Molecular epidemiology and point mutations in ITS1 and 18S rDNA genes of Eimeria ninakohlyakimovae and E. christenseni isolated from Indian goats

Abstract

Epidemiology and molecular characterization of Eimeria was carried in goats reared under semi-arid region of west Uttar Pradesh, India. A total of 1285 faecal samples from different goat breeds (Jamunapari, Jakhrana and Barbari) were examined for presence of Eimerian oocysts over a period of eight months along with faecal oocysts count. All raw data of faecal oocyst counts (FOC) were transformed by loge (OPG+ 100) before analysis. All fixed effects like breed, age, months of sample collections along with their interaction were considered in analysis. The overall prevalence of Eimeria infection in goats was 73.85%. Breed wise prevalence in Barbari, Jamunapari and Jakhrana breed was 68.62, 79.70 and 72% respectively. Prevalence observed in 2-6M, 6-12M and >12M was as 70.83, 79.88 and 71.74% respectively. Gender wise prevalence as observed in male and female goats was 71.95 and 74.43% respectively. In oocyst per gram (OPG) data analysis the fixed effects like breed, age, months of sample collection and age versus gender interaction had significant effect on log transformed faecal oocysts counts (LFOC). The overall least square means of OPG was 4.673±0.007 (1403OPG). Of the three goat breeds, Jamunapari had highest OPG (2886OPG) compared to Jakhrana (875OPG) and Barbari (523OPG). Mean OPG in 2-6month age goats was significantly higher than the corresponding values in 6-12 and >12months, significant variation was found among monthly OPG means and wet months showed higher faecal oocysts discharge. Nine Eimeria species were identified infecting goats and E. arloingi and E. ninakohlyakimovae were most frequent and predominant species. Molecular characterization for coccidial infection was conducted using two genes i.e. 18S rDNA and ITS-1 genes which amplified 637bp and <500bp (E. ninakohlyakimovae) and >500bp (E. christenseni and E. alijevi) respectively. The ITS1 gene was analysed by sequencing, E. christenseni was found showing nucleotide similarity with E. bovis and E. ellipsoidalis whereas 3' end of the sequence were highly conserved. The ITS1 gene of E. ninakohlyakimovae was found more homologous to E. bovis, E. ellipsoidalis and E. zuernii but for 33rd nucleotide thymidine residue deletion and 5th position G→A mutation. The 18S rDNA sequences of E. ninakohlyakimovae and E. christenseni were studied for evolutionary divergence analysis and maximum divergence was noticed between E. ninakohlyakimovae and E. christenseni (0.0605). The phylogenetic tree showed E. ninakohlyakimovae was placed in same clade with other Eimeria spp. compared, but E. christenseni being placed in a different clade as an out-group.