Research
Performance of various TaqMan and SYBR Green rRT-PCR methods in detecting the Egyptian foot-and-mouth disease viruses
Proficient application of the advanced technology for foot-and-mouth disease virus (FMDV) detection, still a target challenge in Egypt, not only for rapid, identification of the transboundary continuously evolving virus, but also support accurate control strategy involving manufacturing of a high-quality protective vaccine. The article discussed both two real-time RT-PCR (rRT-PCR) methods depending on either fluorophore or fluorescent dye for the precise detection of FMDV few copies. TaqMan based probe/primer overcame SYBR Green-based primer rRT-PCR by 10-fold for detecting less FMDV nucleic acid. In contrary, lower threshold cycles values with fewer nucleic acid copies biased to the fluorescent RRT-PCR with 3-4 cycles earlier. TaqMan format had better sensitivity and specificity, while SYBR Green method displayed less detection limit and precision.
Use of Different Immunoresponse Assays for Evaluation of Live Attenuated Sheep Pox Vaccine in Comparison with Challenge Test
Sheep pox (SP) is one of the priorities, high-impact animal diseases in many developing countries, where live attenuated vaccines are routinely used against sheep pox virus (SPV). Sheep pox virus is a member of the family Poxviridae, genus Capri poxvirus. In this study, live attenuated Sheep pox vaccines were evaluated for humoral and cellular immunity using virus neutralization index (NI), ELISA and lymphocyte proliferation assay (XTT) beside routinely titration of life attenuated virus content of vaccine in Vero cell line which gives mean satisfactory TCID50/dose (3.34) for used vaccine batches, in addition to clinical examination of vaccinated sheep and also application of challenge test. Sixty susceptible lambs were divided into (10) groups and vaccinated with field and safety doses of (10) different batches of live attenuated vaccine intradermal (I/D) in tail fold while three lambs kept as control. The results showed that lymphocyte proliferation began to increase till reach to its peak (1.312) at 10th day post vaccination then decrease after that with re-increasing after challenge , serological assays results revealed that protective serum antibody titer started at 10th day post vaccination with mean titer (1.6 and 1.99), mean absorbance (1.56 and 2.02) and at three weeks the mean titer (2.35 and 2.61) , mean absorbance (2.43 and 2.51) for NI and ELISA respectively, also all vaccinated lambs showed satisfactory levels of protection against the virulent SPV through challenge test as SID50 more than (2.5) for all batches of vaccine. The results demonstrated that vaccine titration in Vero cell line and evaluation of humoral, cellular immuneresponses using different assays for vaccinated lambs were possible to be an accurate parameter for evaluation of life attenuated sheep pox vaccine equivalent the protective results obtained against a virulent SPV in challenge test.
