Marker system, in particular for baculovirus-expressed subunit antigens

1. A method of differentiating a non-vaccinated mammal or bird from a mammal or bird which has received an immunogenic composition comprising the steps of:

a. obtaining a biological sample from a mammal or bird;

b. contacting antibodies of the biological sample with a capture reagent, wherein the capture reagent specifically binds antibodies specific for a rhabdovirus antigen and is selected from:

i. a polypeptide comprising a sequence having at least 95% sequence identity with any one of SEQ ID NOs: 1 to 8;

ii. a RNA virus which comprises a polypeptide comprising an amino acid sequence having at least 95% sequence identity with the sequence of SEQ ID NO: 1 and/or SEQ ID NO: 7; and

iii. a synthetic polypeptide having a sequence selected from the sequences consisting of 5 to 11 consecutive amino residues of SEQ ID NO: 1 or SEQ ID NO: 7; and

c. detecting for the presence of capture reagent-antibody complexes,

wherein the presence of capture reagent-antibody complexes indicates that said mammal or bird has received said immunogenic composition, and thus differentiates a vaccinated mammal or bird from a non-vaccinated mammal or bird.

2. The method of claim 1 , wherein the capture reagent is immobilized to a solid support.

3. The method of claim 2 , wherein the immobilized capture reagent is coated on a microtiter plate.

4. The method of claim 1 , wherein said capture reagent is said RNA virus, and wherein said RNA virus is a (-)ssRNA virus which belongs to the family Rhabdoviridiae and/or is capable infecting insect cells.

5. The method of claim 4 , wherein said RNA virus is capable of infecting insect cells.

6. The method of claim 4 , wherein said RNA virus is capable of infecting Spodoptera Frugiperda (Sf) cells or cells derived from Spodoptera Frugiperda.

7. The method of claim 6 , wherein said RNA virus is capable of infecting Sf9 cells and/or Sf+ cells.

8. The method of claim 1 , wherein the detecting step (c) comprises:

a. contacting capture reagent-antibody complexes with a detectable agent that binds to the antibody of the capture reagent-antibody complex;

b. measuring the level of antibody bound to the capture reagent using a detection means for the detectable agent; and

c. comparing the level of detectable agent measured in step b) with a standard curve to determine the level of antibody bound to the capture reagent.

9. The method of claim 8 , wherein said detectable agent is a labelled secondary antibody.

10. The method of claim 1 , wherein said capture reagent is a baculovirus-expressed protein.

11. The method of claim 1 , wherein said immunogenic composition comprises a recombinant protein selected from:

a. a PCV2 ORF2 protein having at least 95% sequence identity with the sequence of SEQ ID NO:23, and

b. an avian influenza hemagglutinin of H5N1 virus comprisng an amino acid sequence having at least 95% sequence identity with the sequence of SEQ ID NO:24.

12. The method of claim 1 , wherein said immunogenic composition comprises a recombinant protein produced by a baculovirus expression system in cultured insect cells and one or more antigens from an RNA virus capable of infecting insect cells.

13. The method of claim 12 , wherein said RNA virus capable of infecting insect cells has been inactivated.

14. The method of claim 1 , wherein the mammal or a bird is a pig or a chicken.

15. The method of claim 1 , wherein the biological sample is whole blood, blood plasma, serum, urine, oral fluids, or any combination thereof.

16. The method of claim 1 , wherein said capture reagent is said RNA virus, and wherein said RNA virus is an inactivated RNA virus.

17. The method of claim 1 , wherein said antibodies are specific for an inactivated RNA virus.

18. The method of claim 1 , wherein said capture reagent is a baculovirus-expressed protein.

19. A kit for differentiating a non-vaccinated mammal or bird from a mammal or bird which has received an immunogenic composition, comprising a capture reagent immobilized to a solid support, wherein the capture reagent specifically binds antibodies specific for a rhabdovirus antigen and is selected from:

a. a recombinant polypeptide comprising a sequence having at least 95% sequence identity with any one of SEQ ID NOs: 1 to8;

b. a RNA virus which comprises a polypeptide comprising an amino acid sequence having at least 95% sequence identity with the sequence of SEQ ID NO:1 and/or SEQ ID NO:7; and

c. polypeptide fragments consisting of 5 to 100 consecutive amino acid residues of SEQ ID NO:1 or SEQ ID NO:7.

20. The kit of claim 19 , wherein said capture reagent is said RNA virus, and wherein said RNA virus is capable of infecting insect cells.

21. The kit of claim 19 , wherein the capture reagent is the RNA virus, and wherein the RNA virus is an inactivated RNA virus.