| Haemonchus contortus is the predominant hematophagous gastrointestinal nematode affecting the goat production and causes significant economic losses in the humid,tropical and subtropical region like China and Bangladesh.As a control strategy,besides the use of anthelmintic,select the resistance goat breeds with background history,identify resistance genes and gene variants(SNPs)which are involved in the immune response against GI nematode infection might be an effective alternative method for responding against effects of H.contortus infection.The current study investigated the prevalence of GI parasite for only Bangladeshi population and evaluated resistance and susceptibility to H.contortus infection in different goat breeds/populations in China and Bangladesh under the natural grazing condition and identified genetic resistant candidate genes with their Single nucleotide polymorphisms(SNPs)that are associated with Fecal Egg count trait.1.A total of 897 Black Bengal goats for three consecutive years were examined to investigate the prevalence rate of gastrointestinal(GI)parasite especially for H.contortus infection in Bangladesh.Among the GI parasites,the highest prevalence(55.2%)was found for Eimeria oocyst as well as the highest FEC(1678.53±154.62epg).The lowest prevalence(7.6%)was observed for Moniezia spp.FEC significantly differed between sexes(P<0.01)and among population groups and years(P<0.001),respectively.Among the gastrointestinal nematodes,the highest prevalence was found for H.contortus(47.1%)with the highest FEC 355.09±18.54epg.Significance differences(P<0.05)was observed among the different goat populations whereas Black Bengal High Low land goat(BBHL)showed the highest prevalence(76.1%)with the highest FEC(2354.55±119.26epg)whereas,Black Bengal High Hilly(BBHH)goats showed a lower prevalence(33.3%)with lower FEC(220.00±12.31epg)than other goat populations that are indicating BBHH goat population is less susceptible to H.contortus infection.2.The susceptibility of H.contortus infection of 430 goats in six goat breeds/populations were investigated from China and Bangladesh under the natural grazing condition by FEC.The average FEC in Chinese and Bangladeshi goats were 402.86+46.60epg,and 158.00+31.30epg,respectively and infection rate of H.contortus was 68.21%and 58.00%,respectively.The highest prevalence of H.contortus infection was found in Enshi Black(88.89%),and the highest parasitic load was found in Chinese hybrid(527.74+78.13epg)goat population.The lowest prevalence of parasite infection was observed for Black Bengal western(BBW)(53.10%)and the most moderate parasitic load was found in Black Bengal Hilly(BBH)(112.16+17.37epg)goat population among all goat breed/population.FEC differed significantly(P<0.01)among goat populations in China and Bangladesh.BBH goat in the hilly region of Bangladesh is less susceptible to H.contortus infection in term of FEC among all goat populations under natural grazing condition.3.A total of 507 goats from China and Bangladesh were examine on the basis of FEC and total 129 polymorphisms from 84 different candidate genes that were involved in immune system in which ten polymorphisms(SNPs)in six genes(CIITA,ATP2A3,HSPA8,STAT5B,ESYT1,and SERPING1)had significant associations with FEC at a nominal significance level of P<0.05.Two missense mutations located in the exon region of the caprine CIITA gene.Chinese goat breeds had significantly higher FEC than that in Bangladeshi goat breeds within their respective genotypes.Genetic parameters such polymorphism information content(PIC),effective allele number(Ne),and heterozygosity(He)were highest for STAT5B?197?A>G and highest for YCW goats(0.50,2.00,and 0.38,respectively)followed by CCB,BBG,ESB,and NJY goats.The lowest values for He,Ne,and PIC were observed for CIITA in all goat breeds.Pairwise coefficients of linkage disequilibrium revealed complete LD between significant SNP in CIITA and SERPING1 and strong LD between polymorphisms in HSPA8 and ATP2A3,respectively.Correlation coefficients between PCV and FEC were negative and significantly differed(r=-0.47;P<0.001)but the correlation between PCV and BW was non-significant in all goats.The correlation between BW and FEC was highly significant and positive(r=0.56;P<0.001).Association analysis revealed that haplotypes within ATP2A3,HSPA8,and SERPING1were significantly associated with FEC.4.A total of 46 SNPs from 12 candidate genes related to the regulation of innate immune signaling were found,in which eleven polymorphisms in four genes(NLRC3,NLRC5,HIP1 and LRP8)were associated with FEC at a nominal significance level of P<0.05.Three missense mutations were identified in coding regions in NLRC5 and HIP1.Genetic parameters such as the polymorphism information content(PIC),gene heterozygosity(He)and effective allele number (Ne)were greatest for the HIP1?1077?A>G gene locus in all goat breeds except the Nanjing Yellow and Enshi Blacks from China.Pairwise coefficients of linkage disequilibrium(D',r~2)revealed strong linkage disequilibrium among significant SNP in LRP8(r~2=1 to 0.87)and between polymorphisms in NLRC3,NLRC5 and HIP1(r~2=0.96 to 0.99).Association analysis revealed that haplotypes within NLRC3,NLRC5 and HIP1 were associated(P<0.001)with FEC.5.The resistance or susceptibility of goat individual to GI nematode infection was estimated based on low and high responder of FEC of Yichang White Goat(YWGs).The FEC,circular blood parameter such as hemoglobin levels(Hg)and PCV was determined for selected animals and prepared for artificial challenge trial.The mean of FEC for a resistant group of goats was103.38±1.20 epg whereas,in susceptible goats with the mean 1180.25±43.53 epg and show significant differences.The mean Hemoglobin(Hg)and pack cell volume(PCV)was significantly different(p<0.01)between the resistant and susceptible group and during the trial period and gradually declined and FEC was higher in a susceptible group than the resistance group.The relative m RNA expression was investigated by using q RT-PCR for ATP2A3,SERPING1,CIITA,HSPA8,ESYT1,STAT5B,NLRC3,NLRC5,HIP1 and LRP8 candidate gene in YHG goat that is resistant to H.contortus infection.Quantitative real-time PCR revealed that the expression level of m RNA for ATP2A3(P<0.00001),HSP8A,ESYT1 and SERPING1(p<0.001),HIP1 and LRP8(P<0.0001)is higher in resistant goat compared to susceptible goat,except NLRC5(P<0.0001),in susceptible goat,was significantly higher compared to resistance goats. |
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