isolated from a Sichuan snub-nosed monkey

Coxsackievirus B3 (CVB3) is an enterovirus in the family Picornaviridae that is significant to human health, being associated with myocarditis, aseptic meningitis, and pancreatitis, among other conditions. In addition to humans, Sichuan snub-nosed monkeys can be infected and killed by CVB3. Here, we report the first complete genome sequence of a novel coxsackievirus B3 strain, SSM-CVB3, which was isolated from a deceased Sichuan snub-nosed monkey with severe myocarditis. Our findings may aid in understanding the evolutionary characteristics and molecular pathogenesis of this virus.

Viral kinetics are associated with changes in cytokines and chemokines in serum and target organs of SSM-CVB3-infected macaques

OBJECTIVE

To determine the relationship between viral kinetics and the expression patterns for different cytokines and chemokines in the serum and organs of coxsackievirus B3 (SSM-CVB3)-infected macaques over the course of infection.

METHODS

SSM-CVB3 levels in serum and organs were measured using the Spearman-Karber 50% tissue culture infectious dose (TCID(50)) method. Cytokine and chemokine levels in the serum and organs were measured by indirect-ELISA.

RESULTS

Low viral titers were detected in the serum samples on the first day post-inoculation (p.i.) and peaked at 6 to 10 days p.i. in the serum samples from five macaques. Serum levels of IL-1β, IL-2, IL-6, IL-12p40, IL-17α, IFN-γ, TNF-α, MCP-1 and MIP-1β were detected each day and, similar to the viral titers, peaked at 6 to 10 days. IL-10 was only detected on days 10 to 14 p.i. Additionally, higher viral titers and relative viral mRNA levels were associated with higher cytokine and chemokine levels in selected tissues from infected macaques including heart, liver, spleen, lung, kidney and brain.

CONCLUSION

The results indicate that patterns of cytokine and chemokine response are associated with viral kinetics in the serum and target organs of SSM-CVB3-infected macaques, suggesting that the changes in cytokines and chemokines could help further our understanding of the progress of CVB3 infections in clinical settings.