Abstract:
Respiratory disease caused by Mannheimia haemolytica is
a major economic and welfare concern in the cattle and
small stock industry worldwide. Disease occurs due to the
interaction of numerous factors, including weaning stress,
shipment, inclement weather, and overcrowding coupled
with viral and bacterial infections. The whole genome of M.
haemolytica strain Mh10517 was analyzed using an Illumina
MiSeq high throughput sequencing platform. The genome
size is 2.67 Mb with 2,879 predicted gene sequences.
The molecular evolution and relatedness of M. haemolytica
was investigated using nucleotide sequence data of seven
housekeeping gene fragments from 21 ovine isolates. MEGA
version 7.0 genomic workbench was used for alignment and
analysis of the nucleotide data sets. For each gene fragment,
the sequences were compared and isolates with identical
sequences were assigned the same allele number. Results suggested that the 21 isolates belonged to six sequence
types (ST) and ST 28 accounted for 33% of the isolates.
Neighbour joining method was used to produce dendograms
based on the concatenated sequences of the seven loci
in multilocus allelic profile. There was significant variation
between the number of synonymous and non-synonymous
substitutions between each sequence pairs (p=0.018)
based on results from the Fisher’s exact test of neutrality of
sequence pairs.
These preliminary data show substantial sequence variations
and this supports the hypothesis that ovine isolates of M.
haemolytica are more diverse that what has been reported
for isolates from other species. These results will advance
studies on various aspects of the biology of M. haemolytica in
Africa, and the world at large.
Description:
Poster presented at the University of Pretoria, Faculty of Veterinary Science Faculty Day, September 07, 2017, Pretoria, South Africa.
Includes bibliographical references
