Molecular characterization of foot-and-mouth disease Virus recently recovered in Zambezi region, Namibia
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Date
2020
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Publisher
Sokoine University of Agriculture
Abstract
Foot-and-mouth disease (FMD) is a severe highly contagious viral disease of clovenhoofed
animals that has significant economic impacts. FMD causes significant economic
loss in Namibia in which the molecular epidemiology of FMD virus (FMDV) responsible
for the outbreaks has not been consistently studied. The general objective of this study was
to determine molecular characteristics of FMD viruses of 2019 outbreak in Zambezi
region, Namibia. A total of 11 epithelial tissue samples collected from cattle showing FMD
clinical signs were used in this study. The RNA extraction and detection of FMDV genome
was done by One-step Reverse Transcription Polymerase Chain Reaction (RT-PCR) of 5’
untranslated region (5’UTR) using universal primers. Typing and sequencing was
performed using serotype-specific oligonucleotide primers. Phylogenetic analysis was
performed using distance matrix neighbour joining method employing the Kimura-2-
parameter option. The findings indicated that all 8 sequenced viruses revealed 100%
nucleotide identity among themselves. Phylogenetic analysis of 36 sequences including 8
sequences of this study, 7 from publication and other sequences from GenBank revealed
that the 2019 isolates clustered together with historic Namibian isolates and those from
neighbouring countries. In-depth typing and phylogeny proved that SAT3 viruses of
topotype II were responsible for 2019 outbreak. Further analysis revealed that the 2019
isolates closely related to isolates from Botswana, some isolates from Zimbabwe and
Kenya but were distantly related to isolates from Zambia and South Africa and no genetic
linkage with isolate from Uganda. These findings indicate that topotype II SAT 3 FMD
viruses were involved in the 2019 FMD outbreak in Zambezi region, Namibia. Further indepth
studies are required to elucidate transmission dynamics and factors associated with
the outbreaks so that appropriate FMD control measure (s) in Namibia can be
recommended.
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Keywords
Molecular characterization, Mouth disease Virus, Foot disease Virus, Zambezi region, Namibia