Figure 5.
Infection by BoHV-4 strains expressing membrane anchored forms of IRAC elicits antibody response against IRAC. (a) Titres of anti-BoHV-4, anti-IRAC I and anti-IRAC II antibodies in sera from the two individual rabbits per group infected with the V. test strain of BoHV-4 or with the recombinant BoHV-4 V. test IRAC I, -IRAC II, -IRAC I HA or -IRAC II HA excised strains. Titres were evaluated for anti-BoHV-4, anti-IRAC I or anti-IRAC II antibodies by indirect immunofluorescent staining of CRFK cells transfected with plasmids expressing soluble WT IRAC. Serum titres are expressed as the reciprocal of the highest dilution of the serum that gave a positive signal on immunofluorescence (equivalent data were obtained in another experiment). (b) The ability of IRAC I and IRAC II to inhibit the complement alternative pathway of rabbit was tested using the AH50 assay as described in the methods. The data are expressed as the percentage of lysis observed when mock-infected concentrated cell supernatant was added to the test. (c) Effect of IRAC immunization on tick feeding. Female ticks were fed on vaccinated rabbits one month after the second immunization. Infested rabbits were checked daily. Anchored and detached ticks were counted. The number of anchored ticks (expressed as a percentage of the whole population) was plotted.