Immunological and epidemiological investigations in South African ostriches and penguins

[摘要] ENGLISH ABSTRACT:Newcastle disease (NO) and mycoplasma infections in ostriches have considerableeconomic implications for the South African ostrich industry in that NO is a limitingfactor in the export of ostrich products to the European Union and mycoplasmainfections cause stock losses, reduced production, reduced hatchability anddowngrading of carcasses. In the first section of this dissertation, the role of passivelyacquired and mucosal immunity in protection of ostrich chicks against Newcastledisease virus (NOV) was investigated. Ostrich hen serum IgG and yolk IgY wereisolated and characterized, and the transfer of maternal anti-NOV antibodies to theegg yolk was determined using an enzyme-linked immunosorbent assay (ELISA).Results indicated that anti-NOV antibodies were successfully transferred from theostrich hen to the egg yolk. In addition, ostrich IgA was isolated, characterized andrabbit anti-ostrich IgA antibodies produced and used for measuring mucosal anti-NOV IgA antibodies produced in response to mucosal vaccination. Results indicatedthat the live La Sota vaccine stimulates IgA production and thus mucosal immunity inostrich chicks. In the second section of this dissertation, ostrich mycoplasmas wereisolated and identified using 16S rRNA gene sequencing. These sequences indicatedthat ostriches carry three unique mycoplasmas, which are phylogenetically quitedivergent. The 16S rRNA gene sequences of the ostrich mycoplasmas weresubsequently used for the development of specific primers for the detection anddiagnosis of mycoplasma infections in ostriches by PCR.The last section of this dissertation focuses on avian malaria in African penguins andthe management of this disease during rehabilitation. The Foundation for theConservation of Coastal Birds (SANCCOB) is a seabird rescue and rehabilitationcentre, which is largely dedicated to the rehabilitation of diseased, injured and oiledpenguins. Significant mortalities due to avian malaria occur at this facility. The aim ofthis study was the development of an ELISA for the purpose of assessing the naturallevels of anti-Plasmodium antibodies in African penguins on entry into the SANCCOBfacility and during rehabilitation. Results indicated significant increases in anti-Plasmodium antibody levels after entry, which was not influenced by oiling. Infectionwith malaria and not parasite recrudescence was viewed to be the cause of thisincrease, indicating a possible role of the SANCCOB facility in exposing penguins toavian malaria.

[发布机构] Stellenbosch University