Table 2.

Comparative studies of EV-A71 genome sequences and their phenotypic differences.

	Phenotypic Differences
Mutations	In vitro	In vivo	References
Protease 2A from a severe strain → protease 2A from a mild strain Protease 2A Position 64 (Y64H) Position 68 (M68R) Position 85 (D85E)	RD cells, Vero cells and SH-SY5Y cells ➢Slower replication compared to the severe strain at 37 °C and 39.5 °C ➢Less viral RNA compared to the severe strain at 37 °C and 39.5 °C	1-day-old ICR mice ➢Less severe pathological changes compared to severe strain ➢Lower viral load compared to severe strain	[78]
3CD region from severe strain → 3CD region from mild strain Protease 3C Position 138 (V138I) 3D polymerase Position 37 (S37N) Position 143 (R143K) Position 176 (I176V) Position 261 (E261G) Position 360 (G360A)	RD cells and Vero cells ➢Milder CPE as compared to severe strain at 37 °C and 39.5 °C ➢Decreased replication rate compared to severe strain at 39.5 °C	1-day-old ICR mice ➢Mice showed no paralysis, no death, less body weight loss, and milder symptoms as compared to the mice injected with the severe strain ➢Lower viral load as compared to mice infected with the severe strain	[38]
Weakly pathogenic strain → Highly pathogenic strain 5’ UTR Position 115 (115C>T) Position 132 (132T>C) Position 811 (811T>C) VP1 Position 639 (G639S) VP3 Position 485 (Q485R) Position 504 (A504V) Position 537 (V537I) Protease 2A Position 937 (G937S) Protease 2B Position 1014 (A1014V) Position 1045 (I1045V) Position 1062 (T1062I) Protease 2C Position 1135 (K1135R) Position 1145 (E1145D) Position 1155 (V1155A) Position 1361 (V1361M) Protease 3C Position 1597 (I1597V) Position 1617 (D1617N) 3D Polymerase Position 1746 (L1746F) Position 2146 (A2146V) 3’ UTR Position 7347 (7347A>G)	Nucleotide differences when a weakly pathogenic strain (JN200803) is compared to a highly pathogenic strain (JN200804) MA104 cells ➢Both strains (weakly and highly pathogenic strain) exhibited similar CPE ➢No difference in virulence as determined by TCID50 titration	1-day-old BALB/c mice ➢Mice infected with the highly pathogenic strain exhibited hind limb paralysis by day 4 post-infection. ➢Mice infected with the weakly pathogenic strain had no evident neurological symptoms and remained healthy.	[79]