Table 1.

Retrovirus and retroelement mobilization in TSE

Element	Findings	References
A. Retrovirus; host species
MuLV; mouse	TSE coinfection can promote MuLV proliferation	[187, 188]
Endogenous retroviruses (ERVs); mouse	ERV sequences constituted 2 of 22 specific markers upregulated in early-stage scrapie infection	[243]
Retrovirus; elk	A retroviral insertion site was a primary diagnostic DNA sequence marker in chronic wasting disease	[244]
ERVs; macaque	BSE infection upregulates a panel of ERVs	[245]
Retrovirus; human	Retrovirus-specific sequences in infectious fractions from CJD brain but not in controls	[246, 247]
Human ERVs (HERVs)	HERV detection rates were significantly increased in CJD samples; profiles were also distinctly different: 21 of 87 sporadic CJD samples, but none of 40 controls, were dual positive for HERV types W and L	[248]
B. Retroelement; host species
Bov-tA; bovine	All infected cattle were positive for Bov-tA sequences (a short interspersed sequence mobilized by LINEs); only 5/845 healthy controls were positive	[249]
IAP-1; mouse	Scrapie infection in cultured mouse cells is associated with upregulation of IAP-1 retroelement RNA; ‘curing’ (i.e., removal of scrapie infection) of infected cells using pentosan polysulfate led to a remarkable (103-fold) downregulation of IAP-1 RNA	[250]
LINE; hamster	The most abundant scrapie-only sequence in scrapie-infected hamster brain versus controls was a LINE1 family element. Other bands were RNA 7SL (SINE parent and common partner of LINE mobilization), and target sites for LINE-family elements that insert within 18S and 28S rDNA genes	[242]
7S RNA-related sequences; hamster	Hyperabundance of 7SK-hybridizing sequences in scrapie-infected brain	[251]