Nucleotide sequencing and analysis of 16S rDNA and 16S-23S rDNA internal spacer region (ISR) of Taylorella equigenitalis, as an important pathogen for contagious equine metritis (CEM).

This research investigated the genetic similarities of the Taylorella equigenitalis bacteria, a significant pathogen in contagious equine metritis. The study analyzed the sequence of the 16S rDNA and the internal spacer region (ISR) within the 16S-23S rDNA, highlighting high similarity in the sequences with few differences. The findings also suggest that ISR sequences could be used to effectively distinguish different T. equigenitalis strains.

Introduction and Methodology

• The researchers carried out a detailed examination of a bacteria called Taylorella equigenitalis, which is responsible for causing a contagious equine disease.
• This involved a nucleotide sequencing of two sections of the bacteria’s DNA; firstly the 16S rDNA and secondly the internal spacer region between the 16S rDNA and the 23S rDNA, also known as the ISR.
• They used a primer set for the 16S rDNA which amplified an amplicon approximately 1500 bp (base pairs) long for three different strains of T. equigenitalis. The three strains were NCTC11184(T), Kentucky188, and EQ59.

Detailed Sequencing and Findings

• They found that the 16S rDNA of the six sequences (which included three reference sequences for comparison) were very similar, with only minor differences at a few nucleotide positions.
• The primer set for the ISR also amplified two amplicons around 1300 bp and 1200 bp long for the three examined strains.
• The large ISR-A was approximately 920 bp in length, while the shorter ISR-B was around 830 bp long.
• Sequence alignment of the ISR-A and ISR-B showed that there were around 10 base differences between the NCTC11184(T) and EQ59 strains and between the Kentucky188 and EQ59 strains.
• However, they found only minor differences in the sequences between the ISR-A and ISR-B from NCTC11184(T) and Kentucky188.

Conclusions and Implications

• The area between the 16S rDNA and the 23S rDNA in all the ISR sequences revealed a typical order of the intercistronic tRNAs with a 29 nucleotide spacer; 5′-16S rDNA-tRNA(Ile)-tRNA(Ala)-23S rDNA-3′.
• The findings from this study suggest the ISR region could potentially be used to distinguish different T. equigenitalis strains if sequencing methods are used. This may have important implications for identifying and controlling outbreaks of the equine disease caused by this bacteria.