Analysis Of Wet Feline Infectious Peritonitis Cases And Research The Molecular Characteristics Of Virus S、3c And N Genes

Feline infectious peritonitis(FIP)is a fatal disease of cats,and it is also one of the main diseases that lead to the death of cats.The disease mainly infects kittens under one year old or old cats,and it is high in many cat families,which not only causes great harm to individuals,but also to the whole pet breeding industry.Therefore,this study took 10 positive cases of FIP in Chengdu as the research object,summarized their clinical symptoms and clinical diagnosis,and amplified,sequenced and analyzed the full-length CDS of S,3c and N genes of the virus,in order to provide more data reference and basis for clinical diagnosis and laboratory diagnosis of wet FIP.1.Analysis of 10 wet FIP casesIn order to further enrich and improve the clinical data of FIP,it can provide the basis for future clinical diagnosis,laboratory diagnosis and treatment.In this study,10 cases with typical and highly similar clinical symptoms were collected from nearly100 suspected cases(According to clinical symptoms and detection indexes)in two pet hospitals in Chengdu in 2021.The breed,age,sex,clinical symptoms,blood biochemical index analysis,B-ultrasound and DR examination results,exudate analysis,real-time fluorescence reverse transcription polymerase chain reaction results of cats at the time of onset were comprehensively analyzed,and the treatment methods and effects of positive cases(RT-qPCR result of FCoV was positive,and mutation of virus s gene was detected)were objectively evaluated.The results showed that among the 10 infected cats,4 were British short-tailed cats,3 were Chinese garden cats,and the other 3 were American short-tailed cats,puppet cats and Siamese cats,all aged within one year,with 5 males and 5 females.Clinical symptoms are all accompanied by depression,lethargy and anorexia,and at the same time,the body temperature,heart rate and breathing of the cat have increased to varying degrees.Routine blood examination showed that red blood cells,red blood cell volume and average red blood cell volume concentration were all very low,indicating severe anemia.Total protein content,alanine aminotransferase(ALT)and aspartate amino transferase(AST)will increase,indicating that there is severe inflammation in the body with liver damage.The value of A(serum amyloid A(SAA)in cats is 8 to 20 times higher than the normal value(0-4.9),indicating virus infection.The ball ratio is lower than 0.4,and FIP;is highly suspected clinically.Imaging examination(B-ultrasound and DR examination)can effectively observe the presence of ascites in cats;Ascites were extracted for Fan Li test and the results of coronavirus RT-qPCR were positive.Of the 10 cases,7 cases were treated with GS-441524,subcutaneous injection,4 mg/kg once a day.After the longest continuous treatment for 12 weeks,6cases were cured and 1 case died.2.Cloning and sequence analysis of S,3c and N genes of FIPVIn order to further study the molecular characteristics of FIP virus,RNA was extracted from the ascites of the above 10 cases and reverse transcribed into cDNA.Primers were designed for S gene,3c gene and N gene of FIP virus,and the full-length CDS of FIP virus were amplified by PCR,cloned and sequenced.The results of homology and genetic evolution were analyzed.The full-length CDS of S gene was amplified from 5 strains,the full-length CDS of 3c gene was amplified from7 strains and all 10 strains.Sequence analysis showed that,compared with common FECV,S gene had mutations at several sites,among which all strains had the same mutations at sites 23531 and 23537,from A to T or C,and from T to G,respectively.Compared with ordinary FECV,3c gene is shorter in length,and the same multiple sites are mutated in different degrees.The mutation of N gene is smaller.The phylogenetic tree of S,3c and N genes was constructed.It was found that all clinical strains of S gene and 3c gene were clustered with FIPV in this study,while FEPV was clustered into another big branch,which indicated that S gene and 3c gene had obvious differences between FIPV and FEPV,and could be used to identify FIPV.This study analyzed 10 cases of wet FIP,further clarified the clinical symptoms,blood routine examination results,blood biochemical examination results,B-ultrasound and DR examination results and treatment effect of FIP,amplified and sequenced FIPV in ascites,and analyzed the molecular characteristics of virus genes,thus providing further reference and basis for the diagnosis and treatment of FIP.