Karki Monu, Kumar Amit, Arya Sargam, Venkatesan Gnanavel
Division of Virology, ICAR- Indian Veterinary Research Institute, Mukteswar, Uttarakhand, India.
Division of Virology, ICAR- Indian Veterinary Research Institute, Mukteswar, Uttarakhand, India.
Virus Res. 2020 May;281:197908. doi: 10.1016/j.virusres.2020.197908. Epub 2020 Feb 29.
Orf, a poxviral skin infection of small ruminants is caused by orf virus (ORFV) of the genus Parapoxvirus of the Poxviridae family. Vascular endothelial growth factor (VEGF) is an important virulence factor that is responsible for proliferative lesions in parapoxviral infections. VEGF gene shows high intra- and inter-species variability. Two variants of VEGF have been described globally in ORFV, viz. NZ2- and NZ7-like. In the present study, ORFV isolates of different geographic regions of India were analysed on the basis of the VEGF gene. Indian ORFV isolates showed 95.7-100 % nucleotide (nt) and 78.4-99.3 % amino acid (aa) identity with each other, except ORFV-Assam/LK/14 and ORFV-Meghalaya/03 which shared 85.1-88.35 % and 79.1-81.8 % identity, at nt and aa levels, respectively with other Indian ORFV isolates. All Indian ORFVs under the study demonstrated 83.5-99.1 % nt and 80.5-97.9 % aa identity with NZ7-like VEGF as compared to 41.2-44.8 % nt and 30.7-38.4 % aa identity with NZ2-like VEGF on comparison with global ORFV strains. Phylogenetic analysis based on the VEGF gene showed two clusters of ORFV in which the Indian ORFVs clustered with NZ7-like VEGF from global ORFV strains, mostly from China. Despite the considerable variation, VEGF protein from Indian ORFV strains showed conserved VEGF homology domain with eight cysteine residues. Homology modeling of Indian ORFV strains predicted the presence of extended Loop 3 similar to NZ7-like VEGF. Therefore, the present study showed the circulation of ORFV strains with comparatively less variable NZ7-like VEGF in India which implicates its importance in the epidemiology of ORFV infections in the country.
羊痘是由痘病毒科副痘病毒属的羊痘病毒（ORFV）引起的小型反刍动物的一种痘病毒性皮肤感染。血管内皮生长因子（VEGF）是一种重要的毒力因子，在副痘病毒感染中导致增殖性病变。VEGF基因在种内和种间表现出高度变异性。在全球范围内，ORFV中已描述了两种VEGF变体，即NZ2样和NZ7样。在本研究中，基于VEGF基因对印度不同地理区域的ORFV分离株进行了分析。印度的ORFV分离株彼此之间显示出95.7% - 100%的核苷酸（nt）和78.4% - 99.3%的氨基酸（aa）同一性，但ORFV - 阿萨姆邦/LK/14和ORFV - 梅加拉亚邦/03分别与其他印度ORFV分离株在核苷酸和氨基酸水平上共享85.1% - 88.35%和79.1% - 81.8%的同一性。与全球ORFV菌株相比，本研究中的所有印度ORFV与NZ7样VEGF显示出83.5% - 99.1%的核苷酸和80.5% - 97.9%的氨基酸同一性，而与NZ2样VEGF的核苷酸和氨基酸同一性分别为41.2% - 44.8%和30.7% - 38.4%。基于VEGF基因的系统发育分析显示ORFV有两个聚类，其中印度的ORFV与全球ORFV菌株中的NZ7样VEGF聚类，大部分来自中国。尽管存在相当大的变异，但印度ORFV菌株的VEGF蛋白显示出具有八个半胱氨酸残基的保守VEGF同源结构域。印度ORFV菌株的同源建模预测存在与NZ7样VEGF相似的延伸环3。因此，本研究表明在印度存在具有相对较少可变的NZ7样VEGF的ORFV菌株的传播，这暗示了其在该国ORFV感染流行病学中的重要性。
