Inaug.-diss.-Bern. / Lebenslauf.

No description available.

The factors governing the reaction between chloroform and hemoglobin by which the hemoglobin of the blood may be precipitated were studied, and a process, based upon this reaction, for the separation of a clear sterile serum from old defibrinated blood antitoxin was devised. It is shown that the yield of clear serum separated by this process approximates 70% of the original volume and that the product of the process is free from bacterial contamination. While it is shown by analysis that the globulin content of the serum suffers a slight loss, when the serum is treated by this process, potency tests indicate that the loss in antibodies that occurs during clarification may be disregarded. / Master of Science

Call number: LD2668 .T4 1958 W47

Classical Swine Fever (CSF) is a highly contagious viral disease of swine that causes major losses to pig production. CSF virus is a member of the genus Pestivirus of the family Flaviviridae and is closely related antigenically to other Pestiviruses, Bovine Viral Diarrhoea (BVD) virus and Border Disease (BD) virus. In the Lao People’s Democratic Republic (Laos), CSF has been recognised as a disease that causes significant loss to the smallholder pig sector. However, there exists in Laos a deficiency in fully understanding the epidemiology and impact of CSF, together with limitations in being able to reliably detect CSF outbreaks in a timely manner. (For complete abstract open document)

English: Common warthogs (Phacochoerus africanus) and bushpigs (Potamochoerus larvatus), were experimentally infected with classical swine fever virus (CSFv) following the diagnosis of classical swine fever (CSF) subtype 2.1 in 2005 in domestic pigs in South Africa. At that time, no data regarding their susceptibility or the potential lesions in these wild suids were available. Seven sub-adult warthogs and six bushpigs were captured, taken to the high containment facilities of the Transboundary Animal Diseases Programme of the Agriculture Research Council (ARC) - Onderstepoort Veterinary Research Institute, and infected intranasally with the South African isolate. In each experiment, two in-contact control animals of the same species verified intraspecies transmission, while two domestic pigs were used to demonstrate virus virulence and viability. Surviving animals were euthanized 44 days post infection. Formalin-fixed tissue samples collected from all experimental animals were evaluated for histological lesions. The warthogs, which remained clinically normal throughout the study, developed histological lesions that were inconsistently present and sometimes subtle. Three warthogs, including one in-contact control, developed distinct perivascular lymphoplasmacytic cuffing in their brains. Subtle lesions included scant lymphoplasmacytic infiltration of various organs, occasionally accompanied by perivascular cuffing. In contrast, the bushpigs developed overt clinical signs similar to CSF in domestic pigs. Four animals out of six, including two in-contact controls, died or were euthanized during the trial. On post mortem examination, intestinal necrosis and ulceration, purulent rhinitis and pneumonia were present. Acutely affected animals developed lymphoid necrosis and depletion whilst surviving individuals showed perivascular lymphoplasmacytic cuffing in multiple organs. Immunohistochemical demonstration of CSFv antigen using a commercially available mouse monoclonal antibody, WH303, revealed intense, widespread labelling in most tissues of all the warthogs and bushpigs as well as the four domestic pigs used as controls during the trial. A wide range of cell types and tissues reacted with the antibody. These included: mononuclear cells (monocyte-macrophages, lymphocytes and plasma cells), follicular reticular cells, epithelial cells, vascular endothelial cells, mesothelial cells, smooth muscle cells and fibroblasts. Tissues that were labelled included tonsil, lymph nodes, spleen, third eyelid, adrenal gland, urinary bladder, skin, liver, kidney, lung, certain cells within central nervous tissue like the choroid plexus, various parts of the gastro-intestinal tract as well as glandular tissue like the pancreas and salivary gland. The tonsils were the most consistently labelled tissue, while no labelling was noted in myocytes of skeletal or cardiac muscle. From the present work, it was concluded that these wild Suidae are susceptible to CSFv and intra-species transmission under experimental conditions can occur. / Afrikaans: Wilde Afrika varke, nl. vlakvarke (Phacocoerus africanus) en bosvarke (Potamochoerus larvatus) was eksperimenteel infekteer met europese varkpes virus nadat die siekte in kommersiële mak varke diagnoseer is in 2005 (dit was tipeer as subtipe 2.1). Geen inligiting oor die vatbaarheid of potensiële letsels weens europese varkpes infeksie in hierdie wilde varke was beskikbaar nie. Sewe wilde onvolwasse vlakvarke en ses bosvarke is gevang, na die isolasie eenheid van die Onderstepoort Veterinêre Instituut se oor-grens siekte afdeling geneem en intranasal geïnfekteer met die Suid-Afrikaanse isolaat van 2005. Twee in-kontak kontrole diere van dieselfde spesie is gebruik in elke eksperiment om intra-spesie oordraging vas te stel en twee mak varke om virus lewensvatbaarheid en virulensie te demonstreer. Oorlewende diere is uitgesit na 44 dae. Formalien gefikseerde weefsel monsters is versamel van hulle, sowel as van diere wat uitgesit is tydens die eksperiment. Die vlakvarke was klinies normal regdeur die eksperiment, maar het wel histologiese letsels ontwikkel wat subtiel was en ook nie altyd teenwoordig in alle gevalle nie. Drie vlakvarke, waarvan een ‘n in-kontak dier was, het prominente limfo-plasmasitiese perivaskulêre flensing in hul breine ontwikkel. Subtiele letsels het klein hoeveelhede limfoplasmasitiese infiltrasies in verskeie organe en somtyds perivaskulêre flensing ingesluit. In teenstelling, het die bosvarke uitgesproke kliniese tekens soortgelyk aan Europese varkpes in mak varke, ontwikkel. Vier uit die ses diere, insluitend twee in-kontak diere is dood of uitgesit tydens die eksperiment. Met nadoodse ondersoek is daar intestinale nekrose en ulserasie, purulente rinitis en pneumonie gevind. Diere wat dood is, het limfoïede nekrose en limfoïede uitputting getoon, terwyl die oorlewende bosvarke perivaskulêre flensing met limfo-plasma selle in verskeie organe ontwikkel het. Immunohistochemiese demonstrasie van Europese varkpes virus antigen deur gebruik van ‘n kommersieël beskikbare muis monoklonale teenligaam, WH303, het duidelike wydverspreide kleuring in meeste weefsel van die die vlakvarke, bosvarke en mak varke getoon. ‘n Wye reeks van weefsel en sel tipes het met die teenliggam reageer naamlik: mononukliêre selle (monosietmakrofage en limfo-plasma selle), follikulêre retikulêre selle, epiteel, vaskulêre endoteel, mesoteel, gladde spier selle en fibroblaste. Weefsel wat gemerk is met die teenliggaam het ingesluit: mangels, limfknope, milt, derde ooglid, adrenaal klier, urienblaas, vel, lewer, nier, long, sekere selle in die sentrale senuwee stelsel, soos die koroïed pleksus, verskeie dele van die gastro-intestinale stelsel sowel as klier weefsel soos die pankreas en speekselklier. Die mangels was die mees konsekwent gemerkte weefsel, terwyl geen kleuring gevind is in miosiete van skelet of hartspier nie. Uit hierdie werk kon daar afgelei word dat vlakvarke en bosvarke vatbaar is vir Europese varkpes en dat intra-spesie oordraging plaasvind onder eksperimentele omstandighede. / Dissertation (MMedVet)--University of Pretoria, 2011. / Paraclinical Sciences / Unrestricted

Rabbit Passage of the Virus The hog cholera virus was carried through six alternate passages from pig to rabbit and then top five serial passages in rabbits. The virus could not be demonstrated in rabbit-spleen suspension prepared for the sixth serial passage in rabbits. The lack of pathogenic or antigenic properties for the pig made it impossible to detect the virus, assuming that it was present in the rabbit-spleen suspension, at the sixth serial passage. The virus did not become pathogenic for the rabbit during the alternate and serial passages, although it survived for at least 72 hours in the rabbit. No evidence or attenuation of the virus for the pig was obtained in either the alternate or serial passages. Ultraviolet Irradiation or the Virus The hog cholera virus in the form of a pig-spleen suspension was irradiated by the Westinghouse lamps CH4 and Wl793. The virus was irradiated at a distance of 15 centimeters from the lamp. The suspension was placed in an open petri dish, to a depth or l to 2 millimeters, and was constantly agitated during the irradiation. Irradiation by the CH4 lamp for 30 and 60 minutes and irradiation by the WL793 lamp for 15, 30, and 60 minutes failed to attenuate the virus for the pig. Typical hog cholera was produced in pigs injected with the irradiated virus. Nitrogen Mustard Treatment of the Virus The hog cholera virus in the form of blood virus was mixed with the nitrogen mustard, methyl-bis (β-chloroethyl)-amine, in the proportion or five milliliters of blood virus to ten milligrams of nitrogen mustard. In one lot of blood virus so treated, the virus was completely destroyed, whereas in a second lot the virus was not affected. Treatment of five milliliters of the virus, in the form of pig-spleen suspension, with ten milligrams of the nitrogen mustard completely attenuated the virus for the pig, so that, when the virus was injected into pigs, no ill effects appeared. Pigs injected with five milliliters of the mustard-treated pig-spleen virus developed a resistance to the virulent virus. The injected pigs successfully withstood the intramuscular injection or two milliliters of virulent virus, or pen exposure to cholera-infected pigs. The mustard-treated pig-spleen virus produced a satisfactory immunity in pigs injected with the treated virus 24 hours after its preparation. The mustard-treated pig-spleen virus did not spread from injected pigs to non-injected pigs kept in close contact with them. / Ph. D.

M.S.

The successful diagnosis of hog cholera in the laboratory has been hampered by the fact that small laboratory animals cannot be used satisfactorily. In this work an attempt has been made to determine whether the hog cholera virus would agglutinate red blood cells and to determine optimal conditions for the reaction. Results of comparative tests in the ability of normal and infected pig tissues to cause hemagglutination are given. The virus of hog cholera will cause agglutination of red cells, but the method is not in a practical stage at present for the routine diagnosis of hog cholera. One of the hinderances found is the variations in the agglutination of the cells from different sources, even within the same species. Serum samples failed to cause hemagglutination-inhibition in the presence of the virus. The hemagglutination or the hemagglutination-inhibition tests are not practical in their present condition, but the results show these procedures may prove to be a rapid and reliable method for the diagnosis of hog cholera after further study. This would simplify the rather difficult task of differentiating hog cholera from clinically similar diseases of swine. / M.S.

Classical Swine Fever in the Lao Peoples’ Democratic Republic: Virological, Epidemiological and Clinical studies. Classical swine fever (CSF) is a highly contagious virus infection of swine caused by classical swine fever virus (CSFV). The CSF virus is a member of the genus Pestivirus of the family Flaviviridae. Classical swine fever is believed to be endemic in Lao Peoples’ Democratic Republic (Lao PDR). Infectious diseases, including CSF, are a major constraint to pig production in developing countries such as Lao PDR. The aim of this thesis was to investigate aspects and present data regarding the nature of CSF pertinent to Lao PDR. An introduction to Lao PDR, local pig production and a review of pertinent CSF literature is presented in Chapter 1. Low levels of veterinary infrastructure have exacerbated infectious disease problems in developing countries. Chapter 2 of this thesis described the construction and refurbishment of a project laboratory in Lao PDR for the diagnosis of viral diseases, in particular CSF virus Furthermore, a diagnostic specimen submission system was adapted to the local domestic and economic conditions. Poor diagnostic facilities and lack of disease reporting systems in Lao PDR have allowed diseases to spread largely unchecked due to low levels of recognition. The process of development and assessment of appropriate diagnostic assays to the local conditions is presented and discussed in Chapter 3. ELISA and RT-PCR technologies for CSF virus detection in clinical specimens were implemented. Variations to RT-PCR methodologies were also investigated to determine the most suitable technique for the local situation. Results indicated that the RT-PCR methodology was more sensitive than ELISA for the detection of CSF virus in fresh clinical specimens. Notably, the situation was reversed when decomposed samples were tested. Methodologies for the preservation and detection of CSF virus in samples subjected to local tropical condition were also investigated. The proprietary reagent RNAlater ™ was found to be suitable for the preservation of CSF virus RNA under local conditions. Methodologies for CSF virus serology using the ELISA technique are also described. The majority of the pigs in Lao PDR are raised within village small-holder systems, with indigenous breeds being the most popular. Very little is known about the response of indigenous breed pigs to CSF virus infection. Chapter 4 described the pathogenicity of a Lao strain of CSF virus (Lao/Kham225) in both indigenous (Moo Laat) and imported pig breeds (Large white/Landrace cross-breed). Statistically significant (p = 0.05) differences in the breed-related susceptibility to CSF infection were demonstrated in clinical and haematological responses, and post-mortem pathology. The results demonstrated the course of CSF infection in the Large white/Landrace cross-breed was generally more acute than in the indigenous breed. Investigations into the epidemiology of CSF in Lao PDR are presented in Chapter 5. The distribution of CSF outbreaks during the period of mid-1997 to the end of 1999 was investigated and crude incidence results were calculated. Serological surveillance to determine the serological prevalence of CSF virus antibodies in selected regions of Lao PDR was performed during 1997 to 1999. Structured serological surveillance was performed in Vientiane Municipality, Bhorikhamxai, Khammouane and Savannakhet provinces during the survey period. Passive serological surveillance using samples from eight abattoirs in Lao PDR was also performed. Statistically significant (p = 0.05) intra- and inter-provincial differences were noted in a number of the surveys. The success of CSF vaccination via post-vaccination serology was also assessed. The results of the investigations determined that vaccination to prevent CSF infection was insufficient and post-vaccination responses were variable. Phylogenetic and phylogeographic studies to determine the genetic characteristics of Lao PDR and other regional CSF virus isolates are presented in Chapter 6. The 5’-non-coding region and the E2 gene of CSF viruses were investigated to determine genetic relationships between Lao PDR and regional isolates. Genetic typing of all field virus isolates using phylogenetic analysis techniques indicated that all viruses belonged to genogroup 2. Phylogeographic analysis of field viruses revealed a delineation of sub-genogroup allocation on a geographic basis. Members of the sub-genogroup 2.1 originated in Northern and Central regions of Lao PDR. Conversely, members of the sub-genogroup 2.2 originated in Southern and Central regions of Lao PDR. All Vietnamese viruses examined belonged to sub-genogroup 2.2. Phylogenetic analysis indicated that the Vietnamese viruses were largely distinct from Lao and Thai CSF viruses. With the exception of one virus isolate, all Thai viruses also belonged to sub-genogroup 2.2. With the exception of one Vietnamese vaccine virus, all vaccines examined belonged to genogroup 1. A general discussion of the results presented in all chapters, as well as implications for future research into this field, are presented in Chapter 7.