Epidemiological Investigation Of Upper Respiratory Diseases In Cats In Some Areas Of Shandong And Analysis Of VP1 Gene Sequences Of Calicivirus

Feline upper respiratory tract disease is one of the most common diseases in small animals.It is an infectious disease with sneezing,runny nose and increased eye secretions as the main symptoms,which seriously harms the life and health of cats.The main pathogens causing this disease are feline herpesvirus type Ⅰ(FHV-1),feline calicivirus(FCV),mycoplasma(Mf),chlamydia feline(Cf)and Bordetella bronchiseptica(Bb),among which feline calicivirus has a high incidence in clinical practice,and its variation is great,and immune failure often occurs.For this reason,this study takes cats in some areas of Shandong Province as the research object,makes a statistical investigation on the epidemic situation of FURTD,and summarizes and analyzes the infection characteristics of different pathogens of FURTD under different conditions,in order to provide some theoretical basis and data reference for the prevention and treatment of FURTD.From March 2021 to February 2023,cases of FURTD were investigated in 21 animal hospitals in some areas of Shandong Province.The contents of the investigation include the gender,age,onset time,immunity,pathogen,feeding environment,clinical symptoms and laboratory results of the cat,statistics of infection characteristics of different pathogens under the same conditions;the VP1 gene sequences of two FCV strains were obtained from diseased cats for homology and phylogenetic tree analysis.Among the 564 cases investigated,457 cases were confirmed,among which 85 cases were infected with FHV-1,and the infection rate was 18.60%.291 cases were infected with FCV,and the infection rate was 63.68%.217 cases were infected with Mf,and the infection rate was 47.48%.60 cases were infected with Cf,and the infection rate was 13.13%.76 cases were infected with Bb,and the infection rate was 16.63%.The incidence of this disease is 54% in males and 46% in females,there is no obvious correlation between the incidence of this disease and gender.The disease occurs in all ages,and the highest incidence rate is57.75% at the age of 0～3 months,and the infection rate of different pathogens is related to age.The infection rate of FCV in cats over one year old is obviously higher,accounting for76.27%.The disease is high in summer and winter,and the most common species is British short-haired cat,accounting for 40.48%;Followed by the puppet cat and the Chinese pastoral cat,accounting for 19.47% and 14.44% respectively.In terms of immunity,the incidence of non-immunized cats is the highest,accounting for 43.33%,and the infection rates of different pathogens are also related to immunity.The incidence of single cat family in feeding environment is high,accounting for 60.61%,The mixed infection rate is obviously higher in the environment with many cats.The most common symptoms after illness are sneezing,runny nose and increased eye secretions.There is a clear correlation between pathogens and symptoms,and Mf infection rate is high in cases with eye symptoms.The infection rate of FCV in patients with stomatitis is extremely high.Most sick cats are accompanied by the increase of SAA,FHV-1,Mf and Bb in the main pathogens can cause high acute inflammatory response,and the cure rate can reach more than 80% by taking effective symptomatic treatment.Some cases also develop into chronic irreversible cases.The sequences of two sample strains obtained by collecting diseased materials were named Ji Nan and Tai An respectively.The nucleotide sequence homology between the two strains and VP1 gene of FCV in NCBI database is between 71.5% and 85.4%.The amino acid sequence homology is between 78.8% and 91.9%.The phylogenetic tree of nucleotide showed that Ji Nan and vaccine strain F4 belonged to the same branch,but the genetic relationship between the two samples and vaccine strain was far away.It shows that the mutation and evolution speed of FCV is fast,and the genetic relationship between strains in different time and region is far different,which also makes the immune effect of core vaccine worse.The above results show that five different pathogens of FURTD are prevalent in some areas of Shandong Province,and the infection is affected by many factors.FCV shows obvious genetic diversity,which brings great challenges to vaccine development and diagnostic technology innovation of this disease.