Rift Valley Fever Seroconversion

Friday, 5th May 2017

Sero-conversion in Angora goats following vaccination by  OBP RVF vaccines

 

There was rightly concern expressed amongst producers as to whether the OBP vaccine was in fact causing seroconversion?

In 2011 a study by Cape Wools SA found that 67.6% of sheep vaccinated failed to seroconvert 14 days after vaccination with the live RVF (Smithburn) vaccine (batch 111) with all remaining animals showing antibody titres no greater than 1:10 ( Cape Wools SA Study: Sero-conversion in sheep following vaccination by Smithburn and Clone 13 Rift Valley Fever vaccines).

 

Thanks to Richie Herold of Ordonnantsie ,Graaff-Reinet, for arranging the goats and assisting with the study.

 

Method:

 

OBP Rift Valley Fever Vaccine Batch 123 Exp 1/11/2017 was purchased from the Graaff-Reinet CMW/OVK and cold chain protocols followed as per manufacturer’s instructions.

10 Angora goat ewes were used in the study.

 

  • Blood samples were taken prior to vaccination on the 10th January 2017.
  • The goats marked and were vaccinated with the OBP RVF vaccine.
  • Blood samples (prior to vaccination) were couriered to OVI to test for antibodies against RVF.(IgG-I-Elisa).
  • 3 weeks later, on the 31st January, blood samples were again taken from the 10 goats.
  • These samples were sent to OVI for seroconversion after vaccinating.

 

Results:

Angora goat ID

IgG levels

Prior Vaccination

IgG levels 21 days Post Vaccination

1

0

31

2

0

83

3

0

133

4

0

99

5

0

100

6

0

82

7

0

88

8

0

100

9

0

81

10

0

122

Average

0

92

 

Discussion:

 

Comparing these results with trials done in the past to determine seroconversion ( Paweska et al 2005) (Van Vuren et al 2006) and (Paweska et al in 2003).

 

The SAMGA field study results were superimposed (in RED ) on the graph by Paweska

 

 

. Mean±S.D. immunological responses in sheep  (n = 10) vaccinated with liveattenuated

Smithburn strain of Rift Valley fever virus.

 

 

CONCLUSION:

 

The OBP RVF (Smithburn) Batch 123 showed good comparable seroconversion in Angora goats vaccinated in this field study.

 

Dr Mackie Hobson (SAMGA Vet)

 

LITERATURE CITED

Janusz T Paweska, Elizabeth Mortimer, Patricia A. Leman, Robert Swanepoel 2005

An inhibition enzyme-linked immunosorbent assay for the detection of antibody to Rift Valley fever virus in humans, domestic and wild ruminants

 

Paweska, J.T., Burt, F.J., Anthony, F., Smith, S.J., Grobebellaar, A.A., Croft, J.E., Ksiazek, T.G., and Swanepoel, R. 2003

IgG-sandwich and IgM capture enzyme-linked immunosorbent assay for the detection of antibodies to Rift Valley fever virus in domestic ruminants.

 

Petrus Jansen van Vuren, Abraham C. Potgieter, Janusz T. Paweska, Alberdina A. van Dijk. 2006

Preparation and evaluation of a recombinant Rift Valley fever virus N protein for the detection of IgG and IgM antibodies in humans and animals by indirect ELISA

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