{"title":"Novel image-based titration method for potency testing of diphtheria toxoid in Vero cell assay.","authors":"Miyuki Kimura, Masaaki Iwaki, Tsuyoshi Kenri, Mitsutoshi Senoh","doi":"10.7883/yoken.JJID.2025.030","DOIUrl":null,"url":null,"abstract":"<p><p>The potency of diphtheria toxoid is determined by titrating neutralizing antibody levels in immunized mice using the Vero cell assay. The WHO manual recommends titration by determining the cytotoxic endpoint through measuring cell metabolism and observing cell morphology under a microscope, which has been conducted in our laboratory; however, the former is time-consuming and the latter subjective. To address these limitations, we have developed a novel endpoint determination method based on cell image analysis. We assessed the feasibility of this image analysis and compared it with microscopic observation and cell metabolism measurement. Consequently, image analysis proved effective for endpoint determination, yielding potency values comparable to existing methods in measuring potencies of commercial vaccines. These findings suggest that image analysis, being objective and convenient, can serve as a reliable alternative method for potency testing of diphtheria vaccines.</p>","PeriodicalId":14608,"journal":{"name":"Japanese journal of infectious diseases","volume":" ","pages":""},"PeriodicalIF":1.1000,"publicationDate":"2025-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Japanese journal of infectious diseases","FirstCategoryId":"3","ListUrlMain":"https://doi.org/10.7883/yoken.JJID.2025.030","RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"INFECTIOUS DISEASES","Score":null,"Total":0}
引用次数: 0
Abstract
The potency of diphtheria toxoid is determined by titrating neutralizing antibody levels in immunized mice using the Vero cell assay. The WHO manual recommends titration by determining the cytotoxic endpoint through measuring cell metabolism and observing cell morphology under a microscope, which has been conducted in our laboratory; however, the former is time-consuming and the latter subjective. To address these limitations, we have developed a novel endpoint determination method based on cell image analysis. We assessed the feasibility of this image analysis and compared it with microscopic observation and cell metabolism measurement. Consequently, image analysis proved effective for endpoint determination, yielding potency values comparable to existing methods in measuring potencies of commercial vaccines. These findings suggest that image analysis, being objective and convenient, can serve as a reliable alternative method for potency testing of diphtheria vaccines.
期刊介绍:
Japanese Journal of Infectious Diseases (JJID), an official bimonthly publication of National Institute of Infectious Diseases, Japan, publishes papers dealing with basic research on infectious diseases relevant to humans in the fields of bacteriology, virology, mycology, parasitology, medical entomology, vaccinology, and toxinology. Pathology, immunology, biochemistry, and blood safety related to microbial pathogens are among the fields covered. Sections include: original papers, short communications, epidemiological reports, methods, laboratory and epidemiology communications, letters to the editor, and reviews.