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. 2022 Sep 5;11(9):1016.
doi: 10.3390/pathogens11091016.

Epidemiological and Phylogeographic Study of Equid Herpesviruses in Tunisia

Chaima Badr  1 , Oussama Souiai  2 , Marwa Arbi  2 , Imen El Behi  1 , Mohamed S Essaied  3 , Ines Khosrof  3 , Alia Benkahla  2 , Ahmed Chabchoub  3   4 , Abdeljelil Ghram  1
Affiliations

Epidemiological and Phylogeographic Study of Equid Herpesviruses in Tunisia

Chaima Badr et al. Pathogens. .

Abstract

Equid herpesvirus (EHV) is a contagious viral disease affecting horses, causing illness characterized by respiratory symptoms, abortion and neurological disorders. It is common worldwide and causes severe economic losses to the equine industry. The present study was aimed at investigating the incidence of EHVs, the genetic characterization of Tunisian isolates and a spatiotemporal study, using 298 collected samples from diseased and clinically healthy horses. The global incidence of EHV infection was found to be about 71.81%. EHV2 and EHV5 were detected in 146 (48.99%) and 159 (53.35%) sampled horses, respectively. EHV1 was detected in 11 samples (3.69%); EHV4 was not detected. Co-infections with EHV1-EHV2, EHV1-EHV5 and EHV2-EHV5 were observed in 0.33%, 1.34% and 31.54% of tested horses, respectively. Phylogenetic analyses showed that gB of EHV2 and EHV5 displays high genetic diversity with a nucleotide sequence identity ranging from 88 to 100% for EHV2 and 97.5 to 100% for EHV5. Phylogeography suggested Iceland and USA as the most likely countries of origin of the Tunisian EHV2 and EHV5 isolates. These viruses detected in Tunisia seemed to be introduced in the 2000s. This first epidemiological and phylogeographic study is important for better knowledge of the evolution of equid herpesvirus infections in Tunisia.

Keywords: EHV1; EHV2; EHV5; Tunisia; epidemiology; equine; gB; herpesvirus; phytogeography.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Time scaled Maximum Clade Credibility (MCC) tree representing geographic origins of equid herpesviruses 2 and 5 isolated in Tunisia. Tree colors reflect the most common ancestral geographic origin of tree nodes and branches. TMRCA and their 95% HPD of Tunisian isolates are indicated in the tree. Tunisian isolates identified in this study are indicated in Bold.
Figure 2
Figure 2
Spatiotemporal dynamics tracking the historical origin of equid herpesviruses 2 and 5 isolated in Tunisia. Lines connecting between countries represent branches in the MCC tree. Lines in blue indicate the virus transmission from Tunisia to other countries.
Figure 3
Figure 3
Chord diagram representing the identified herpesvirus transitions between countries with their Bayes Factor (BF). Chord width is proportional to BF. Bayes Factors for each transition are indicated in the figure. A transition with BF > 3 is statistically supported.
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