FOOT AND MOUTH DISEASE VIRUS EXPRESSING CHIMERIC CAPSID 

PROTEIN: A TOOL FOR DELINEATION OF NEW ANTIGENIC SITES AND VACCINE 

STRAIN SELECTION

Jitendra Kumar BiswalScientist

ICAR‐Directorate of FMD, Mukteswar, India

Overview

• Global distribution of FMDV serotype A andrecent spread of Genotype VII (18)

• Lack of suitable vaccine strain against currentgenotype VII (18)

• Chimeric FMDV and evidences that the VP2capsid protein has been responsible for theantigenic un‐relatedness of the recent genotype‐18

• Identification new putative antigenic epitope(VP2‐74) and its role for antigenic un‐relatedness.

Global Distribution of Serotype A

Genotype VII (18)As, E (1984‐2010)Indian subcontinent

Genotype IV (10)As, E (1964‐1990)Middle East, South, Central & Northern Asia

Genotype III (4)As (1958‐1964)China

Genotype IX (20)As (1987‐2010)South‐East & East Asia

Genotype VI (16)As (1982‐2001) India

Genotype VIII (19)As (1987‐1991)Middle East

Genotype 25As (2002‐2007)Middle East

Genotype 26(A IRN‐05)As (2001‐2008)Middle East

Genotype 8As (1960)Thailand

Genotype 9Af (1964‐1974)East & North AfricaGenotype 15(Af (1977‐2006)East & West Africa

Genotype 23Af (1997‐1998)North‐West Africa

Genotype 11Af (1965)KenyaGenotype 1

E (1929)Germany

Genotype 5SA (1958‐1967)Northern South America

Genotype I (2)E, SA, As, Af (1932‐1989)

Genotype 12SA (1966‐1971)Argentina

Genotype 13SA (1968‐2002)Southern South America

0.02 nucleotide substitution/site

ASIA Topotype

AFRICA Topotype

EURO‐SOUTH AMERICATopotype

76

100

99

9999

100

100

91

99

100

99

9968

10071

87 1001008496

95

8263

62

Genotype 18 (VII)• Since 2001, genotype VII (18) has been exclusively

responsible for all the field outbreaks

• Within the genotype-18 a divergent and unique lineage emerged in late part of 2002, which showed an amino acid (aa) deletion at 59th position of VP3 (VP359-deletion group). From 2007–2008, there is an upsurge in incidence of outbreaks due to this lineage.

• In 2015, it appeared for the 1st time in the Middle East, during the same year, by Iran, Turkey and Armenia. Most recently (May 2017), this virus was identified in Northern Israel, on the Lebanese and Syrian borders, Nepal and Bhutan.

Antigenic relatedness• Currently, majority of the field isolates belonging

to the VP359-deletion group were foundantigenically unrelated to the in-use vaccinestrain through the 2D-VNT assay.

• Considering the antigenic diversity, a panel of 3candidate vaccine strains were selected, and onestrain provided good antigenic coverage (79 outof 84 tested isolates were matched).

• Sequence analysis in the countrywidelongitudinal data-set could not determine anyspecific fixation of amino acid substitution at theknown antigenically critical positions.

VP4 VP2 VP3 VP1

VP4 VP2 VP3 VP1VP3

VP4 VP2 VP3 VP1VP2

VP4 VP2 VP3 VP1VP4

Chimeric infectious clones were generated through Mega‐primer mediated domain swapping method (Biswal et al., 2015)

VP4 VP2 VP3 VP1 VP4 VP2 VP3 VP1

A IND 40/2000 A PD 26/2015

Domain Swapping Mutagenesis and chimericcDNA clones 

2D‐VNT with A IND 40/2000 BVS

00.10.20.30.40.50.60.70.80.9

1

r1‐Value

s

VP4 VP2 VP3 VP1VP2

1 146 218

VP4 VP3 VP1

VP4 VP3 VP1

Chimeric VP2

Chimeric VP2

A IND 40/2000A PD 26/2015

Chimeric‐VP2 cDNA clones 

00.10.20.30.40.50.60.70.80.91

40/2000 40/2000‐Chi‐VP2 (1‐146)

40/2000‐Chi‐VP2 (146‐218)

r1 Value

s

2D‐VNT with A IND 40/2000 BVS

Position and Amino Acid

Secondary Structure

Entropy Values

ConsurfValues

Consensus between genetic and antigenic variants

55-V/K/E/L/N/T αZ helix 0.403 -0.340 Not found74 -A/P/S βC–βC loop 0.798 3.033 Yes (A→P)

79-E/V/G/A/Q βC strand 0.505 2.533 No96 -D/G/N/K/E αA helix 0.510 0.332 Not found

131-E/K/D/G/H/N βE–βF loop 1.064 1.734 Not found

Putative antigenic residue(s) on the VP2‐protein of the antigenic variants  

VP2‐72

VP2‐74

VP2‐131

Reduction in Virus neutralization titre and associated ‘r1’‐value after site‐directed 

mutagenesis

0

20

40

60

80

100

A 40/2000 A 40/2000-A2074P

A 40/2000-A2074S

A 40/2000-K2131E

Red

uct

ion

in V

N ti

tre

(%)

2D-VNT was carried out using BVS against A IND 40/2000

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

A 40/2000 A 40/2000-A2074P

A 40/2000-A2074S

A 40/2000-K2131E

r1-V

alue

s

A B

r1‐values of serotype‐A field isolates with Rabbit anti‐146S serum 

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

A 40/2000-Chi-VP2 A 40/2000

r1-v

alue

sof

fiel

d is

olat

es

18/20 1/20

Conclusions

• Reverse genetics technology based chimericFMDV is a handy tool for the determination ofthe role of individual capsid protein(s) in theviral‐antigenicity .

• New antigenic epitope (VP2‐74) was identifiedon the capsid surface of FMDV serotype A‐genotype VII(18).

ACKNOWLEDGEMENTS • GFRA Executive Committee• Technical and Scientific Staffs of

ICAR- Directorate of FMD, Mukteswar, India