Research Article: Characterization of Tunga penetrans Antigens in Selected Epidemic Areas in Murang’a County in Kenya

Date Published: March 20, 2015

Publisher: Public Library of Science

Author(s): Jamleck N. Mwangi, Hastings S. Ozwara, Joshua M. Motiso, Michael M. Gicheru, Joseph M. Vinetz.

Abstract: Tunga penetrans are fleas that cause tungiasis, a condition characterized by high transmission rate due to poor housing conditions, social neglect and inadequate health care in economically disadvantaged communities in developing countries. This study therefore aimed at characterizing jiggers antigens to identify immunodominant ones to help understand immunological behavior of the parasite that would otherwise be important in future control of the parasite. Samples were gravid fleas and blood samples from infested individuals in Kahuro and Murang’a East district in Murang’a County. Freeze and thaw was used to extract soluble proteins from the fleas. Ouchterlony Double immunodiffusion was used to assess antigen-antibody reactions between extracted soluble protein and the serum from immunized rats, Rattus norvegicus prior to analysis of human sera. These results were comparable to results of immunoelectrphoresis. Jigger protein isolates were analyzed in Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis technique (SDS—PAGE), against Pharmacia standard protein markers. Further analysis of jigger antigens against pooled human sera from infested victims in Western blot revealed three immunodominant antigens. Using simple regression analysis molecular weights of the three immunodominant antigens were estimated as 51.795, 23.395 and 15.38 kDa respectively. These results are important since they would help understand immunological behavior of the parasites. This would help to create basis for designing and improving approaches against jiggers such as development of immune prophylaxis to complement social science approaches that is mainly concerned with maintenance of high standards of hygiene.

Partial Text: Tungiasis is normally considered as just an entomological nuisance [1]. This make it fail to catch the attention of researchers and health care professionals. Moreover, high incidence rate is normally linked to poverty and lack of proper self hygiene. In Brazil doctors and other health officials neglects this ectoparasite; they hardly diagnose the disease when a patient visits a health centre due to other ailments [2]. The pathology and body immune responses associated with this ectoparasite are not well understood that could be basis for a lasting solution [3]. Therefore, failure to understand the biological behaviors of these parasites and characteristic of their antigens has contributed to unspecific and ineffective intervention strategies. Communities have all along depended on traditional methods that are not just ineffective [4] but can also lead to spread of HIV through sharing contaminated sharp objects.

Rats are appropriate animal model in tungiasis studies [22], [23]. In the current study immunized rats were found to react to T. penetrans antigens whereby one precipitate band was formed in both immunodiffusion and immunoelectrophoresis assays. This was an important pre-analysis of jigger antibodies prior to analysis of human sera since human immune system could similarly react to the same antigens. This was key as highlighted in Box 1. It was observed that, though one can induce immune responses in animals like rats, the response was limited the same type of protein molecules since only one precipitate band was formed. In addition people too do not react to a variety of jiggers antigens since only three major antigens were observed. This could be attributed to the fact that jiggers being ectoparasites are not largely exposed to systemic circulation.



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