Adapted Lethality: What We Can Learn from Guinea Pig-Adapted Ebola Virus Infection Model

Table 2

Genetic changes occurring in different adaptation series and reverse genetics experiments and their relevance to the development of GPA-EBOV virulence/lethality.

Viral ORF	Nucleotide position	Amino acid substitution	Relevance to adaptation	Comment
EBOV-8mc adaptation series
NP	1852	None	No	Synonymous
	2410	None	No	Synonymous
	2411		Unlikely	Conservative, may play a supportive role in adaptation
GP	6924 (insertion)	Frameshift	No	Clones with or without those GP mutations do not differ from each other in their pathogenicity in guinea pigs
	7228		No
VP30	9595	None	No	Located in 3′-untranslated region
VP24	10557		Probably	At least, one of those three VP24 mutations induces major structural rearrangements in EBOV-8mc VP24, which are presented as gel mobility shift in electrophoresis
	10784		Probably
	10904		Probably
L	14038		Unlikely	Conservative, may play a supportive role in adaptation
EBOV-5K adaptation series
VP24	10838		No	Is acquired in the course of passage in NHPs or L68 cells, prior to adaptation
	10907		Probably	Acquired during adaptation, lies close to EBOV-8mc VP24
EBOV-GPA-P7 series
NP	1781		No	Is found in nonadapted pre-GPA clone
	2043		No	Is found in nonadapted pre-GPA clone
	2092	None	No	Synonymous
	2100	)	No	Occurred at passage 1 after pre-GPA, before the acquisition of lethality
	2164	None	No	Synonymous
	2166		Probably	Occurred at passage 3, when the first lethal outcome was recorded, heterogenous site until fixed at passage 5, concomitant with 40% lethality
	2188	None	No	Synonymous
	2191	None	No	Synonymous
	2209	None	No	Synonymous
	2222	None	No	Synonymous
	2233	None	No	Synonymous
	2260	None	No	Synonymous
	2261		No	Occurred at passage 1 after pre-GPA, before the acquisition of lethality
	2409		No	Is found in nonadapted pre-GPA clone
VP40	2456		No	Occurred at passage 1 after pre-GPA, before the acquisition of lethality
	5576	None	No	Synonymous
VP24	5597	None	No	Synonymous
	10557		Probably	Occurred at passage 6, concomitant with lethality increase to 80%
	10784		Probably	Occurred at passage 3, when the first lethal outcome was recorded, heterogenous site until fixed at passage 5, concomitant with 40% lethality
	10805		Probably	Occurred at passage 7, concomitant with full lethality
L	12286		Probably	Occurred at passage 7, concomitant with full lethality
	16821	None	No	Synonymous
Reverse genetics of EBOV-8mc mutations
VP24	10422		Definitely	Derived from the blood of an animal, which died after inoculation with a nonlethal recombinant rEBOV-NP/8mc, F648L virus. When introduced into an otherwise wild-type Zaire EBOV genome by reverse genetics, this mutation alone confers full lethality to guinea pigs