ABSTRACT
Background@#Feline calicivirus (FCV) is a common pathogen of felids, and FCV vaccination is regularly practiced. The genetic variability and antigenic diversity of FCV hinder the effective control and prevention of infection by vaccination. Improved knowledge of the epidemiological characteristics of FCV should assist in the development of more effective vaccines. @*Objectives@#This study aims to determine the prevalence of FCV in a population of cats with FCV-suspected clinical signs in Hangzhou and to demonstrate the antigenic and genetic relationships between vaccine status and representative isolated FCV strains. @*Methods@#Cats (n = 516) from Hangzhou were investigated between 2018 and 2020. The association between risk factors and FCV infection was assessed. Phylogenetic analyses based on a capsid coding sequence were performed to identify the genetic relationships between strains. In vitro virus neutralization tests were used to assess antibody levels against isolated FCV strains in client-owned cats. @*Results@#The FCV-positive rate of the examined cats was 43.0%. Risk factors significantly associated with FCV infection were vaccination status and oral symptoms. Phylogenetic analysis revealed a radial phylogeny with no evidence of temporal or countrywide clusters. There was a significant difference in the distribution of serum antibody titers between vaccinated and unvaccinated cats. @*Conclusions@#This study revealed a high prevalence and genetic diversity of FCV in Hangzhou. The results indicate that the efficacy of FCV vaccination is unsatisfactory. More comprehensive and refined vaccination protocols are an urgent and unmet need.
ABSTRACT
Background@#Feline calicivirus (FCV) is a common pathogen of felids, and FCV vaccination is regularly practiced. The genetic variability and antigenic diversity of FCV hinder the effective control and prevention of infection by vaccination. Improved knowledge of the epidemiological characteristics of FCV should assist in the development of more effective vaccines. @*Objectives@#This study aims to determine the prevalence of FCV in a population of cats with FCV-suspected clinical signs in Hangzhou and to demonstrate the antigenic and genetic relationships between vaccine status and representative isolated FCV strains. @*Methods@#Cats (n = 516) from Hangzhou were investigated between 2018 and 2020. The association between risk factors and FCV infection was assessed. Phylogenetic analyses based on a capsid coding sequence were performed to identify the genetic relationships between strains. In vitro virus neutralization tests were used to assess antibody levels against isolated FCV strains in client-owned cats. @*Results@#The FCV-positive rate of the examined cats was 43.0%. Risk factors significantly associated with FCV infection were vaccination status and oral symptoms. Phylogenetic analysis revealed a radial phylogeny with no evidence of temporal or countrywide clusters. There was a significant difference in the distribution of serum antibody titers between vaccinated and unvaccinated cats. @*Conclusions@#This study revealed a high prevalence and genetic diversity of FCV in Hangzhou. The results indicate that the efficacy of FCV vaccination is unsatisfactory. More comprehensive and refined vaccination protocols are an urgent and unmet need.
ABSTRACT
Objective:To highly express the secretory gene engineering anti CD20F(ab') 2 in the E.coli,simplify working processes and enhance the bioactivity of the antibody fragment.Methods:Using the single factor analysis to optimize the ferment parameters.A culture method which most suit for E.coli secreting anti CD20F(ab') 2 was selected.The anti CD20F(ab') 2 was extracted from periplasm then purified it using the strptococal protein G affinity colume and the S200 HR size exclusion chromatography.The activity of anti CD20F(ab') 2 inhibiting the growth of cell Daudi in vitro was eamined using MTT.Results:Using the optimized culture method,the yield of anti CD20F(ab') 2 was distinctly enhanced from 1.9～2.2 mg/L to 3.7～4.3 mg/L and the proportion of anti CD20F(ab') 2 in all the extract also was improved from 9.7～13.2% to 38.1%～46.8%.After the S200 HR size exclusion chromatography,the purity of anti CD20F(ab') 2 could exceed 85%.The outcome of MTT exmiination showed the IC 50 of anti CD20F(ab') 2 and Fab' were 14.6 ?g/ml and 39.5 ?g/ml,respectively.Conclusion:The gene engineering anti CD20F(ab') 2 could highly express in the E.coli by using the optimized culture method.The anti CD20F(ab') 2 inhibited the growth of Daudi cells in vitro more strong than anti CD20Fab'.