Research Articles (Biochemistry)

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Browsing Research Articles (Biochemistry) by Subject "Antibody response"

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    Conservation implications of avian malaria exposure for African penguins during rehabilitation
    (Academy of Science of South Africa, 2017-02-15) Botes, Annelise; Thiart, Hanlie; Parsons, Nola J.; Bellstedt, Dirk U.
    ENGLISH ABSTRACT: The African penguin (Spheniscus demersus) is the only penguin species that breeds on the African continent and it is currently classified as endangered. Its conservation is assisted by the Southern African Foundation for the Conservation of Coastal Birds (SANCCOB) which is a seabird rehabilitation facility based at the Rietvlei Wetland Reserve in Tableview, Cape Town. Despite the success of SANCCOB in rehabilitating diseased, injured or oiled penguins, significant mortalities have occurred at the facility as a result of avian malaria. Avian malaria can be contracted during rehabilitation during which penguins are inadvertently exposed to additional threats. An enzyme-linked immunosorbent assay (ELISA) was used to assess the anti-Plasmodium antibody levels of penguins to avian malaria on entry into the SANCCOB facility from 2001 to 2004 and during their rehabilitation process. Using blood smear data, avian malaria prevalence and malaria-related deaths were also monitored from 2002 to 2013. Significant increases in anti-Plasmodium antibody levels after admission were found during summer months. New infection and not parasite recrudescence was concluded to be the cause of this increase. This source was confirmed by a dramatic drop in penguin mortalities upon exclusion of mosquito vectors in 2008. Mortalities did not depend on the birds’ abilities to produce an anti-Plasmodium antibody response and oiling had no influence on immunity or prevalence of avian malaria infections. This study highlights the importance of mosquito vector control to control pathogen exposure in wild bird rehabilitation centres. Significance: • Efforts to assist with the conservation of endangered species can unintentionally add to the conservation burden. • Rehabilitation influences exposure of African penguins to avian malaria. • Avian malaria prevalence and mortality are not influenced by oiling or anti-Plasmodium antibody responses. • Vector control can limit avian malaria exposure in wild bird rehabilitation centres.
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    DNA vaccines against mycoplasma elicit humoral immune responses in ostriches
    (Frontiers Media, 2019-05-14) Wium, Martha; Jonker, Hester Isabella; Olivier, Adriaan Jacobus; Bellstedt, Dirk Uwe; Botes, Annelise; Leite, Luciana
    In ostriches, the population densities resulting from intensive rearing increases susceptibility to pathogens such as mycoplasmas. In addition to good management practices, vaccination offers an attractive alternative for controlling mycoplasma infections in food animals, instead of using antibiotics, which often leave unacceptable residues. The use of live attenuated vaccines, however, carry the concern of reversion to virulence or genetic recombination with field strains. Currently there are no commercially available vaccines against ostrich-infecting mycoplasmas and this study therefore set out to develop and evaluate the use of a DNA vaccine against mycoplasma infections in ostriches using an OppA protein as antigen. To this end, the oppA gene of “Mycoplasma nasistruthionis sp. nov.” str. Ms03 was cloned into two DNA vaccine expression vectors after codon correction by site-directed mutagenesis. Three-months-old ostriches were then vaccinated intramuscularly at different doses followed by a booster vaccination after 6 weeks. The ability of the DNA vaccines to elicit an anti-OppA antibody response was evaluated by ELISA using the recombinant OppA protein of Ms03 as coating antigen. A statistically significant anti-OppA antibody response could be detected after administration of a booster vaccination indicating that the OppA protein was successfully immunogenic. The responses were also both dose and vector dependent. In conclusion, the DNA vaccines were able to elicit an immune response in ostriches and can therefore be viewed as an option for the development of vaccines against mycoplasma infections.