First report of border disease virus in Melophagus ovinus (sheep ked) collected in Xinjiang, China

First metagenomic sequencing for the analysis of microbial community populations of adults and pupae of Melophagus ovinus in Xinjiang, China

Introduction

Melophagus ovinus, a parasite on the body surface of sheep, directly attacks the host through biting and sucking blood and may also transmit pathogens in the process. There are currently only a few studies on the microbial composition of M. ovinus, while there are no such studies on pupae.

Methods

In this study, samples AT-1 to AT-4 each contained four M. ovinus individuals, while sample AT-5 comprised four M. ovinus pupae, all used for metagenomic sequencing and analysis. Melophagus ovinus adults and pupae were collected from four regions in Xinjiang, China. DNA was extracted from the samples, amplified, and sequenced using the Illumina Novaseq 6000 System; finally, the sequencing data were analyzed using molecular biology software.

Results and discussion

From all samples, a total of 32 phyla, comprising 372 genera and 1,037 species, were detected. The highest microbial diversity was observed in Kuqa City (AT-2) and Qira County (AT-4). Pupae exhibited 40 unique microbial genera (AT-5) but did not have the highest microbial diversity. Proteobacteria was the dominant phylum in all samples. The dominant genera included Bartonella, Wolbachia, Pseudomonas, and Arsenophonus. This is the first study to report most of the bacteria (e.g., Pseudomonas versuta and Arsenophonus nasoniae), fungi (e.g., Saitoella complicata), viruses (e.g., Orf virus and Wolbachia phage WO), and protozoa (e.g., Trypanosoma theileri and Babesia bigemina) in M. ovinus. This study has enriched the microbial diversity data of M. ovinus, and the pathogens it carries may pose a threat to public health safety and the economy of related industries, necessitating further research to develop effective biological control strategies.

Detection of Bartonella schoenbuchensis (sub)species DNA in different louse fly species in Saxony, Germany: The proof of multiple PCR analysis necessity in case of ruminant-associated bartonellae determination

BACKGROUND

Hippoboscid flies are bloodsucking arthropods that can transmit pathogenic microorganisms and are therefore potential vectors for pathogens such as Bartonella spp. These Gram-negative bacteria can cause mild-to-severe clinical signs in humans and animals; therefore, monitoring Bartonella spp. prevalence in louse fly populations appears to be a useful prerequisite for zoonotic risk assessment.

METHODS

Using convenience sampling, we collected 103 adult louse flies from four ked species (Lipoptena cervi, n = 22; Lipoptena fortisetosa, n = 61; Melophagus ovinus, n = 12; Hippobosca equina, n = 8) and the pupae of M. ovinus (n = 10) in the federal state of Saxony, Germany. All the samples were screened by polymerase chain reaction (PCR) for Bartonella spp. DNA, targeting the citrate synthase gene (gltA). Subsequently, PCRs targeting five more genes (16S, ftsZ, nuoG, ribC and rpoB) were performed for representatives of revealed gltA genotypes, and all the PCR products were sequenced to identify the Bartonella (sub)species accurately.

RESULTS AND CONCLUSIONS

The overall detection rates for Bartonella spp. were 100.0%, 59.1%, 24.6% and 75.0% in M. ovinus, L. cervi, L. fortisetosa and H. equina, respectively. All the identified bartonellae belong to the Bartonella schoenbuchensis complex. Our data support the proposed reclassification of the (sub)species status of this group, and thus we conclude that several genotypes of B. schoenbuchensis were detected, including Bartonella schoenbuchensis subsp. melophagi and Bartonella schoenbuchensis subsp. schoenbuchensis, both of which have previously validated zoonotic potential. The extensive PCR analysis revealed the necessity of multiple PCR approach for proper identification of the ruminant-associated bartonellae.

First Report and Genetic Characterization of Border Disease Virus in Sheep from Hulunbuir, Northeastern China

Border disease virus (BDV), a member of the Pestivirus genus within the Flaviviridae family, is known to inflict significant economic losses on livestock farms due to its association with reproductive disorders and persistent infections in sheep and goats. However, comprehensive epidemiological investigations of BDV in China are scarce. This study examined BDV infection in sheep from Hulunbuir, Inner Mongolia, northeastern China, utilizing metagenomic sequencing and polymerase chain reaction (PCR) assay. Among the 96 serum samples analyzed, only one tested positive for BDV nucleotide sequence, yielding a prevalence rate of 1.0%. A total of 11,985 nt long genome sequences was amplified, which showed nucleotide identities ranging from 76.6% to 87.2% and amino acid identities ranging from 85.2% to 93.2% with other BDV strains worldwide. Phylogenetic analysis unequivocally placed the viral strain within genotype BDV-3, showing a close genetic affinity with strain JSLS12-01 identified in Jiangsu province, China. Furthermore, selection pressure analyses suggested that purifying selection predominantly influenced the evolutionary dynamics of BDV genomes. This study marks the inaugural detection of BDV in sheep within Inner Mongolia, northeastern China, thereby enhancing our understanding of the extensive genetic diversity and geographical distribution of BDV strains across the country. These findings hold relevance for the livestock industry and disease surveillance efforts, offering valuable insights into the prevalence and genetic characteristics of BDV in this region.

The genome of sheep ked (Melophagus ovinus) reveals potential mechanisms underlying reproduction and narrower ecological niches

BACKGROUND

Melophagus ovinus is considered to be of great veterinary health significance. However, little is known about the information on genetic mechanisms of the specific biological characteristics and novel methods for controlling M. ovinus.

RESULTS

In total, the de novo genome assembly of M. ovinus was 188.421 Mb in size (330 scaffolds, N50 Length: 10.666 Mb), with a mean GC content of 27.74%. A total of 13,372 protein-coding genes were functionally annotated. Phylogenetic analysis indicated that the diversification of M. ovinus and Glossina fuscipes took place 72.76 Mya within the Late Cretaceous. Gene family expansion and contraction analysis revealed that M. ovinus has 65 rapidly-evolving families (26 expansion and 39 contractions) mainly involved DNA metabolic activity, transposases activity, odorant receptor 59a/67d-like, IMD domain-containing protein, and cuticle protein, etc. The universal and tightly conserved list of milk protein orthologues has been assembled from the genome of M. ovinus. Contractions and losses of sensory receptors and vision-associated Rhodopsin genes were significant in M. ovinus, which indicate that the M. ovinus has narrower ecological niches.

CONCLUSIONS

We sequenced, assembled, and annotated the whole genome sequence of M. ovinus, and launches into the preliminary genetic mechanisms analysis of the adaptive evolution characteristics of M. ovinus. These resources will provide insights to understand the biological underpinnings of this parasite and the disease control strategies.

Distribution and Molecular Epidemiology of Anaplasma ovis in Melophagus ovinus and Small Ruminants in Border Regions of South Xinjiang, China

Background: Anaplasma ovis are obligate intracellular bacteria that can endanger human and animal health, and they can be transmitted by arthropod vectors, such as Melophagus ovinus and ticks. Materials and Methods: In this study, 433 specimens, including 370 M. ovinus and 63 sheep blood samples, were collected from nine districts of South Xinjiang to investigate the distribution and molecular epidemiology of A. ovis in M. ovinus and small ruminant. Results: DNA of A. ovis was detected in 109 (25.2%, 109/433) of the 433 samples using PCR and sequencing. The analysis of A. ovis msp4 sequences revealed four different genotypes, including genotype III (47.7%; 52/109), GB3 (34.0%; 37/109), AoGOv3 (15.6%; 17/109), and XJ9 (2.8%; 3/109). Conclusions: To the best of our knowledge, A. ovis genotypes GB3, AoGOv3, and XJ9 detected in this study are the first to be reported in M. ovinus, and our data indicate that XJ9 is a novel A. ovis genotype presented herein for the first time. These findings provide important references for the new understanding and prevention of A. ovis in border counties in China.

First determination of DNA virus and some additional bacteria from Melophagus ovinus (sheep ked) in Tibet, China

Melophagus ovinus (sheep ked) is one of the common ectoparasites in sheep. In addition to causing direct damage to the host through biting and sucking blood, sheep ked is a potential vector of helminths, protozoa, bacteria, and viruses. Sheep M. ovinus samples from three regions in Tibet were selected for DNA extraction. The 16S rDNA V3-V4 hypervariable region was amplified, after genomic DNA fragmentation, Illumina Hiseq libraries were constructed. The 16S rRNA sequencing and viral metagenomics sequencing were separately conducted on the Illumina Novaseq 6000 platform and molecular biology software and platforms were employed to analyze the sequencing data. Illumina PE250 sequencing results demonstrated that the dominant bacteria phylum in M. ovinus from Tibet, China was Proteobacteria, where 29 bacteria genera were annotated. The dominant bacterial genera were Bartonella, Wolbachia, and Arsenophonus; Bartonella chomelii, Wolbachia spp., and Arsenophonus spp. were the dominant bacterial species in M. ovinus from Tibet, China. We also detected Kluyvera intermedia, Corynebacterium maris DSM 45190, Planomicrobium okeanokoites, and Rhodococcus erythropolis, of which the relative abundance of Kluyvera intermedia was high. Illumina Hiseq sequencing results demonstrated that 4 virus orders were detected in M. ovinus from Tibet, China, and 3 samples were annotated into 29 families, 30 families, and 28 families of viruses, respectively. Virus families related to vertebrates and insects mainly included Mimiviridae, Marseilleviridae, Poxviridae, Ascoviridae, Iridoviridae, Baculoviridae, Hytrosaviridae, Nudiviridae, Polydnaviridae, Adomaviridae, Asfarviridae, Hepeviridae, Herpesviridae, and Retroviridae; at the species level, the relative abundance of Tupanvirus_soda_lake, Klosneuvirus_KNV1, and Indivirus_ILV1 was higher. African swine fever virus and many poxviruses from the family Poxviridae were detected, albeit their relative abundance was low. The dominant bacterial phylum of M. ovinus from Tibet, China was Proteobacteria, and the dominant bacterial genera were Bartonella, Wolbachia, and Arsenophonus, where 23 out of 29 annotated bacteria genera were first reported in M. ovinus. Kluyvera intermedia, Corynebacterium maris DSM 45190, Planomicrobium okeanokoites, and Rhodococcus erythropolis were detected for the first time. All DNA viruses detected in this study have been reported in M. ovinus for the first time.

Research Progress on Emerging Viral Pathogens of Small Ruminants in China during the Last Decade

China is the country with the largest number of domestic small ruminants in the world. Recently, the intensive and large-scale sheep/goat raising industry has developed rapidly, especially in nonpastoral regions. Frequent trading, allocation, and transportation result in the introduction and prevalence of new pathogens. Several new viral pathogens (peste des petits ruminants virus, caprine parainfluenza virus type 3, border disease virus, enzootic nasal tumor virus, caprine herpesvirus 1, enterovirus) have been circulating and identified in China, which has attracted extensive attention from both farmers and researchers. During the last decade, studies examining the etiology, epidemiology, pathogenesis, diagnostic methods, and vaccines for these emerging viruses have been conducted. In this review, we focus on the latest findings and research progress related to these newly identified viral pathogens in China, discuss the current situation and problems, and propose research directions and prevention strategies for different diseases in the future. Our aim is to provide comprehensive and valuable information for the prevention and control of these emerging viruses and highlight the importance of surveillance of emerging or re-emerging viruses.

Possible Arbovirus Found in Virome of Melophagus ovinus

Members of the Lipopteninae subfamily are blood-sucking ectoparasites of mammals. The sheep ked (Melophagus ovinus) is a widely distributed ectoparasite of sheep. It can be found in most sheep-rearing areas and can cause skin irritation, restlessness, anemia, weight loss and skin injuries. Various bacteria and some viruses have been detected in M. ovinus; however, the virome of this ked has never been studied using modern approaches. Here, we study the virome of M. ovinus collected in the Republic of Tuva, Russia. In our research, we were able to assemble full genomes for five novel viruses, related to the Rhabdoviridae (Sigmavirus), Iflaviridae, Reoviridae and Solemoviridae families. Four viruses were found in all five of the studied pools, while one virus was found in two pools. Phylogenetically, all of the novel viruses clustered together with various recently described arthropod viruses. All the discovered viruses were tested on their ability to replicate in the mammalian porcine embryo kidney (PEK) cell line. Aksy-Durug Melophagus sigmavirus RNA was detected in the PEK cell line cultural supernate after the first, second and third passages. Such data imply that this virus might be able to replicate in mammalian cells, and thus, can be considered as a possible arbovirus.

Global Distribution and Genetic Heterogeneity of Border Disease Virus

Border disease virus (BDV) belongs to the genus Pestivirus of the family Flaviviridae. Interspecies transmission of BDV between sheep, cattle, and pigs occurs regularly, sometimes making diagnosis a challenge. BDV can yield substantial economic losses, including prenatal and postnatal infections in lambs, which are the primary source of infection and maintenance of the virus in the population. Since BDV is antigenically and genetically related to bovine viral diarrhea virus (BVDV), it might pose a significant risk to cattle, influencing BVDV eradication campaigns. Similarly, the presence of BDV in swine herds due to pestivirus spillover between small ruminants and pigs might cause uncertainty in classical swine fever virus (CSFV) diagnostics. Therefore, knowledge of BDV epidemiology in different geographical regions will help prevent its spread and optimize control measures. Previous epidemiological studies have shown that various BDV genotypes are predominant in different countries. This review provides an overview of the spread of BDV world-wide in different host species.

Vector-Borne Pathogens with Veterinary and Public Health Significance in Melophagus ovinus (Sheep Ked) from the Qinghai-Tibet Plateau

Melophagus ovinus (sheep ked) is a hematophagous ectoparasite that mainly parasitizes sheep. In addition to causing inflammation, wool loss, and skin damage to the animal hosts, M. ovinus also serves as a vector for a variety of pathogens and is highly likely to participate in the life and transmission cycle of pathogenic organisms. Herein, we investigated the presence and molecular characterization of vector-borne pathogens in M. ovinus from Qinghai-Tibet Plateau, China. A total of 92 M. ovinus pools collected from the Qinghai province of China were screened for the presence of selected vector-borne pathogens. The overall positive rate of A. ovis, A. bovis, A. phagocytophilum, and T. ovis in M. ovinus was 39.1%, 17.4%, 9.8%, and 89.1%, respectively. All of the samples were negative for Border disease virus (BDV), other Anaplasma species, Babesia spp., Rickettsia spp., and Borrelia spp. Co-infection of different Anaplasma species and T. ovis occurred in 51.2% of all samples with T. ovis. The positive rates of A. ovis, A. bovis, and A. phagocytophilum in different regions and altitudes of the sampling sites were significantly different. Sequence and phylogenetic analysis of target genes confirmed their identity with corresponding pathogens. Our results elucidate the occurrence and molecular characterization of Anaplasma spp. and Theileria spp. in M. ovinus, which could act as potential zoonotic reservoirs. To the best of our knowledge, this is the first report of the detection of A. bovis and A. phagocytophilum DNA in M. ovinus. This study gives the first extensive molecular survey of vector-borne pathogens with veterinary and public health significance in M. ovinus from the Qinghai-Tibet Plateau, China.