All mammals have prion proteins as the following table shows:

Disease abbreviation	Natural host	Prion	Abnormal PrP Term	Alternate PrP Term
scrapie	sheep & goats	Scrapie	ShePrPSc	ShePrPSc"
transmissible mink prionencephalopathy (TME)	mink	TME	MkPrPSc	MkPrPScTME
chronic wasting disease (CWD)	mule deer & elk	CWD prion	MDePrPSc	MDePrPCWD
bovine spongiform encephalopathy (BSE)	cattle	BSE prion	BovPrPSc	BovPrPBSE
feline spongiform encephalopathy (FSE)	cats	FSE prion	FePrPSc	FePrPFSE
exotic ungulate encephalopathy (EUE)	nyala & greater kudu	EUE prion	NyaPrPSc	NyaPrPEUE
kuru	humans	Kuru prion	HuPrPSc	HuPrPKu
Creutzfeldt-Jakob disease (CJD)	humans	CJD prion	HuPrPSc	HuPrPCJD
Gerstmann-Straussler-Scheinker syndrome (GSS)	humans	GSS prion	HuPrPSc	HuPrPGSS
fatal familial insomnia (FFI)	humans	FFI prion	HuPrPSc	HuPrPFFI

As can be seen from the following diagram, comparing a mouse and a hamster prion, prions from different species are very similar to each other.

The experience of kuru and CJD transmitted via human growth hormone injections demonstrates how it is possible for one human being to be infected by another human being. Although, the actual infection process is still a matter for research.

For one of the central hypotheses of BSE transmission to humans to be true, it is necessary for animal prions, particularly bovine ones, to have the same or similar effect to human ones.