Molecular Epidemiological Investigation And Genetic Diversity Analysis Of Anaplasmas Cattle And Goats In Hainan

Anaplasmosis is a type of rickettsial disease transmitted by tick-borne Anaplasma spp.Anaplasma belongs to Rickettsiales,Anaplasmataceae and Anaplasma.The main types are A.phagocytophilum,A.bovis,A.ovis,A.capra,A.bovis,and A.marginale.After infection,cattle and goats will show clinical symptoms such as emaciation,anemia and jaundice,resulting in slow weight gain and,in severe cases,death,resulting in serious economic losses.Hainan is located in tropical and subtropical areas,with a wide range of tick species and a wide range of activities.Cattle and goats have a greater risk of infection anaplasmosis.The prevalence and molecular characteristics of Anaplasmas cattle and goats have not been reported in Hainan at present.In this study,nested PCR and conventional PCR methods were used to detect the anaplasmas in black goats(N=731)in 18 cities and counties in Hainan,and cattle(N=176)in 4 cities and counties in Hainan.The results showed that the total Anaplasma spp infection rates of black goats and cattle were 30.1% and 14.8%,respectively.In black goats,the infection rates of A.bovis,A.pagocytophilum,A.ovis,and A.capra were22.7%,13.8%,2%,and 3.4%,respectively.In cattle,the infection rates of A.bovis,A.pagocytophilum,and A.marginale were 11.4%,6.3%,and 5.7%,respectively.This study found that black goats and cattle in different regions have different anaplasmous dominant species.A.bovis has the highest infection rate in black goats and cattle in Hainan,and the co-infection of A.pagocytophilum+A.bovis is more common.The Anaplasma spp infections of black goats and cattle of different ages,genders,and rearing patterns are different.The Anaplasma spp infection rates of black goats and cattle in the free-range mode(39.7%,73.7%)are significantly higher than those of the captive mode of black goats and cattle(19.1.%,9.3%).In order to trace the origin of the pathogen,16 S r RNA gene/Gro EL gene/MSP4 gene was used to carry out PCR amplification for the anaplsmas,and the homology and phylogenetic tree were analyzed.From the 246 strains sequencing results,42 representative strains sequences were selected,and homology analysis and phylogenetic tree analysis were performed on the selected 42 strains sequences.The analysis results showed that the 9 strains of A.pagocytophilum based on the 16 Sr RNA gene showed two independent branches with the known reference sequence.Black goats and cattle clustered on different branches.The 13 strains of A.bovis based on the16 Sr RNA gene have high sequence homology,and they are all clustered on the same branch.The phylogenetic trees of 10 strains of A.ovis and 10 strains of A.marginale based on the MSP4 gene were all clustered on the same branch.The 9 strains of A.capra based on the Gro EL gene have high homology and are clustered on the same branch,and the support rate of branch nodes is as high as 100%.In this experiment,A.ovis,A.bovis,A.marginale and A.pagocytophilum have no geographical isolation and differentiation characteristics,but A.pagocytophilum has host specificity.In this study,the 16 S r RNA/Gro EL/MSP4 gene of the pathogen can be used to help trace the transmission of the pathogen.It can also be used to determine whether there are host differentiation characteristics and geographic differentiation characteristics of the anaplasma pathogen in Hainan.The information obtained from this work will be useful when carrying out treatment and prevention of anaplasmosis.