Clinical evaluation and antibody responses in sheep after primary and secondary experimental challenges with the mange mite Sarcoptes scabiei var. ovis

Abstract

In this work the clinical evolution and the specific serum IgG and IgE antibody responses in sheep after primary (n=10) and secondary (n=4) experimental challenges with the mange mite Sarcoptes scabiei var. ovis were studied. The primary infection was characterized by the development of mange lesions in all sheep, a detection of live S. scabiei mites in 70% skin scrapings taken in week 10 post-challenge (PC), strongly raised and sustained specific IgG levels and a more moderate but continuous rise in specific IgE levels. Seroconversion was detected for IgG and IgE by ELISA in 90% and 60% of the sheep in week 8 PC, respectively. By Western-blotting (WB), ten IgG-reactive bands (36-120 kDa) and four IgE-reactive bands (90-180 kDa) were observed in week 8 PC. Following the secondary challenge the ewes developed a smaller area of mange lesion than that seen following primary challenge and live S. scabiei mites were not detected in skin scrapings collected in week 8 PC, suggesting that sheep had developed immunity to re-infection. Compared to primary infection, the specific IgG secondary antibody levels were transient, but in contrast there was an anamnestic IgE response, resulting in an elicitation of specific serum IgE levels in week 2 PC significantly higher than those demonstrated after primary infection. WB analysis revealed one additional IgG-reactive band (180 kDa) and no additional IgE-reactive bands. Determining the immunodiagnostic or vaccination value of the IgG-reactive antigens and IgE-reactive allergens detected requires further studies.

Antibody Responses to Sarcoptes scabiei Apolipoprotein in a Porcine Model: Relevance to Immunodiagnosis of Recent Infection

“…A lack of IgE binding during primary infestation was observed in a significant proportion of S. scabiei infected dogs [27] and sheep [56], whereas in another study goats mounted a strong IgE responses to both primary and repeated mite challenge [46]. IgE responses also increased significantly in sheep during secondary infestation [56].From this it appears that differences may exist between the immune responses of humans and other animals to scabies, and between primary and secondary infestations. Thus, future ELISA design should consider the possibility of using different secondary antibodies for diagnosis in medical and veterinary settings.…”

A Proteomic Analysis ofSarcoptes scabiei(Acari: Sarcoptidae)

“…A variety of immunoblotting studies have reported the molecular weights of various antigens recognized by the antibodies in the serum from scabies-infested hosts Arlian et al 1996aArlian et al , 2004aMorgan et al 1997;Arlian and Morgan 2000;Schumann et al 2001;Tarigan and Huntley 2005;Yadav et al 2006;Zalunardo et al 2006;Casais et al 2007;Rambozzi et al 2007;Rodriguez-Cadenas et al 2010;Hejduk et al 2011;Jakubek et al 2012). Yet little data identifying the proteins involved have been reported.…”

Crusted scabies is associated with increased IL‐17 secretion by skin T cells

“…Extremely high levels of IgE antibody have been reported in patients with crusted scabies, indicative of a Th2-biased immune response (5,6,15,32). However, studies in goat and sheep models suggested that high IgE levels may indicate protective immune responses (33,34), and thus high levels of IgE may therefore not be directly related to a dysregulated immune response leading to the development of crusted scabies. PBMCs isolated from patients with crusted scabies secreted higher levels of IL-4, IL-5 and IL-13 and lower levels of IFNc compared with those of ordinary scabies patients (15).…”