Аннотация:Plant viruses are a popular object for the development of new biotechnologies, including design of medical products (vaccines and adjuvants). Thereby, study of the structure, stability and other properties of plant viruses and their virus-like particles (VLPs) is a promising and upcoming research direction. In the present work Alternanthera mosaic virus (genus Potexvirus, family Alphaflexiviridae), the closest relative of the papaya mosaic virus (PMV), was studied. Recently we have shown that AltMV coat protein (CP) polymerizes in vitro into RNA-free VLPs that are identical in morphology with native AltMV virions. Here we demonstrated that AltMV virions and VLPs are stable in different conditions, including close to physiological (distilled water; 0.01 M Tris-HCl pH 7.5; 0.15 M NaCl; 0.01 M Tris-HCl pH 7.5, 0.15 M NaCl). The ability of AltMV CP to form stable VLPs at pH 7.5 and in the presence of 0.15 M NaCl significantly distinguishes it from the PMV CP, which forms stable VLPs in vitro only at pH 4.0. AltMV VLPs remained stable in mouse blood serum, which makes them a promising object for development of vaccines and biosafety adjuvants. For the first time the structure of AltMV virions and VLPs were compared by the CP trypsin-degradation assays designed in our lab earlier (Rodionova et al., 2003). AltMV virions were trypsin-resistant, whereas VLPs were partially hydrolyzed. According to these data, AltMV virions and VLPs are similar morphologically, but have a different structure of the helical protein capsid. We also modified the procedure for AltMV isolation and significantly increased the yield of the purified virus that is necessary for the practical application of VLPs and virions.
This work was funded by the Russian Science Foundation (Grant No 14-24-00007).