Relationship between lesion area and serum Hp during a 6 week infestation of sheep with Psoroptes ovis. Panel a: Serum from a sheep infested with P. ovis in trial TCT where the lesion resolved naturally after 4 weeks (Sheep 1); Panel b: Serum from an infested sheep in the same trial where the lesion had continued to expand during the 6 week time course (Sheep 5). Immunoblots were probed with a rabbit polyclonal anti-human Hp antibody (Abcam) and the secondary antibody conjugate used was a swine anti-rabbit IgG HRP (Dako). The image was visualised by ECL Plus and ImageQuant. Band volumes (at 45 kDa) were quantified by ImageQuant TL software.