Abstract
Melophagus ovinus (sheep ked) is a blood-sucking ectoparasite that is parasitic primarily on sheep. It is widely distributed in different geographical regions worldwide. In China, it has been mainly found in Xinjiang, Gansu, and Tibet in recent years. In addition to causing direct damage to the animal hosts, M. ovinus also carries pathogens and serves as a vector for disease transmission. Border disease virus (BDV) is a positive-sense, single-stranded RNA pestivirus that mainly infects and causes border disease (BD) in sheep and goats worldwide. Since 2012, this disease has been reported in 4 provinces in China. In the present study, we investigated the presence of BDV in M. ovinus from Xinjiang and Gansu. Frozen M. ovinus collected during 2017 and 2018 from Xinjiang and Gansu and preserved in our laboratory were studied. First, total RNA of M. ovinus was extracted, followed by reverse transcription, PCR (RT-PCR) amplification of the 5′-UTR of BDV, and sequencing of the amplified products. Finally, the sequencing results were analyzed using DNAStar, MEGA 5.0 molecular biology software, and the BLAST online platform. The results from RT-PCR and sequencing analyses showed that among the samples included in the study, only the M. ovinus collected from Qinghe County in Alta, Xinjiang in 2018 tested positive for BDV. BLAST analysis showed that the viral strain with the most similar nucleotide identity to the sequence of the China/BDV/2018 fragment was the goat-derived BDV strain AH12-02 collected in Anhui, China, in 2012. A phylogenetic-tree analysis showed the strain to exhibit a BDV-3 genotype. This is the first report globally on BDV detected in M. ovinus and is also the first report of BDV discovered in Xinjiang, China. This study reconfirms the presence of BDV in China.
Highlights
Melophagus ovinus is a member of Hippoboscidae (Diptera: Hippoboscoidea) and is a blood-sucking ectoparasite of livestock and wild animals
The results from total RNA extraction of M. ovinus, cDNA synthesis, PCR amplification of the 50-untranslated regions (UTR) of Border disease virus (BDV), sequencing, and sequence analyses showed that only 7 M. ovinus from the Qinghe County in Xinjiang collected in 2018 were positive for BDV-specific PCR amplification
The sequencing results showed that the sequence of the 50-UTR gene was identical in 7 samples, and the sequence was named China/BDV/2018
Summary
Melophagus ovinus (sheep ked) is a member of Hippoboscidae (Diptera: Hippoboscoidea) and is a blood-sucking ectoparasite of livestock and wild animals. China has reported at least 13 pathogens detected in M. ovinus [2,3,4,5,6]. In 2012, the isolation of BDV was first reported in China in the provinces of Anhui and Jiangsu from the serum and tissue samples of goats with persistent diarrhea [23]. In 2012, the total positive rate of BDV antibodies detected in 5 regions of the Jiangsu province was 44.38%, of which the positive rate in that of sheep and goats was 33.33% and 46.32%, respectively [13]. In 2017, a report from China found that the positivity rate of BDV antibodies was 18.29% (400/2187) in the serum of Ovis aries from the Maqu County, Luqu County, and Tianzhu Tibetan Autonomous County in Gansu, as well as from Linzhi City in Tibet [25]
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