The present investigation deals with the characterization of defective interfering (DI) particles of Peste-des-petits ruminants (PPR) vaccine Sungri/96 strain generated as a result of high MOI in Vero cells. During the serial 10 passages, infectivity titres drastically reduced from 6.5 to 2.25 log₁₀TCID₅₀/ml at high MOI. Further, attenuation of CPE with high MOI indicated generation of DI particles that resulted in no/slow progression of CPE during the late passages. Monoclonal antibody based cell ELISA indicated normal protein (N & H) packaging in samples with DI activity. At genomic level, inconsistency in amplicon intensity of H gene was observed in RT-PCR, indicating a possible defect of H gene. Further analysis of copy number of PPRV by RT-qPCR indicated intermittent fluctuations of viral genomic RNA copies. The significant decline of viral RNA copies with MOI 3 (314 copies) compared to low MOI (512804 copies), proved that higher DI multiplicities cause more interference with the replication process of the standard virus. Therefore, MOI is critical for manufacturing of vaccines. These investigations will help in upscaling of PPR vaccines in view of ongoing National and Global PPR control and eradication programme.

本研究的目的是鉴定在Vero细胞中高MOI产生的Peste-des-petits反刍动物（PPR）疫苗Sungri / 96菌株的缺陷干扰（DI）颗粒的特性。在连续10次传代过程中，传染性滴度从6.5急剧下降至2.25 log ₁₀ TCID ₅₀/ ml，高MOI。此外，具有高MOI的CPE的衰减表明DI颗粒的产生，其导致在后期传代期间CPE没有/缓慢进行。基于单克隆抗体的细胞ELISA表明样品中具有DI活性的正常蛋白质（N＆H）包装。在基因组水平上，在RT-PCR中观察到H基因的扩增子强度不一致，表明H基因可能存在缺陷。通过RT-qPCR进一步分析PPRV的拷贝数表明病毒基因组RNA拷贝存在间歇性波动。与低MOI（512804拷贝）相比，MOI 3（314拷贝）的病毒RNA拷贝显着下降，证明更高的DI多重性对标准病毒的复制过程产生更多干扰。因此，MOI对疫苗的生产至关重要。