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SA September 2005

Are Dromedary Camels Susceptibleor Non-Susceptible to

Foot-and-Mouth Disease Serotype O

Soren Alexandersen

Danish Institute for Food and Veterinary Research

Department of Virology, Lindholm

DK-4771 Kalvehave, Denmark

FMDWIDE HOST RANGE

Cattle, sheep, goats and pigs

African & water buffalo

Kudu, impala, warthog, deer

Some other animals, includingcamels, may possibly be infected

Man extremely seldom, mild and transient

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Are Dromedary Camels Susceptible or

Non-Susceptible to Foot-and-Mouth Disease Serotype O

Experiment 1• Virus: FMDV O UAE 542-99 (WRL O UAE 7/99) isolated in Dubai from

minor epithelial lesions from Arabian gazelles. Used as 5th BHK passage

• Animals: 2 dromedary camels and 2 heifers inoculated subepidermo-lingually with 107.6 TCID50

• Results:Heifers: Clinical disease (relatively mild), viraemia and virus detected in swabs and probangs and development of antibodies

Camels: NO clinical disease, NO viraemia, NO virus detected in swabsand probangs and NO development of antibodies

• Conclusion: no signs of infection in dromedary camels with this inoculum

Experiment 2

Inoculated

InoculatedContact

Contact

Camel Experiment 2

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Experiment 2• Virus: FMDV O UAE 542-99 (WRL 7/99) as in experiment 1, but prepared

from secondary vesicular epithelium from a heifer in experiment 1, i.e. used as 1st cattle passage

• Animals: 5 dromedary camels (3 naive and 2 from experiment 1)inoculated subepidermo-lingually with 107.8 TCID50, 5 naive dromedary camels as direct contacts and 4 sheep as contacts. Also had 2 sheep kept seperately and inoculated in the coronary band as ”positive controls”.

• Results:”Positive control sheep” : Clinical disease (relatively mild), viraemiaand development of antibodies. Typical for FMD in sheep.Contact Camels and contact sheep: NO clinical disease, NO viraemia, and NO development of antibodiesInoculated camels: NO clinical disease, but 1/3 naive camels had a one day increase in temperature and developed a viraemia and subsequently antibodies to FMDV. The 2 previously exposed camels from Exp. 1 developed antibodies to FMDV

• Conclusion: 1 out of 3 inoculated naive camels developed a viraemia but did not transmit infection to contact camels or sheep

Experiment 2 - continued

• Sequencing of virus: Sequenced nearly the complete genome (the L-fragment)

of FMDV from the serum of camel 34 at pid 3 (after a single passage in bovine thyroid cells), the inoculum from the heifer and the original 5th BKK inoculum.

The virus from the camel is identical to the input virus from the heifer.

Interestingly, this virus (from the heifer and from camel 34) is slightly different

from the original inoculum, i.e. the 5th BHK passage.

The original 5th BHK passage had 8 sequence differences in the L fragment when compared to the two in vivo viruses. Of the 8 differences, 3 were non-coding

(2 differences in 2C and 1 difference in 3D).

Of the 5 coding differences, 1 is in VP-3 (aa # 158 proline to serine); 2 differences are in VP-1 (aa #13 alanine to threonine and aa # 144 alanine to valine); and 2

differences in 3A at amino acid # 104 (glycine to asparagine) and #129 (alanine to threonine).

May potentially have to do with BHK cell culture and subsequent in vivo adaptation

as the VP-3 change may reflect on heparan sulphate binding, the VP-1 changes(in particular at aa# 144 just before the RGD motif) may change receptor interaction

and the 3A changes may also have to do with adaptation to host cells.

Daily Temperature of FMD treated and control camels

34,0

34,5

35,0

35,5

36,0

36,5

37,0

37,5

38,0

38,5

39,0

-10 -5 0 5 10 15 20 25 30

Days PI

Tem

per

ature

Camel 26 (Control)

Camel 27 (Control)

Camel 28 (Control)

Camel 29 (Control)

Camel 31 (Control)

Camel 30 (Treated)

Camel 32 (Treated)

Camel 33 (Treated)

Camel 34 (Treated)

Camel 35 (Treated)

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Camel Exp. 2 Viraemia

0

1

2

3

4

5

6

7

8

9

0 1 2 3 4 5 6 10 14 21 28

Days

Lo

g10 v

iru

s o

r R

NA

per

ml

532v

537v

34v

532r

537r

34r

Dect. lim. V

Dect. lim. R

Camel Exp. 2 Antibodies

0

100

200

300

400

500

600

700

0 1 2 3 4 5 6 10 14 21 28

Days

Tit

re

532ae

537ae

34ae

30ae

33ae

532av

537av

34av

30av

33av

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Future experiments

• As experiment 2 has indicated that FMDV serotype O under certain

circumstances infect camels (caused viraemia, antibodies and elevated

body temperature in 1 out of 3 camels) when using a fully virulent serotype

O isolate, it may also be worthwhile to continue these experiments to get better statistical data.

Next use 10 naive camels directly inoculated with the heifer 144 type

O inoculum - have no contact camels as experiment 2 indicated that

contact spread is of no significance.

• Continue the experiments using FMDV serotype A as this is the other

serotype that has been found in the area in or around UAE.An isolate from the region (A SAU 22/92 original epi suspension) from

infected cattle material has been agreed upon among Ulli Wernery, Soren

Alexandersen and Nigel Ferris/David Paton at the FMD-WRL in Pirbright.

• Clearly, the preliminary results from experiment 2 suggest that there is

much more experimental work to do in order to conclude on the relative,

but low, susceptibility of dromedary camels to infection with FMDV.

Camel Exp. 2 Antibodies

0

5

10

15

20

25

30

35

40

45

0 1 2 3 4 5 6 10 14 21 28

Days

Tit

re

34ae

30ae

33ae

34av

30av

33av

Dect. lim. (50%)

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Thanks to Ulli Wernery, Renate Wernery, Peter Nagy, Jutka Juhasz, Anita Varga and Winni Schiele at

CVRL, Dubai, colleagues and staff at

Pirbright Laboratory and at DFVF-Lindholm, and

Gitte Alexandersen, Barup, Denmark

Research supported by DFVF as well as by

HH General Sheikh Mohammed Bin Rashid Al Maktoum

THE END

SUMMARYExperiment 1

5th BHK passage FMDV O UAE 7/99 inoculum

2 dromedary camels and 2 heifers inoculated in the tongue with 107.6 TCID50

Heifers: Clinical disease (relatively mild) and virus and antibody detected

Camels: NO clinical disease, NO viraemia, NO virus detected and NO

development of antibodies

Conclusion: no signs of infection in dromedary camels with this inoculum

SUMMARYExperiment 2FMDV O 7/99 as in experiment 1, but prepared from secondary vesicular epithelium from heifer in experiment 1, i.e. used as 1st cattle passage

5 dromedary camels (3 naive and 2 from experiment 1) inoculated in the tongue with 107.8 TCID50, 5 naive dromedary camels and 4 sheep as contacts.2 inoculated sheep kept seperately (”positive controls” got typical disease, viraemia and development of antibodies).

Contact Camels and contact sheep: NO clinical disease, NO viraemia, and NO development of antibodies

Inoculated camels: NO clinical disease, but 1/3 naive camels had a one day increase in temperature and developed a viraemia and antibodies. The 2 previously exposed camels from Exp. 1 developed antibodies

Original 5th BHK virus had 8 sequence differences in the L fragment compared to the two in vivo viruses. Of 8 differences, 5 were coding differences; 1 in VP-3; 2 in VP-1 and 2 differences in 3A.

Conclusion: 1 out of 3 inoculated naive camels developed a viraemia but did not transmit infection to contact camels or sheep