Annotation: 
                            The article is devoted to the current problem of differential diagnosis of diseases of viral etiology in 
farm animals. Viral diseases are currently widespread, occupy a leading role in the infectious pathology of farm 
animals, causing enormous economic damage. Given the magnitude of animal vaccine prophylaxis, in order to 
increase the effectiveness of antiepizootic measures, the urgent issue i s the development of methods for the rapid 
and effective detection and differentiation of field and vaccine strains of the infectious rhinotracheitis virus in 
cattle. The possibility of using a polymerase chain reaction to identify and differentiate a vacc ine strain from 
epizootic  strains  and  isolators  of  the  cattle  infectious  rhinotracheitis  virus  is  considered.  In  the  process  of 
research, a PCR-RFLP analysis method was developed to detect the IRT virus in the test material. The PCRRFLP analysis method was used to identify and differentiate the vaccine strain TK-A form  epizootic strains and 
isolators of the cattle IRT virus. The principle of PCR, based on repeated repetition of DNA cycles, annealing 
and synthesis, which leads to an increase in the number of specific DNA fragments of the pathogen, allows you 
to take into account the results of PCR in an agarose gel. Analysis time is about 30 hours. The sensitivity of 
detecting  viral  DNA  is  1-10  picograms  (102  TCD).  Due  to  characteristics  such  as  relative  simplicity  and 
reaction rate, high sensitivity, specificity and reproducibility, PCR has recently become widespread in basic and 
applied research in various fields of biological science, including veterinary virology. 
The results obtained during the studies show that the use of PCR-RFLP allows to differentiate field and 
vaccine strains and isolates of the IRT virus with a high degree of reliability. The use of PCR -RFLP analysis 
increases the efficiency and informativeness of studies in the molecular epizootol ogy of cattle RTI, as it allows 
not only to identify the DNA of different virus strains regardless of their nature, but also to differentiate between 
them, including differentiating the strain TK-A used for the production of attenuated vaccines against epizootic 
strains and isolates of the virus.
                        
                        
                        
                            
                            Year of release:                             
                                2020                            
                        
                        
                            
                            Number of the journal:                             
                                2(78)                            
                        
                        
                        
                     
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