. 2018 Jun 12;10(6):320. doi: 10.3390/v10060320

Table 3.

Spontaneous mutations in different EV-A71 subgenotypes (BrCr, B1-B5, C1-C5).

Mutant Strains of EV-A71	Significance of the Mutations in the EV-A71 Genome	References
Analysis of EV-A71 subgenotype C4 showed changes in the 5′-NTR and the VP1.	When the nucleotide cytosine was substituted with uridine at position 158, the conformation of the RNA secondary structure of stem loop II in the 5′-NTR changed, leading to a decrease in viral translation and virulence in mice.	[38]
Nucleotide and amino acid changes in neuro-virulent strains of EV-A71 subgenotype C4a.	These amino acids are potential molecular determinants of virulence. Variations in the secondary structure of the 5′-NTR at three positions (C^P241/T^P241, A^P571/T^P571 and C^P579/T^P579) and one position in the 3′-NTR(T^P7335/C^P7335) might confer fatality.	[39]
Comparisons of EV-A71 across different genotypes (BrCr, B1-B5 and C1-C5)	These amino acid residues might be associated with the EV-A71 virulentphenotype.	[40]
Changes in VP1 sequences of EV-A71 subgenotype C4 causing severe HFMD	E145Q/G interacts with residues of the PSGL-1 N-terminus and acts as a molecular switch to modulate binding to the cell receptor by controlling the exposure of the amino acid (VP1-244K) on the VP1 surface.	[41,42]
Analysis of EV-A71 subgenotype C4 showed changes in the 5′-NTR and the VP1	K215A located at the VP1 GH loop increased the thermal stability of the virus.	[44]
Roles of K244E and H37R were investigated by reverse engineering in the EV71-B2 isolate, MS/7423/87	It was postulated that H37E and K244E interactions were important for replication in primate cells but K244E alone was able to confer the ability of the virus to replicate alone in a murine model	[45]
Role of K²¹⁶→R, G¹⁴⁵→E and K¹²⁹→I in the mouse-adapted strain of EV-A71 26M/AUS/4/99	G¹⁴⁵→E mutation was solely responsible for an increase in virulence in mice whilst K¹²⁹→I led to an improved growth of the strain in vitro but did not lead to increased virulence in mice	[48]
Analysis of the genomes of six EV-A71 strains of subgenotype C4a identified the only change of amino acid Asn 1617 in the 3C gene	This specific amino acid led to conformational change at the active centre of the 3C proteinase (3C^pro) and this could be a potential molecular determinant for the EV-A71.	[49]

Analysis of different EV-A71 strains showing the position of the spontaneous mutations present in the genomes of EV-A71 and their significant impact on virulence.