Identification of Potential Vaccine Strains of Escherichia coli Isolates From Diarrhoeic Calves
Yasemin Erdoğan, Ediz Kağan Özgen, Murat Özmen, Elif Karadeniz Pütür, Nebahat Polat, Ersan Pütür, Mücahit Harmancı, Ercan Atalay, Ahmet Temur, Meryem Güloğlu, Lütfullah Celep, Seyda Cengiz, Mehmet Cemal Adıgüzel, Cihan Öz, Timur Gülhan, Alper Çiftci, Erhan ÇiftgülABSTRACT
Background
Escherichia coli is the most commonly isolated bacterium in cases of diarrhoea in calves under the age of 2 months.
Objectives
This study aimed to identify E. coli strains with immunogenic potential by characterizing isolates from diarrheic calves through antigenic profiling and genotyping.
Methods
The phenotypic and genotypic antibiotic resistance characteristics and virulence genes of the E. coli strains isolated from 500 faecal samples were examined, of which 88 were further genotyped using the Multiple‐Locus Variable‐Number Tandem Repeat Analysis (MLVA) method. Subsequently, 20 E. coli strains were selected based on their antibiotic resistance patterns and genetic typing (MLVA) results, and subjected to an analysis of their outer membrane vesicle profile.
Results
Among these, strains Ec048 and Ec026 exhibited high OMV diversity and were identified as promising candidates for further immunogenic evaluation. Immunization of experimental animals with these strains enhanced humoural immune responses (IgG, IgM, CD20), whereas cellular immune parameters (CD4, CD8) showed no significant change.
Conclusions
In conclusion, the study demonstrates that strains Ec048 and Ec026 elicit strong humoural immune responses, indicating their potential for vaccine development. However, protective efficacy was not assessed, and further studies including challenge experiments are required to confirm their suitability as vaccine strains.