Two novel amino acid substitutions in highly conserved regions of prion protein (PrP) and a high frequency of a scrapie protective variant in native Ethiopian goats.

BACKGROUND: Polymorphisms of the prion protein gene may influence scrapie susceptibility in small ruminants through modified protein conformation. At least 47 amino acid substitutions and 19 silent polymorphisms have been described in goat PRNP reported from several countries. The objective of this study was to investigate PRNP polymorphisms of native Ethiopian goat breeds and compare the results with other goat breeds. RESULTS: The analysis of the prion protein gene PRNP in 229 goats belonging to three of the main Ethiopian native goat breeds showed a remarkably high frequency (> 34.6%) of p.(Asn146Ser) in these breeds, a variant involved in scrapie resistance in Cyprus. In addition, two novel amino-acid substitutions p.(Gly127Ala) and p.(Thr193Ile), with frequencies ranging from 1.5 to 7.3% were detected. Both amino acids are well conserved in prion proteins (PrP) of most species and these changes have never been reported before in goats worldwide. Residue 127 is within the N-terminal domain of PrP and is probably involved in the recruitment of neural cell adhesion molecules (NCAM). Residue 193 is within the highly conserved string of 4 threonines that plays a role in determining the efficiency of prion protein conversion towards its pathological form. CONCLUSION: Two novel coding polymorphisms and a high frequency of a scrapie protective variant indicate a high level of genetic diversity in PRNP of Ethiopian goats. This finding increases the interest in exploring PRNP polymorphisms of native goat breeds in areas where cross breeding with foreign goats has rarely occurred.

Seroprevalence and Risk Factors of Toxoplasma gondii Infection among Domestic Ruminants in East Hararghe Zone of Oromia Region, Ethiopia.

A cross-sectional study was carried out from July 2011 to September 2013 to assess the seroprevalence and identify risk factors of Toxoplasma gondii infection in domestic ruminants of East Hararghe zone of Oromia region, Ethiopia. Sera of 1360 domestic ruminants were analyzed for the presence of anti-T. gondii IgG antibodies using the indirect enzyme-linked immunosorbent assay (iELISA). Additionally, the owners were also interviewed using a structured questionnaire to identify the potential risk factors of T. gondii infection. Overall, the prevalence of T. gondii infection in domestic ruminants was 22.2% (302/1360). The seroprevalence in sheep, goats, cattle, and camels was 33.7%, 27.6%, 10.7%, and 14.4%, respectively. District, species, sex, age, and water source were identified as risk factors for T. gondii infection. Increased seropositivity was observed in females (OR = 2.63) and also with the use of pond (OR = 4.25) and pipe (OR = 9.57) water sources in sheep; age >1 year old (OR = 3.45) and with drinking from pond (OR = 6.03) and pipe (OR = 11.61) water sources in goats; with the use of pond (OR = 5.60) and pipe (OR = 10.68) water sources in cattle; and in >4-year-old camels (OR = 2.49). In conclusion, T. gondii infection is common and widespread among the domestic ruminants of the study area, indicating the potential transmission to humans from these animals when they are used as a source of food. Hence, it is crucial to raise awareness of the people about T. gondii infection and conduct further study to explore the impact of the disease on food animal production.