Characterization and evaluation of a Sarcoptes scabiei allergen as a candidate vaccine

Abstract

BackgroundSarcoptic mange caused by the mite Sarcoptes scabiei is a worldwide disease affecting both humans and animals. Here we report the molecular characterization and evaluation of a recombinant S. scabiei tropomyosin (SsTm) protein in a vaccination trial in rabbits.MethodsThe full-length cDNA was cloned in a bacterial pET vector, and the recombinant protein was expressed in BL21 (DE3) cells and purified. Using specific rabbit antiserum, tropomyosin was localized immunohistochemically in mite tissue sections. Vaccination trials with the recombiant SsTm was carried out in New Zealand rabbits.ResultsThe full-length open reading frame (ORF) of the 852 bp cloned gene from S. scabiei encodes a 32.9 kDa protein. The amino acid sequence showed 98.94%, 97.89% and 98.59% homology to Dermatophagoides farina and Dermatophagoides pteronyssinus group 10 allergens and Psoroptes ovis tropomyosin, respectively. Tropomyosin was localized immunohistochemically in mite tissue sections mainly in the mouthparts, legs and integument of the epidermis. The predicted cross-reactivity of SsTm indicated that it is an allergenic protein. While vaccination with the recombiant SsTm resulted in high levels of specific IgG (P < 0.01), a low IgE antibody response and no significant protection against S. scabiei challenge were observed. After challenge, specific IgG levels remained significantly higher than the control (P < 0.01), while changes of total IgE levels were not significant (P > 0.05). However, the lesion areas in the vaccination group decreased at the end of the experiment compared with controls.ConclusionsAlthough vaccination with recombinant SsTm did not efficiently control sarcoptic mange in rabbits, the immunogenic properties of tropomyosin suggest it may be developed as a vaccine with alternative adjuvants or delivery methods.

Tackling scabies: novel agents for a neglected disease

“…Recombinant Sarcoptic scabiei tropomyosin (SsTm) is an immunogenic protein that has been evaluated in sarcoptic mange of rabbits. It failed to show efficacy and probably requires alternative adjuvants or delivery methods to be developed into an effective vaccine . A Sarcoptes scabiei var cuniculi DNA vaccine, which encodes paramyosin, was immunogenic and elicited both humoral and cellular immunity in mice .…”

Molecular Identification of Sarcoptes Scabiei Var. Cuniculi From Surabaya and Malang Regions of East Java

“…Therefore, several studies have been aimed at developing molecular subunit vaccines using recombinant DNA cloned from S. scabiei. [16][17][18][19] 8000 12 Next, PCR to amplify a 289 bp region of the COX1 gene was performed using the forward primer 5'-TCTTAGGGGCTGGATTTAGTATG-3' and the reverse primer 5'-AGTTCCTCTACCAGTTCCAC-3'. PCR was performed in an automatic thermocycler (Biorad) with an initial denaturation step at 95 °C for 5 min, and 35 cycles of 94 °C for 1 min, 55 °C for 1 min, and 72 °C for 1 min, followed by a final extension step at 72 °C for 5 min.…”

Vaccination with recombinant actin from scab mites and evaluation of its protective efficacy against Psoroptes cuniculi infection

“…Second, we have not seen any published references indicated that QuilA adjuvant might depress IgE levels. At last, a colleague in our laboratory had finished her study with exact the same doze of the same adjuvant (QuilA), and the results of her study did not show IgE depression in S. Scabiei ‐infected rabbits . Therefore, we concluded that it was not the QuilA adjuvant that depressed IgE levels, but something else which worth more further study in the future.…”