The M/GP5 Glycoprotein Complex of Porcine Reproductive and Respiratory Syndrome Virus Binds the Sialoadhesin Receptor in a Sialic Acid-Dependent Manner

The porcine reproductive and respiratory syndrome virus (PRRSV) is a major threat to swine health worldwide and is considered the most significant viral disease in the swine industry today. In past years, studies on the entry of the virus into its host cell have led to the identification of a number of essential virus receptors and entry mediators. However, viral counterparts for these molecules have remained elusive and this has made rational development of new generation vaccines impossible. The main objective of this study was to identify the viral counterparts for sialoadhesin, a crucial PRRSV receptor on macrophages. For this purpose, a soluble form of sialoadhesin was constructed and validated. The soluble sialoadhesin could bind PRRSV in a sialic acid-dependent manner and could neutralize PRRSV infection of macrophages, thereby confirming the role of sialoadhesin as an essential PRRSV receptor on macrophages. Although sialic acids are present on the GP3, GP4 and GP5 envelope glycoproteins, only the M/GP5 glycoprotein complex of PRRSV was identified as a ligand for sialoadhesin. The interaction was found to be dependent on the sialic acid binding capacity of sialoadhesin and on the presence of sialic acids on GP5. These findings not only contribute to a better understanding of PRRSV biology, but the knowledge and tools generated in this study also hold the key to the development of a new generation of PRRSV vaccines

Selected Abstracts of the TEEPGI 2013 Workshop (1st to 3rd March 2013)

Background Paravalvular or paraprosthetic leak (PVL) is a complication associated with the surgical/transcatheter implantation of a prosthetic heart valve, more commonly a mechanical than a bioprosthetic valve. Transthoracic echocardiography (TTE) is the most important diagnostic modality for prosthetic valve function/dysfunction. However, TTE often cannot differentiate the PVL from prosthetic regurgitation. Transesophageal echocardiography (TEE) is the modality of choice which is also able to detect small, nonsignificant jets. Case Report We present a case of 78-year-old male who had undergone mitral valve replacement with Epic St. Jude tissue valve 3 years back and now presented to our hospital with NYHA class III dyspnea since few months prior to admission. It was associated with cough with mucoid expectoration along with orthopnea. TTE revealed moderate PAH with increased gradient across bioprosthetic mitral valve with suspicion of peravalvular leak (Fig. 1). Three-dimensional (3D) volume rendering image analysis after cropping suggested oval perivalvular area of leakage which was confirmed with the help of 3D color rendering (Fig. 2). It showed early separation of perivalvular leak from paravalvular area. Discussion The majority of PVL are crescent, oval or roundish-shaped and their track can be parallel, perpendicular or serpiginous. Incidence of PVL, including small nonsignificant jets, is estimated to be as high as 20%.1 TEE is more useful than TTE in evaluating the shape of paravalvular defect. It may also help in assessing eccentric jets and differentiating between single and multiple jets. Major progress in TEE in the area of PVL imaging has been 3D reconstruction.2 A semiquantitative assessment of the size of PVL may be made by measurement of the ratio of total sewing ring circumference to the length of suture dehiscence (&gt;10%: Mild, 10-20%: Moderate, &gt;20%: Severe, &gt;40%: Instability of the prosthetic valve).3 Conclusion The TEE, especially if 3D volume rendering is used along with, provides a systematic method to accurately localize native and prosthetic mitral valve regurgitant lesions. Also, paravalvular leaks may be more easily delineated and quantified using 3D echo. Due to accurate localization of the defects, this modality helps to improve the preoperative assessment and decisions about patients with significant mitral regurgitation. </jats:sec