Immunological and epidemiological investigations in South African ostriches and penguins

Botes, Annelise (2004-04)

Dissertation (PhD)--University of Stellenbosch, 2004

Thesis

ENGLISH ABSTRACT: Newcastle disease (NO) and mycoplasma infections in ostriches have considerable economic implications for the South African ostrich industry in that NO is a limiting factor in the export of ostrich products to the European Union and mycoplasma infections cause stock losses, reduced production, reduced hatchability and downgrading of carcasses. In the first section of this dissertation, the role of passively acquired and mucosal immunity in protection of ostrich chicks against Newcastle disease virus (NOV) was investigated. Ostrich hen serum IgG and yolk IgY were isolated and characterized, and the transfer of maternal anti-NOV antibodies to the egg yolk was determined using an enzyme-linked immunosorbent assay (ELISA). Results indicated that anti-NOV antibodies were successfully transferred from the ostrich hen to the egg yolk. In addition, ostrich IgA was isolated, characterized and rabbit anti-ostrich IgA antibodies produced and used for measuring mucosal anti- NOV IgA antibodies produced in response to mucosal vaccination. Results indicated that the live La Sota vaccine stimulates IgA production and thus mucosal immunity in ostrich chicks. In the second section of this dissertation, ostrich mycoplasmas were isolated and identified using 16S rRNA gene sequencing. These sequences indicated that ostriches carry three unique mycoplasmas, which are phylogenetically quite divergent. The 16S rRNA gene sequences of the ostrich mycoplasmas were subsequently used for the development of specific primers for the detection and diagnosis of mycoplasma infections in ostriches by PCR. The last section of this dissertation focuses on avian malaria in African penguins and the management of this disease during rehabilitation. The Foundation for the Conservation of Coastal Birds (SANCCOB) is a seabird rescue and rehabilitation centre, which is largely dedicated to the rehabilitation of diseased, injured and oiled penguins. Significant mortalities due to avian malaria occur at this facility. The aim of this study was the development of an ELISA for the purpose of assessing the natural levels of anti-Plasmodium antibodies in African penguins on entry into the SANCCOB facility and during rehabilitation. Results indicated significant increases in anti- Plasmodium antibody levels after entry, which was not influenced by oiling. Infection with malaria and not parasite recrudescence was viewed to be the cause of this increase, indicating a possible role of the SANCCOB facility in exposing penguins to avian malaria.

AFRIKAANSE OPSOMMING: Newcastlesiekte (NS) en mikoplasmainfeksies in voltruise het geweldige ekonomiese implikasies vir die Suid-Afrikaanse volstruisbedryf. Die rede hiervoor is dat NS 'n beperkende faktor in die uitvoer van volstruisprodukte na die Europese Unie is, en mikoplasmainfeksies tot kudde verliese, verlaagde produksie en uitbroei asook lae gradering van karkasse lei. In die eerste gedeelte van hierdie proefskrif is die rol van passiewe- en mukosale-immuniteit in die beskerming van volstruiskuikens teen NS virus (NSV) ondersoek. Volstruishenserum IgG en eier IgY is geïsoleer en gekarakteriseer en die oordrag van maternale anti-NSV antiliggame na die eier ondersoek met behulp van 'n 'enzyme-linked immunosorbent assay' (ELISA). Resultate het getoon dat anti-NSV antiliggame suksesvol van die hen na die eier oorgedra is. Volstruis IgA is ook geïsoleer, gekarateriseer en konyn anti-volstruis IgA antiliggame geproduseer wat gebruik is vir die bepaling van mukosale anti-NSV IgA antiliggame in reaksie op mukosale immunisering. Resultate het getoon dat lewendige La Sota entstof IgA produksie stimuleer en dus tot mukosale-immuniteit in volstruiskuikens lei. In die tweede gedeelte van hierdie proefskrif is volstruismikoplasmas geïsoleer en geïdentifiseer met behulp van 16S rRNA geenopeenvolgingsbepalings. Hierdie volgordes het getoon dat drie unieke mikoplasmas in volstruise voorkom wat filogeneties verskillend blyk te wees. Die 16S rRNA geenopeenvolgings van die volstruismikoplasmas is gebruik vir die ontwikkeling van spesifieke inleiers vir die PKR identifisering en diagnose van mikoplasmainfeksies in volstruise. Die laaste gedeelte van hierdie proefskrif fokus op voëlmalaria in die Afrika pikkewyn en die bestuur van hierdie siekte gedurende rehabilitasie. Die 'South African Foundation for the Conservation of Coastal Birds' (SANCCOB) is 'n seevoëlreddingsen rehabilitasie-sentrum vir siek, beseerde en ge-oliede pikkewyne. Hierdie sentrum het egter aansienlike vrektes as gevolg van voëlmalaria. In hierdie studie is 'n ELISA ontwikkel vir die bepaling van natuurlike anti-Plasmodium antiliggaamvlakke van pikkewyne by aankoms en tydens rehabilitasie by SANCCOB. Resultate het 'n toename in anti-Plasmodium antiliggaamvlakke getoon na toelating wat nie beïnvloed is deur olie nie. Hierdie toename kan toegeskryf word aan nuwe malariainfeksies en nie 'n heruitbraak van bestaande infeksies nie wat daarop dui dat pikkewyne aan voëlmalaria blootgestel word by die SANCCOB-sentrum.

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