ABSTRACT
Objective@#To carry out a investigation on molecular epidemiological features of tick-borne Brucella in Xinjiang Uygur Autonomous Region (Xinjiang), and to provide a scientific basis for formulation of effective preventive and control measures.@*Methods@#In 2016-2018, parasitic ticks (including engorged females) were collected on the body surface of livestock in 10 counties (cities) along the border of Xinjiang. The free-living ticks were collected by flagging method in Alashankou. The engorged female was placed in a breathable insect tube for spawning, each egg batch was divided into two parts: one part was tick eggs, while the second part was allowed further larval development. All ticks were identified by molecular biology (16S rRNA) identification. Tick DNA was extracted, PCR was performed based on Brucella omp22 and IS711, and amplification products were sequenced and analyzed by BLAST.@*Results@#A total of 1 084 ticks were collected in 11 counties (cities), of them 747 were parasitic ticks (including 34 engorged females) and 337 were free-living ticks. Based on 16S rRNA identification, 1 084 ticks belonged to 4 genera and 5 species, and the proportions of Dermacentor nuttalli, Dermacentor marginatus, Haemaphysalis punctata, Hyalomma asiaticum and Rhipicephalus turanicus were 29.43% (319/1 084), 16.51% (179/1 084), 10.42%(113/1 084), 37.27% (404/1 084), and 6.37% (69/1 084), respectively. A total of 214 Brucella-positive nucleic acid samples were detected, the positive rate was 19.74%. The parasitic ticks' positive rate was 25.30% (189/747), and the free-living ticks' positive rate was 7.42% (25/337), parasitic ticks' positive rate was higher than that of free-living ticks (χ2=46.873, P < 0.05). Two Brucella melitensis nucleic acid samples were detected in 34 "engorged females-tick eggs" developmental stage, and one Brucella melitensis nucleic acid sample was detected in 22 "tick eggs-larvae" developmental stage.@*Conclusions@#Brucella is widely distributed in parasitic ticks and free-living ticks in Xinjiang border areas, and the parasitic ticks' positive rate is obviously higher than that of free-living ticks. The Brucella melitensis has potential transovarian transmission and transstadial transmission in ticks. In the prevention and control of livestock brucellosis, the work of killing ticks should be strengthened, including parasitic ticks on the body surface and free-living ticks in the environment.
ABSTRACT
Objective To carry out a investigation on molecular epidemiological features of tick-borne Brucella in Xinjiang Uygur Autonomous Region (Xinjiang), and to provide a scientific basis for formulation of effective preventive and control measures. Methods In 2016 - 2018, parasitic ticks (including engorged females) were collected on the body surface of livestock in 10 counties (cities) along the border of Xinjiang. The free-living ticks were collected by flagging method in Alashankou. The engorged female was placed in a breathable insect tube for spawning, each egg batch was divided into two parts: one part was tick eggs, while the second part was allowed further larval development. All ticks were identified by molecular biology (16S rRNA) identification. Tick DNA was extracted, PCR was performed based on Brucella omp22 and IS711, and amplification products were sequenced and analyzed by BLAST. Results A total of 1084 ticks were collected in 11 counties (cities), of them 747 were parasitic ticks (including 34 engorged females) and 337 were free-living ticks. Based on 16S rRNA identification, 1084 ticks belonged to 4 genera and 5 species, and the proportions of Dermacentor nuttalli, Dermacentor marginatus, Haemaphysalis punctata, Hyalomma asiaticum and Rhipicephalus turanicus were 29.43％ (319/1084), 16.51％ (179/1084), 10.42％(113/1084), 37.27％ (404/1084), and 6.37％ (69/1084), respectively. A total of 214 Brucella-positive nucleic acid samples were detected, the positive rate was 19.74％. The parasitic ticks' positive rate was 25.30％ (189/747), and the free-living ticks' positive rate was 7.42％ (25/337), parasitic ticks' positive rate was higher than that of free-living ticks (χ2 = 46.873, P < 0.05). Two Brucella melitensis nucleic acid samples were detected in 34 "engorged females-tick eggs" developmental stage, and one Brucella melitensis nucleic acid sample was detected in 22 "tick eggs-larvae" developmental stage. Conclusions Brucella is widely distributed in parasitic ticks and free-living ticks in Xinjiang border areas, and the parasitic ticks' positive rate is obviously higher than that of free-living ticks. The Brucella melitensis has potential transovarian transmission and transstadial transmission in ticks. In the prevention and control of livestock brucellosis, the work of killing ticks should be strengthened, including parasitic ticks on the body surface and free-living ticks in the environment.
ABSTRACT
To carry out pathologic diagnoses and whole-genome sequence analyses of the Jaagsiekte sheep retrovirus (JSRV) in Xinjiang, China, we first observed sheep suspected to have the JSRV. Then, the extracted virus suspension was observed by transmission electron microscopy (TEM). Total RNAs from lungs of JSRV-infected sheep were extracted and reverse-transcribed using a cDNA synthesis kit. Six pairs of primers were designed according to the exogenous reference virus strain (AF105220). Reverse transcription-polymerase chain reaction was carried out from JSRV-infected tissue, and the whole genome of the JSRV sequenced. Our results showed: flow of nasal fluid ("wheelbarrow test"); different sizes of adenoma lesions in the lungs; papillary hyperplasia of alveolar epithelial cells; alveolar cavity filled with macrophages; dissolute nuclei in central lesions. TEM revealed JSRV particles with a diameter of 88 nm to 125. 4 nm. The full-length of the viral genome sequence was 7456 bp. BLAST analyses showed nucleotide homology of 96% and 95% compared with that of the representative strain from the USA (AF105220) and UK (AF357971). Nucleotide homology was 89.8% and 89.9% compared with the endogenous Jaagsiekte sheep retrovirus, Inner Mongolia strain (DQ838493) and USA strain (EF680300). The specific pathogenic amino-acid sequence "YXXM" was found in the TM district, similar to the exogenous JSRV: this gene has been reported to be oncogenic. This is the first report of the complete genomic sequence of the exogenous JSRV from Xinjiang, and could lay the foundation for study of the biological characteristics and pathogenic mechanisms of the pulmonary adenomatosis virus in sheep.