Eastern Africa Foot and Mouth Disease Virus (FMDV) Reference Antigen Panel

Background Information

This antigen panel comprises sixteen FMDV isolates that can be used to evaluate serological responses of FMDV vaccines in the context of their suitability for use in Eastern African countries. The panel is tailored to cover the genetic diversity within the FMDV lineages that circulate in Eastern African countries (namely: Burundi, Democratic Republic of Congo, Eritrea, Ethiopia, Kenya, Rwanda, Somalia, South Sudan, Tanzania, and Uganda). The following lineages are included: O/EA-2, O/EA-3, O/EA-4, A/AFRICA/G-I, A/AFRICA/G-IV, SAT1/I, SAT2/IV, and SAT2/VII. Where appropriate, isolates were also selected from neighbouring countries such as Sudan and Egypt. NB: The panel does not currently have a representative virus from the SAT1/IV topotype since the most recent example in the World Reference Laboratory for Foot and Mouth Disease (WRLFMD) collection is from 1999; this topotype has only been reported circulating in Uganda (1970-2015). Further information about the genetic diversity and circulation of these specific viruses can be retrieved from the WRLFMD website and the annual reports of the OIE/FAO FMD Laboratory Network.

Approach used to select Reference Panel Antigens

Viruses representative of contemporary lineages circulating in Eastern Africa were selected by performing phylogenetic analysis of all VP1 sequences available from WRLFMD, the OIE/FAO FMD Laboratory Network and GenBank (Figure 1).

Figure 1: Phylogenetic representation (based on VP1 sequences) of FMDV lineages circulating in Eastern Africa.  Candidate reference antigens are indicated by the coloured dots, from which the 16 reference antigens (highlighted by circles) in the Eastern Africa panel were selected. These trees also include sequences for FMD viruses from other African regions which were excluded from the selection process.

These viruses were grown in IB-RS-2 cells and initially selected for use based on their growth characteristics and viral titre. The sixteen viruses in the panel were selected to encompass the greatest extent of VP1 amino acid diversity possible. This was achieved by reconstructing phylogenetic trees from amino acid alignments of the VP1/1D region by maximum-likelihood method, and then selecting the optimal subset of evolutionary units (i.e. FMDV isolates) that maximise the phylogenetic diversity using a greedy algorithm.

Table 1: FMDV isolates in the Eastern Africa Reference Antigen Panel
Note: These FMD viruses were not selected for use as candidate FMDV vaccine strains. Organisations that require assistance to select suitable viruses for use as vaccine master seed strains should contact WRLFMD or another OIE/FAO Reference Laboratory.

 

Virus Name

Virus Lineage

1

O/KEN/4/2018

O/EA-2

2

O/ETH/4/2015

O/EA-3

3

O/ETH/9/2019

O/EA-3

4

O/ETH/14/2019

O/EA-4

5

A/ETH/2/2018

A/G-I

6

A/UGA/28/2019

A/G-I

7

A/SUD/9/2018

A/G-IV

8

A/ETH/19/2019

A/G-IV

 

Virus Name

Virus Lineage

9

SAT1/TAN/27/2012

SAT1/I

10

SAT1/TAN/22/2013

SAT1/I

11

SAT1/KEN/10/2013

SAT1/I

12

SAT1/TAN/22/2014

SAT1/I

13

SAT2/ KEN/19/2017

SAT2/IV

14

SAT2/ ETH/16/2015

SAT2/VII-Alx12

15

SAT2/EGY/1/2018

SAT2/VII-Ghb12

16

SAT2/ETH/11/2018

SAT2/VII-Lib12

Future updates to the panel

This list of reference antigens is subject to potential additions (but not subtractions) between now and 1 August 2020. Updates regarding the composition and supporting data for this panel will be made public on the following website: https://www.wrlfmd.org/au-panvac-pirbright-twinning-project/FMD-vaccine-evaluation.

Anticipated future activities include:

  1. disclosure of full capsid sequences for the sixteen reference viruses (by May 2020);
  2. antigenic profiling of selected viruses using post-vaccination and infection sera from livestock (July 2020);
  3. monoclonal antibody profiling of these viruses (in partnership with IZSLER, Brescia, Italy – TBC).

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