Diab Emad, Bazid Abdel-Hamid I, Fawzy Mohamed, El-Ashmawy Wagdy R, Fayed Adel A, El-Sayed Magdy M
Department of Internal Medicine and Infectious Diseases, Faculty of Veterinary Medicine, Cairo University, Cairo 12211, Egypt.
Department of Virology, Faculty of Veterinary Medicine, University of Sadat City, Menoufia 32958, Egypt.
Vet World. 2019;12(2):190-197. doi: 10.14202/vetworld.2019.190-197. Epub 2019 Feb 5.
Foot-and-mouth disease virus (FMDV) serotypes A, O and South African Territories (SAT2) are endemic in Egypt; each is presented by a number of partially related topotypes and lineages, depending on their geographical origin. Continuous mutations and the emergence of new topotypes that lead to occasional vaccination failures were frequently recorded, so this study aimed to genetically characterize the circulating FMD virus strains in Egypt during 2013 and 2014 outbreaks, focusing on amino acids variations in VP1 region.
A total of 51 oral tissue samples were collected from cattle and buffaloes in 13 farms, and 38 individual cases showed clinical signs suspected to be FMD in six Egyptian Governorates (Cairo, Giza, Qaliubia, Fayoum, Sharquia, and Assiut). FMDV in collected samples was characterized by reverse transcription-polymerase chain reaction (RT-PCR) amplification of full VP1 region, sequencing, and phylogenetic analysis.
Out of 51 samples, 44 (86.27%) were positive by RT-PCR using universal primers. Serotype O was predominant and detected in 31 samples (70.45%), serotype A was detected in 9 samples (20.45%), and then serotype SAT2 was identified in 4 samples (9.10%). Sequencing and phylogenetic analysis of VP1 demonstrated clustering of serotype O, A, and SAT2 in EA-3 topotype, ASIA topotype, and topotype VII, respectively. Serotype O is closely related to O/SUD/8/2008 with 94.6% identity but showed 14.6% differences from vaccine strain (O/PanAsia-2) of ME-SA topotype. Furthermore, Serotype A and SAT2 were closely related to recent circulating Egyptian isolates and vaccine strains type A/EGY/1/2012 (Asia topotype, lineage Iran-05) with identity 96.4% and vaccine strain of SAT2/EGY/A/2012 (topotype VII, lineage SAT2/VII/ALX-12) with identity 95.3%, respectively.
The present study recommended further studies of serotype O to determine the immunogenic relationship between the vaccine strain and the new strains to attain maximum protection against circulating viruses.
口蹄疫病毒（FMDV）的A、O和南非地区（SAT2）血清型在埃及呈地方流行；根据其地理来源，每种血清型又由许多部分相关的拓扑型和谱系代表。经常记录到持续的突变以及导致偶尔疫苗接种失败的新拓扑型的出现，因此本研究旨在对2013年和2014年疫情期间埃及流行的口蹄疫病毒株进行基因特征分析，重点关注VP1区域的氨基酸变异。
从13个农场的牛和水牛身上共采集了51份口腔组织样本，在埃及的六个省（开罗、吉萨、盖勒尤卜、法尤姆、谢赫村和艾斯尤特），38例个体病例表现出疑似口蹄疫的临床症状。通过对完整VP1区域进行逆转录聚合酶链反应（RT-PCR）扩增、测序和系统发育分析，对采集样本中的口蹄疫病毒进行特征分析。
在51份样本中，使用通用引物进行RT-PCR检测，44份（86.27%）呈阳性。O型血清型占主导，在31份样本（70.45%）中检测到，A型血清型在9份样本（20.45%）中检测到，随后在4份样本（9.10%）中鉴定出SAT2型血清型。VP1的测序和系统发育分析表明，O型、A型和SAT2型分别在EA-3拓扑型、亚洲拓扑型和拓扑型VII中聚类。O型血清型与O/SUD/8/2008密切相关，同一性为94.6%，但与中东-南非拓扑型的疫苗株（O/PanAsia-2）有14.6%的差异。此外，A型和SAT2型血清型分别与埃及近期流行的分离株和疫苗株A/EGY/1/2012（亚洲拓扑型，伊朗-05谱系）同一性为96.4%以及SAT2/EGY/A/2012疫苗株（拓扑型VII，SAT2/VII/ALX-12谱系）同一性为95.3%密切相关。
本研究建议对口蹄疫O型血清型进行进一步研究，以确定疫苗株与新毒株之间的免疫原性关系，从而获得对流行病毒的最大保护。
