An Antibody Persistent and Protective Two rSsCLP-Based Subunit Cocktail Vaccine against Sarcoptes scabiei in a Rabbit Model

Vaccination with a cocktail vaccine elicits significant protection against Sarcoptes scabiei in rabbits, whereas the multi-epitope vaccine offers limited protection

Sarcoptes scabiei cause scabies in humans or sarcoptic mange in animals. Currently, information regarding vaccines against S. scabiei is limited and no commercial vaccine is available. In present study, we expressed and mixed recombinant S. scabiei serpin (rSs-serpin), recombinant S. scabiei chitinase-like protein-5 [rSs-CLP5] and -12 [rSs-CLP12] as a cocktail vaccine (three proteins mixed), and also a multi-epitope protein derived from these three S. scabiei genes was expressed as a vaccine candidate to evaluate the effects of two vaccine strategies. Four test groups (n = 12 per group) and a control group (n = 12 per group) were involved in this vaccination trial. The results showed that 91.67% (11/12) and 83.33% (10/12) of rabbits exhibited no detectable skin lesions from S. scabiei infestation in cocktail vaccine groups, whereas two multi-epitope groups produced only a few rabbits (5/12, 6/12) having no detectable skin lesions. Four test groups displayed significant increases in specific IgG antibodies (Abs) and total IgE Abs after immunized with recombinant proteins. Taken together, our data demonstrated a mixture of rSs-serpin, rSs-CLP5 and rSs-CLP12 was a promising vaccine candidate that induced robust immune protection and could significantly decrease mite populations to reduce the direct transmission between rabbits. However, vaccination with the multi-epitope protein showed limited protection in rabbits.

Evaluation of the immune protective effects of rEmMIC2 and rEmMIC3 from Eimeria magna in rabbits

Eimeria magna is a common pathogen in rabbits, which results in lethargy, weight loss, diarrhea, and even death in severe cases after infection. The current method for preventing rabbit coccidiosis is to add anticoccidial drugs to the diet. However, there are many concerns about drug resistance and drug residues. In our study, the rEmMIC2 and rEmMIC3 proteins were cloned and expressed to evaluate potential as recombinant subunit vaccine candidate antigens. The protective effects of rEmMIC2 and rEmMIC3 were evaluated by the relative weight gain ratio, oocyst decrease rate, anticoccidial index, feed conversion ratio, pathological alterations, clinical symptoms, specific IgG antibody, and cytokine levels in rabbits. The molecular weights of rEmMIC2 and rEmMIC3 were 18.69 kDa and 17.47 kDa, respectively. After the coccidia challenge, the control groups showed anorexia and soft poop, whereas the experimental group showed few anorexia symptoms. Significantly different from the control group, the relative weight gain ratios of the immunized rEmMIC2 and rEmMIC3 groups were 78.37% and 75.29%, respectively, and the oocyst reduction was 77.95% and 76.09%, respectively, and the anticoccidial index was 171.12 and 169.29, respectively. IgG antibody, IFN-γ, IL-4, IL-10, and IL-17 levels were significantly increased in the experimental group. The results showed that rEmMIC2 and rEmMIC3 have potential as vaccine candidate antigens.

Immunomodulatory effects of two recombinant arginine kinases in Sarcoptes Scabiei on host peripheral blood mononuclear cells

Background

As an important zoonotic parasitic disease with global distribution, scabies causes serious public health and economic problems. Arginine kinase (AK) is involved in cell signal transduction, inflammation, and apoptosis. Two AKs were identified in Sarcoptes scabiei, but their functions in the host immune response remain unclear.

Methods

rSsAK-1 and rSsAK-2 were expressed, purified, and immunolocalized. The effects of rSsAK-1 and rSsAK-2 on rabbit PBMC proliferation, apoptosis, and migration; Bcl-2, Bcl-xl, Fas, Bax, and NF-κB transcription levels; and IL-2, IFN-γ, IL-4, IL-10, TGF-β1, and IL-17 secretion were detected.

Results

rSsAK-1 and rSsAK-2 were cloned and expressed successfully. Both enzymes were ~57 kDa and contained 17-kDa tagged proteins, and had good catalytic activity and immunoreactivity. The proteins were located in the S. scabiei exoskeleton, chewing mouthparts, legs, stomach, and intestine. SsAK-1 and SsAK-2 were secreted in the pool and epidermis of the skin lesions, which may be involved in S. scabiei–host interaction. rSsAK-1 and rSsAK-2 significantly promoted cell proliferation, induced cell migration, inhibited apoptosis, and increased Bcl-2, Bcl-xl and NF-κB (p65) transcription levels concentration-dependently, and inhibited IL-2, IFN-γ, and IL-10 secretion and promoted IL-4 and IL-17 secretion.

Conclusion

rSsAK-1 and rSsAK-2 might increase Bcl-2 and Bcl-xl expression by activating the NF-κB signaling pathway to promote cell proliferation and inhibit apoptosis, which induced PBMC survival. By inducing PBMC migration to the infection site, rSsAK-1 and rSsAK-2 shifted the Th1/Th2 balance toward Th2 and changed the Th17/Treg balance, which indicated their immune role in S. scabiei allergic inflammation.

Mange in Rabbits: An Ectoparasitic Disease with a Zoonotic Potential

Mange in rabbits is a very important parasitic disease causing high losses. The disease is caused mainly by Sarcoptes scabiei, Psoroptes cuniculi, Cheyletiella parasitovorax, and Notoedres cati. Body mange and ear mange are the most common forms of this disease in rabbits. Animals can get mite infestation through direct contact with infected animals or contaminated fomites. This infestation is characterized by zoonotic nature and public health burden. The skin affection is characterized by pruritus, alopecia, severe cachexia, and sometimes death. Infestation is diagnosed mainly by skin scraping and microscopic examination. Control measures mainly depend on the use of different types of systemic and topical acaricides and the use of natural products and supportive elements. Vaccine is not commercially available and is still under investigation. Accordingly, this review article was designed to shed the light on the mange disease in rabbits in terms of mite's infestation and susceptibility, clinical manifestations, zoonosis, diagnosis, and control strategies.

Sarcoptes Infestation. What Is Already Known, and What Is New about Scabies at the Beginning of the Third Decade of the 21st Century?

Currently, there are three known subtypes of scabies: ordinary, crusted, and bullous. The worldwide prevalence of scabies remains high in the 21st century. To decrease the social, economic, and psychological impact on the enormous population infected, a lot of important work has been completed over the last 20 years concerning the management of scabies. For example, a standardization of guidelines for the treatment of scabies has been completed and programs have been designed for the prevention and treatment in endemic populations, called mass drug administrations. Unfortunately, these only apply to the ordinary form of scabies. Moreover, resistance to the drugs currently used in treatment is growing, which imposes the need to search for new treatments. For this purpose, new acaricides are being developed to enhance the therapeutic options for the patients' benefit and effectively treat this disease. There is also the necessity for prevention before the development of scabies. An effective vaccine has the potential to protect people before this disease, especially in endemic areas. Unfortunately, there are no such vaccines against Sarcoptes yet.