A pioneering genetic study has identified key variations in the prion protein gene (PRNP) that could influence resistance to prion diseases in Nigerian livestock species. The research, led by Dr. Adeniyi Charles Adeola of the Kunming Institute of Zoology, Chinese Academy of Sciences, provides crucial insights into the genetic factors that could protect animals from these fatal neurodegenerative disorders.

Speaking on the study, Dr. Adeola highlighted the significance of this research for livestock health. “Prion diseases, also known as transmissible spongiform encephalopathies (TSEs), are a major threat to both wild and domesticated animals. Understanding genetic variations in PRNP could help us identify animals that are naturally resistant to these diseases, which is vital for disease control and breeding programs,” he explained.

Prion diseases, including scrapie in sheep and chronic wasting disease in deer, result from the accumulation of misfolded prion proteins (PrPSc) in the brain, causing severe neurological deterioration. The PRNP gene encodes normal cellular prion proteins (PrPC), and mutations in this gene can determine susceptibility or resistance to infection.

To explore these genetic variations, the research team analyzed PRNP sequences from five Nigerian livestock species—camels, dogs, horses, sheep, and goats. Blood samples were collected from 65 camels, 31 village dogs, and 12 horses across seven Nigerian states. Additional data from 126 sheep and 132 goats, as well as PRNP sequences from other mammalian species, were retrieved from genomic databases for comparative analysis.

The study identified 162 unique haplotypes across the 994 sampled individuals, with sheep exhibiting the highest genetic diversity (54 haplotypes) and camels the lowest (7 haplotypes). Phylogenetic analysis confirmed that Nigerian livestock species clustered distinctly within their respective groups, reinforcing the genetic uniqueness of these populations.

A key finding of the study was the detection of five non-synonymous single nucleotide polymorphisms (SNPs)—G9A, G10A, C11G, G12C, and T669C—shared by all Nigerian livestock species. These SNPs were in Hardy-Weinberg equilibrium, suggesting they are stable genetic traits in the population. “The amino acid changes associated with these SNPs were all predicted to be ‘benign’ by the PolyPhen-2 program, meaning they do not negatively impact protein function,” Dr. Adeola noted.

The research also uncovered species-specific SNPs. For instance, three SNPs (G34C, T699C, and C738G) were unique to Nigerian dogs, while four others (C16G, G502A, G503A, and C681A) were found only in Nigerian horses. Additionally, one SNP (C50T) was detected exclusively in Nigerian sheep and goats.

According to Dr. Adeola, these findings have far-reaching implications. “The identification of these genetic variants provides a foundation for further studies on prion disease resistance. With additional research, we can explore whether certain SNPs contribute to natural immunity against prion diseases in livestock,” he said.

The study also underscores the importance of genetic diversity in disease resistance. “Sheep displayed the highest number of haplotypes in our study, which could suggest a greater potential for genetic resilience. This supports the idea that preserving diverse livestock populations is key to maintaining disease resistance in the long term,” Dr. Adeola added.

Future research will expand on these findings by incorporating a larger sample size, analyzing different coat colors, and investigating the functional impact of PRNP variations on disease susceptibility. Researchers also plan to examine the prevalence of prion diseases in Nigerian livestock and explore potential breeding strategies for disease-resistant animals.

This study, titled “Single nucleotide polymorphisms (SNPs) in the open reading frame (ORF) of prion protein gene (PRNP) in Nigerian livestock species,” was published in BMC Genomics on February 14, 2024. The project was financially supported by the Sino-Africa Joint Research Center, the Chinese Academy of Sciences, and the Chinese Academy of Sciences President’s International Fellowship Initiative.

Dr. Adeola emphasized the broader impact of this research, stating, “By understanding the genetic mechanisms behind disease resistance, we can take proactive steps to protect livestock populations, improve food security, and strengthen animal health programs across Nigeria and beyond.”