Objective: To investigate the involvement of Ca2+ in dengue virus (DENV)-infected human umbilical vein endothelial cells (HUVECs) and the disruption of endothelial integrity. Methods: HUVECs were infected with DENV-2 in the presence of intracellular Ca2+ or endoplasmic reticulum Ca2+ chelators. Virus infectivity was measured by focus-forming assay and quantitative RT-PCR. Intracellular Ca2+ was measured using Fluo-4-AM dye. VE-cadherin and focal adhesion kinase (FAK) expressions were investigated by immunofluorescence and immunoblotting assays, respectively. Results: DENV infection increased intracellular cytosolic Ca2+ levels and caused disassembly of the adherens junction protein, VEcadherin as evidenced by decreased VE-cadherin expression at the periphery of DENV-2 infected HUVECs. Depletion of intracellular Ca2+ stores, particularly those of the endoplasmic reticulum Ca2+, significantly decreased DENV yield in HUVECs. Decreased virus yield following the depletion of intracellular Ca2+ was caused by the inhibition of viral entry into HUVECs and not the inhibition of viral binding or attachment. DENV-2 infection also resulted in Ca2+- dependent activation of FAK. Conclusions: Intracellular Ca2+ is required for the early phases of DENV infection in endothelial cells. Increased cytosolic Ca2+ levels in endothelial cells during DENV infection activated FAK, disrupted adherens junctions and compromised barrier integrity. Thus, Ca2+ plays an important role in DENV infection in endothelial cells.

The HACEK organisms consist of the non-influenzae Haemophilus sp., Aggregatibacter sp., Cardiobacterium sp., Eikenella corrodens and Kingella sp. are responsible for a sizable percentage of infective endocarditis cases worldwide with the mortality rate of 18%. Amongst them, Aggregatibacter actinomycetemcomitans is the most common pathogen strongly associated with infective endocarditis. A. actinomycetemcomitans forms part of the oral microbiota and is also the etiological agent of periodontitis. Here, we present a case of a 37-year-old man with underlying obstructive uropathy, that sought treatment for postural hypotension and symptomatic anaemia with fever. Later, he had developed decompensated congestive cardiac failure with aortic regurgitation. A cardiac echocardiogram revealed the presence of vegetation on the aortic valve. Blood culture grew A. actinomycetemcomitans, and he was treated with furosemide and ceftriaxone. A further dental examination showed the patient is having chronic periodontitis, which could be the possible source of A. actinomycetemcomitans causing infective endocarditis. The patient was then transferred to the National Heart Centre for the first time for further management after completion of 4 weeks of intravenous antibiotics. As the pathogen is fastidious, rapid and newer technology like MALDI-TOF mass spectrometry provides rapid and accurate identification for appropriate patient clinical management.