Khoshnood Siamak, Azimi Seyed Mahmoud, Kafi Zahra Ziafati, Najafi Hamideh, Langeroudi Arash Ghalyanchi
Department of Microbiology and Immunology, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran.
Foot and Mouth Disease Reference Laboratory, Agricultural Research, Education and Extension Organization (AREEO), Razi Vaccine and Serum Research Institute, Karaj, Iran.
Virus Genes. 2025 Aug;61(4):498-504. doi: 10.1007/s11262-025-02166-y. Epub 2025 Jun 13.
Foot-and-mouth disease (FMD) is a highly infectious viral infection that has a significant economic impact on livestock farming worldwide. The adaptability of a field isolate of FMDV virus for rapid isolation and production of a high antigen titer is one of the concerns of vaccine preparation, which can delay and endanger effective control programs. During a period between 2019 and 2020, a total of 63 oral epithelial samples were collected from vaccinated cattle. These samples were first analyzed and typed to identify the virus using ELISA method. Subsequently, the field virus was isolated using two continuous cell lines, BHK-21 and IB-IS2. Cytopathic effects (CPE) were observed under an inverted microscope, and then viral titration of isolated viruses was determined. Of 63 samples received from 2019 to 2020, 50 samples (79.36%) were reported positive by type-specific ELISA and typed as follows: 32 samples (64%) were type O, and 18 samples (36%) were type A. Of 50 positive samples, 38 samples (76%) were isolated in the IB-IS2 cell culture (26 samples type O, 12 samples type A) and 12 samples (34%) were isolated in the BHK-21 cell culture (9 samples type O, 3 samples type A) during three consecutive passages. The mean virus titration of isolated viruses was 10 TCID in the IB-IS2 cell line and 10 TCID in BHK-21 cell line. 26 samples that were initially isolated on the IB-IS2 cell line but not on the BHK-21 cell line were successfully isolated on the BHK-21 cell line after three consecutive passages of culture on the IB-IS2 cell line. In these samples, an average increase of about 10 in TCID50 was observed. Although both studied cell lines are suitable for the culture of Foot-and-mouth Disease virus, the IB-IS2 cell line is particularly suitable for the isolation of field viruses. While according to the virus titer (TCID50) produced in the BHK-21 cell line, this cell line is suitable for large-scale virus culture and appropriate for the production of inactivated vaccines.
口蹄疫（FMD）是一种极具传染性的病毒感染，对全球畜牧业有着重大经济影响。口蹄疫病毒（FMDV）野毒株快速分离及产生高抗原滴度的适应性是疫苗制备的关注点之一，这可能会延误并危及有效的防控计划。在2019年至2020年期间，共从接种疫苗的牛身上采集了63份口腔上皮样本。首先使用ELISA方法对这些样本进行分析和分型以鉴定病毒。随后，使用两种连续细胞系BHK - 21和IB - IS2分离野毒株。在倒置显微镜下观察细胞病变效应（CPE），然后测定分离病毒的病毒滴度。在2019年至2020年收到的63份样本中，50份样本（79.36%）经型特异性ELISA检测呈阳性，分型如下：32份样本（64%）为O型，18份样本（36%）为A型。在50份阳性样本中，38份样本（76%）在IB - IS2细胞培养物中分离出来（26份O型样本，12份A型样本），12份样本（34%）在BHK - 21细胞培养物中分离出来（9份O型样本，3份A型样本），经过连续三代传代培养。在IB - IS2细胞系中分离病毒的平均病毒滴度为10⁸ TCID₅₀，在BHK - 21细胞系中为10⁷ TCID₅₀。最初在IB - IS2细胞系上分离但未在BHK - 21细胞系上分离的26份样本，在IB - IS2细胞系上连续传代培养三代后成功在BHK - 21细胞系上分离出来。在这些样本中，观察到TCID₅₀平均增加约10⁵。虽然两种研究的细胞系都适合口蹄疫病毒的培养，但IB - IS2细胞系特别适合野毒株的分离。而根据在BHK - 21细胞系中产生的病毒滴度（TCID₅₀），该细胞系适合大规模病毒培养，适合生产灭活疫苗。
