The use of an indirect ELISA with protein G-peroxidase conjugate and a blocking ELISA to demonstrate recent bluetongue infection in sheep.
The humoral immune response of sheep infected with bluetongue virus serotypes 3, 9 and 16 was monitored by plaque inhibition (PI), blocking ELISA (BELISA) and indirect ELISA over a period of 63 days post-infection. Results indicated that testing of a single plasma or serum sample by both a BELISA and an indirect ELISA using a recombinant streptococcal protein G (PrG) peroxidase conjugate enabled an assessment of the proximity of a recent infection based on the failure of PrG to bind ovine IgM class antibodies. When BELISA and indirect ELISA results were expressed as a ratio, values indicative of recent infection (> or = 5) were observed for an average duration of 16.5 days (range 8 to 23 days) following the initial detection of antibody by BELISA. This approach has potential to improve diagnosis of a wide range of virus infections by providing an indicator for the relationship of serological status with a recent infection. However, where reinfection may occur, as with bluetongue virus, alternative methods may be required for definitive diagnosis.
CSIRO Australian Animal Health Laboratory, Institute of Animal Production and Processing, Geelong.
R A
RA
Lunt
S D
SD
Blacksell
K M
KM
Newberry
D000818:Animals; D000914:Antibodies, Viral / Q000096:biosynthesis / Q000097:blood*; D001819:Bluetongue / Q000097:blood / Q000175:diagnosis* / Q000276:immunology; D001820:Bluetongue virus / Q000145:classification / Q000276:immunology*; D003289:Convalescence; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D008297:Male; D012703:Serotyping; D012756:Sheep / Q000276:immunology; D013997:Time Factors
D000914:Antibodies, Viral