Detection And Infection Of Toxoplasma Gondii In Ticks In Parts Of Xinjiang Establishment Of The New Zealand Rabbit Model

Toxoplasma gondii is an important obligate intracellular parasitic zoonotic protozoa,which is widely prevalent in the world,which can lead to abortion,stillbirth,malformed fetus,etc.in severe cases,causing death in severe cases,causing great harm to human and animal health.In this study,molecular biology was used to investigate the carrier of Toxoplasma gondii in ticks in some areas of Xinjiang and analyze its genotype distribution characteristics.Using the New Zealand white rabbit as the experimental animal,an infection model of Toxoplasma gondii and Blood tick longhorn was established,and the transmission route of Toxoplasma gondii in Blood Tick longhorn was explored,in order to provide basic data for the biological study of Toxoplasma vector.1.From July 2018 to July 2021,2297 tick samples were collected in 15 districts of Xinjiang Uygur Autonomous Region,including Ili,Wensu,Yecheng,Huocheng,Cha County,Pishan County,Fuyun,Habahe,Burjin,Nilek and Jimsar.Based on the B1 locus of Toxoplasma gondii,all DNA samples were detected by PCR,and the carrier rate of Toxoplasma gondii in ticks in Xinjiang was 3.3%(76/2297).Among them,ticks in Ili region had the highest carrier rate of 7.6%(33/434),and ticks in Burzin region had the lowest carrier rate of 2.5%(14/544).Classified by tick species,the carrier rate of Toxoplasma gondii was 4.7%(19/399),that of Toxoplasma fanhead was 3.9%(21/534),that of Toxoplasma regurgitatum was 2.7%(30/1334),and that of ticks of unidentified genus was not detected in Toxoplasma gondii.Based on the Toxoplasma gondii SAG3 and GRA6 gene loci,76 Toxoplasma positive DNA samples obtained in this institute were genotypically identified by enzyme digestion,and the results showed that 76 Toxoplasma genotypes were all type I at the two genoloci.The results showed that the carrier rate of Toxoplasma tick in Xinjiang was low,and there were certain differences in the carrying of Toxoplasma gondii in different tick species,and their genotypes were all type I.2.To explore whether the longhorned blood tick can be a biological carrier of Toxoplasma gondii,Toxoplasma gondii(RH)strain was used as the strain,and a model of acute infection of Toxoplasma gondii in New Zealand white rabbit was first constructed,and Toxoplasma trophozoites with 5 × 104 intraperitoneal fluid dilute to white rabbit were injected with sterile normal saline.Based on the Toxoplasma gondii B1 gene locus,the blood DNA samples of four New Zealand white rabbits were detected by PCR,and it was found that Toxoplasma gondii could be detected in the blood 6 days after the New Zealand white rabbit inoculation strain.No Toxoplasma infection was found in the saline control group of the New Zealand white rabbit.On the 4th day of inoculation of the New Zealand white rabbit,30 longhorned blood ticks,30 hungry adult ticks,starving nymph ticks and starving larvae ticks were selected for bite infection on the body surface of the New Zealand white rabbit.Based on the Toxoplasma gondii B1 locus,DNA samples that bite ticks at different stages of New Zealand white rabbits were detected by PCR.However,Toxoplasma gondii was not detected in eggs at various developmental stages after molting of the longhorned blood tick,either the starvation tick or the starvation adult tick.The results showed that the infection model of New Zealand white rabbit-toxoplasma gondii animals was successfully constructed,and Toxoplasma gondii could enter the tick through the blood sucking of the longhorn tick,and could not be transmitted to the next developmental stage through vertical transmission and intermediate transmission.In summary,the results showed that ticks in Xinjiang carried Toxoplasma gondii,and the genotypes were all classical type I genotype strains.A model of animal infection of the New Zealand white rabbitToxoplasma gondii-Haemaphysalis longicornis was successfully established,and it was found that the Haemaphysalis longicornis was mechanically carried by Toxoplasma gondii and could not be transmitted vertically and periodically.The results of the study provide basic data for the epidemiological investigation and vector transmission of animal toxoplasmosis in China.