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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
301

Galvijų ir kiaulių genotipo įtaka mineralinių medžiagų kiekiui mėsoje ir jų koreliacija su mėsos kokybe / Cattle and pigs genotype’s influence on the mineral content in meat and it’s correlation with meat’s quality

Valaitienė, Vilma 18 June 2014 (has links)
Darbo tikslas – nustatyti mineralinių medžiagų kiekį skirtingų veislių galvijų ir kiaulių mėsoje bei jų koreliaciją su mėsos kokybės rodikliais. Darbo uždaviniai: 1. Tirti ir įvertinti skirtingų veislių kiaulių ir jų derinių bei skirtingų veislių galvijų ilgiausiojo nugaros raumens cheminę sudėtį ir technologines savybes. 2. Nustatyti skirtingų veislių kiaulių ir galvijų ilgiausiame nugaros raumenyje esantį mineralinių medžiagų kiekį (Na, Mg, Ca, Fe, Ni, Cu, Zn, Ba). 3. Nustatyti tirtų mineralinių medžiagų kiekio ryšį su mėsos kokybės rodikliais. Darbo naujumas. Mėsinių galvijų ir kiaulių mėsoje mineralinių medžiagų kiekio, priklausomai nuo veislės, duomenys yra labai riboti, o kai su kuriomis veislėmis tokie tyrimai išvis nevykdyti. Nustatytas svarbių žmonių sveikatingumui mineralinių medžiagų kiekis, skirtingų genotipų galvijų ir kiaulių mėsoje, šeriant ir auginant gyvulius vienodose sąlygose. Apskaičiuota mineralinių medžiagų kiekio koreliacija su mėsos kokybės rodikliais. Praktinė reikšmė. Atlikti mėsos kokybės tyrimai nustatant mikro- ir makro- elementų koncentracijas įvairių veislių galvijų ir kiaulių mėsoje ir jų ryšio nustatymas su mėsos kokybės rodikliais, yra reikšmingi vertinant mėsos maistinę vertę žmonių mityboje. Maistinių medžiagų kiekis liesoje mėsoje gali skirtis didesniu mastu nei kituose maisto produktuose, dėl gyvulio genetinių ar technologinių savybių. Tikslus nustatymas mikro ir makro elementų, auginant ir šeriant gyvulius vienodomis sąlygomis, sąlygos... [toliau žr. visą tekstą] / The aim of the research – to determine the mineral content in various breeds‘ cattle and pigs meat and its‘ correlation with meat quality indexes. Tasks of the research: 1. To analyse and estimate chemical composition and technological qualities of various different breeds‘ and derivatives‘ pigs and cattle musculus longissimus dorsi. 2. To estimate the mineral content (of Na, Mg, Ca, Fe, Ni, Cu, Zn, Ba) that various breeds‘ pigs and cattle musculus longissimus dorsi contain. 3. To estimate the connection between analysed minerals and indexes of meat quality. Originality of the research. The amount of micro- and macro-elements in cattle and pig meat various according its genotype. The material of such type research are very limited. The amount of minerals in different genotypes‘ cattle and pigs meat was determined after their feeding and keeping in standardised conditions. A correlation of minerals and meat quality indexes was estimated. Practical significance. The fulfilled meat qualitys‘ research determining the concentrations of micro- and macro- element amounts in various breeds‘ cattle and pig meat is significant while evaluating nutritional meats‘ value in human nutrition. The amount of nutrients in low-fat meat might differ from other processed food by a major extent because of animals‘ genetic and technologic characteristics. A precise estimation of micro- and macro- elements, in animals that were held and fed in standardised conditions meat, is going to determine a... [to full text]
302

Microbial Programming of the Neonatal Pig

2013 July 1900 (has links)
Microbial succession, composition and ecological distribution within the gastro-intestinal tract are critical areas of study since commensal bacteria have been shown to affect animal health and development. A series of experiments were conducted to determine whether altered microbial succession in neonatal animals would modulate the development and health of pigs later in life. An initial experiment in conventional pigs was conducted to establish the early postnatal microbial succession profile and to identify early colonizing bacterial species. Culture-independent analysis of digesta and mucosal microbiota showed distinct variation between the proximal and distal gastro-intestinal tract (GIT) indicating that fecal or distal gut profiles cannot be used to predict succession in the upper GIT. Temporally, Clostridium spp. were found to be most prevalent in the GIT microbiota of the neonatal pig up to 0.5 d of age, accompanied by a high abundance of Escherichia and Shigella spp. These genera were transiently displaced by Streptococcus spp. followed by a preponderance of Lactobacillus spp. between 3 and 20 d of age. Subsequently, a “snatch-farrow” model was employed to modulate early postnatal microbial succession and investigate the effects on postweaning microbial composition. Pigs were collected into sterile towels directly from the vaginal canal and transferred to a sterile isolator environment for the first 4 days. Pigs were either inoculated with sow feces or not at 1 d of age resulting in significant differences in fecal microbial profile at 4 days of age, prior to removal from isolators. Analysis using terminal restriction fragment length polymorphisms (TRFLP) of intestinal microbiota at 28 d of age did not show significant clustering or variation in diversity indices for either group during the 4-d postnatal isolator phase. However, enumeration of selected taxa using quantitative PCR did indicate significant treatment differences in postweaning microbiota. Despite these results, this approach was rejected for further use as the protocol provided only moderate control of early postnatal colonization and variation and unpredictability of the timing of natural farrowing contributed to significant litter effects. Finally, a gnotobiotic monoassociation model was used investigate the effects of modulating early postnatal microbial succession on postweaning physiology, microbial composition and mucosal gene expression. Twenty-four cesarean-section derived piglets were monoassociated for the first 4 days of life with either L. mucosae (L), S. infantarius (S), C. perfringens (C) or E. coli (E). Pigs from treatments E and L animals showed the highest growth rate during the conventional rearing period (7-28 d of age). Monoassociation with different bacterial species during the first 4 d of life resulted in significant changes in postweaning microbial composition in small intestine and colon as assessed by quantitative PCR, although TRFLP did not identify unique clustering by treatment or variation in diversity. L. mucosae was the only inoculant species with significant variation, with a reduction in the colonic mucosa at 28 days of age. Monoassociation with L. mucosae was also associated with increased nutrition related gene expression in small intestine. Pigs monoassociated with E. coli had low expression of microbial sensing (TLR2 and 4), NFkappaB complex genes and mucins at 28 d of age. This study clearly showed that controlled early microbial succession in neonatal pigs altered post-weaning commensal microbiota composition, postweaning physiology and host gene expression in small and large intestine. The findings suggest the importance of peri-natal management and feeding strategies in promoting postweaning health and performance.
303

Erarbeitung von Methoden und Strategien zur Prävention des Eintrages von Salmonellen in die Nahrungskette auf der Ebene der Primärproduktion beim Schwein

Yilmaz, Muhammed 20 June 2011 (has links) (PDF)
Ziel der vorliegenden Arbeit war es, Methoden und Strategien zu entwickeln, die auf der Ebene Primärproduktion Schwachstellen im Bezug auf das Vorkommen von Salmonellen beim Schwein schon möglichst vor der Schlachtung aufdecken, um gezielte Maßnahmen zur Verhinderung der Einschleppung und Verbreitung sowie zur Bekämpfung von Salmonellen im Schweinebestand zu ergreifen. Die Notwendigkeit dazu ergibt sich daraus, dass eine Salmonellen-Infektion im Schweinebestand in den meisten Fällen nicht mit krankheitsbedingten Symptomen verbunden ist, was dazu führt, dass diese Keime in der Herde meist unerkannt bleiben und mit infizierten Schweinen sowie Ferkeln von Betrieb zu Betrieb gelangen (BFR 2009a). Solche Tiere stellen bekanntlich auch die Ursache eines möglichen Eintrages in die Lebensmittelkette dar (PIOTOWSKI 2008). Die Ergebnisse einer EU-weiten Studie zu Salmonellen in Haltungsbetrieben mit Zuchtschweinen zeigten, dass in den meisten EU Mitgliedsstaaten diese Erreger anzutreffen sind und in allen Mitgliedsstaaten mit intensiver Schweineproduktion nachgewiesen werden konnten (EFSA 2009). Die Studie wurde nach einem von der EU vorgegebenem Studienplan zwischen dem 01. Januar und 31. Dezember 2008 durchgeführt. Dabei wurden in jedem Mitgliedsstaat mindestens 80% der Zuchtschweine erfasst und die Untersuchungen in Betrieben mit mindestens 50 Zuchtschweinen durchgeführt (HARTUNG 2010). Die Ergebnisse der Untersuchungen in der Bundesrepublik Deutschland zur EU-weiten Grundlagenstudie machten deutlich, dass von 2010 untersuchten Kotproben aus 201 Schweinebeständen 125 Proben (6,2%) positiv auf Salmonellen getestet wurden. Als positiv für Salmonella spp. erwiesen sich 45 Schweinebestände (22,4%). In diesen Betrieben waren in den meisten Fällen nur eine (15 Betriebe) bis zwei (elf Betriebe) von zehn untersuchten Kotproben positiv, was darauf hindeutet, dass nur wenige Tiere in den betroffenen Beständen Salmonellen ausscheiden (HARTUNG 2010). Mit der seit März 2007 geltenden „Verordnung zur Verminderung der Salmonellenverbreitung durch Schlachtschweine“ (Schweine-Salmonellen-Verordnung), wurde die europäische Verordnung zur Zoonosenbekämpfung VO EG 2160/2003 im Hinblick auf die Salmonellenproblematik bei Mastschweinen in Deutschland umgesetzt. Die mit dieser Verordnung ermittelten serologischen Befunde haben einen retrospektiven Charakter und erreichen den Schweinezüchter meist Wochen nach der Schlachtung. Daher können diese Befunde keinen Hinweis über die aktuelle Salmonellen-Situation im Schweinebestand geben. Ziel der Untersuchungen nach der SSV (Schweine-Salmonellen-Verordnung) ist nicht die Identifikation Salmonellen-infizierter Einzeltiere sondern, die Kategorisierung der Schweinemastbetriebe, um Schlachttiere aus Salmonellenbelasteten Betrieben gesondert dem Schlachtprozess zu unterziehen, die zur Kontrolle des Erfolgs eines Hygienemanagements auf Herdenbasis mittels der zugelassenen serologischen Tests erfolgen. Für die Untersuchung von Einzeltieren sind diese Tests aufgrund ihrer Konzeption nicht geeignet (RÖSLER 2006). Es fällt dem Inhaber eines Endmastbetriebes meist schwer die Schwachstellen im eigenen Schweinemastbetrieb aufzudecken und diese zu beheben. Schließlich wird in diesem Zusammenhang mit dem erwähnten serologischen Vorgehen eine größere Bedeutung dem Monitoring von Salmonellen im Bestand beigemessen, als der Prävalenz und das schnelle Erkennen von Veränderungen. Zur Prävention des Eintrages von Salmonellen in die Nahrungskette fehlen gezielte Methoden und Strategien, welche zeitnah dem Landwirt einen Hinweis über die aktuelle Situation im Schweinebestand geben können. Ein wirkungsvolles Vorgehen zur Verhinderung des Eintrages von Salmonellen in die Nahrungskette („Food Chain“) ist somit nur bei weitgehender Einbindung der Primärproduktion in das Vorgehen möglich, dazu muss aber der landwirtschaftliche Betrieb wissen welche Maßnahmen zur Eigenkontrolle er sinnvoller Weise bei einem vertretbaren Kostenansatz durchführen kann. Um dies zu ermöglichen, musste zuerst eine Analyse der Schwachstellen und die Identifizierung von effektiven Probenahmestellen in ausgewählten, unterschiedlich konzipierten Betrieben erfolgen. Gleichzeitig musste eine Nachweismethode entwickelt werden, die mit einer begrenzten Menge Probenmaterial von verschiedenen Probenahmeorten im Betrieb einen weitgehend sicheren und empfindlichen Salmonellennachweis ermöglicht. Dies geschah in zwei Schritten, zuerst in Langzeituntersuchungen ausgewählter Betriebe, gefolgt von einem zweiten Schritt zur Verizifierung der aus diesen Untersuchungen resultierenden Beprobungsstrategie. Zunächst wurden in sogenannten Langzeituntersuchungen verschiedene Probenpunkte mit fünf standardisierten Nachweisverfahren auf vier verschiedenen Schweinemastbetrieben vergleichend untersucht. Mit den Ergebnissen wurde die effektivste Nachweismethode sowie die aus praktischer Sicht anwendbaren Probennahmepunkte ermittelt. Mit den sich anschließenden sogenannten Querschnittsuntersuchungen konnten die ermittelten Probennahmepunkte und Nachweismethoden auf acht zufällig ausgewählten Schweinebetrieben angewandt und bestätigt werden.
304

Qualitätsparameter in der SB-Vermarktung

Barbe, Carsten, Westphal, Karsten 02 January 2012 (has links) (PDF)
Untersucht wurden die Einflussfaktoren auf den Tropfsaftverlust von Schweinefleisch in Verpackungen zur Selbstbedienung. Dabei wurden die Bag-Methode und die EZ-Driploss-Methode zur Bestimmung des Tropfsaftverlustes verglichen. Die Auswertung der Daten der Leistungsprüfung von 3.396 Reinzuchttieren und 802 Kreuzungstieren zeigten, dass die Qualität von SB-Fleisch hinsichtlich des Safthaltevermögens anhand der Fleischqualitätsparameter pH-Wert, Py-Wert, Leitfähigkeit und Farbhelligkeit vorhergesagt werden kann. Einen Einfluss auf die Qualität haben u. a. die genetische Konstruktion und die Jahreszeit.
305

Ersatz von Soja in der Schweinefütterung

Alert, Hans-Joachim 21 February 2012 (has links) (PDF)
Der Bericht beschreibt Methoden und Ergebnisse von Fütterungsversuchen mit Trockenschlempe und Rapsextraktionsschrot. Im Lehr- und Versuchsgut Köllitsch wurden über Futterabrufstationen Sauentragefutter und Schweinemastfutter ohne Sojaextraktionsschrot eingesetzt. Das Tragefutter enthielt 6 oder 10 Prozent Weizentrockenschlempe bzw. 10 Prozent Rapsextraktionsschrot. Die Reproduktionsleistungen der Sauen wurden dadurch nicht nachteilig beeinflusst. Durch den Einsatz von 10 Prozent Weizentrockenschlempe wurden je Sau etwa 1 Euro und durch den Einsatz von Rapsextraktionsschrot etwa 2 Euro je Sau eingespart. In der Anfangsmast wurden 20 Prozent Weizentrockenschlempe bzw. 20 Prozent Rapsextraktionsschrot eingesetzt, in der Endmast jeweils 16 Prozent dieser Nebenprodukte. Trockenschlempe war im Gegensatz zu Rapsextraktionsschrot als alleiniges Eiweißfuttermittel in der Schweinemast geeignet. Dadurch konnten die Futterkosten je Schwein um 4 Euro gesenkt werden.
306

The prevalence of potential recombinant viral vectors in the feral pig population of Cape York Peninsula

Hokanson, C. L. Unknown Date (has links)
No description available.
307

Characterising and Mapping Porcine Endogenous Retroviruses (PERVs)

Lee, Jun Heon January 2001 (has links)
The initial focus of this PhD project was on comparative gene mapping. Comparative gene mapping is facilitated by consensus PCR primers which amplify homologous gene fragments in many species. As a part of an international co-ordinated programme of comparative mapping in pigs, 47 CATS (Comparative Anchor Tagged Sequence) consensus primer pairs for loci located on human chromosomes 9, 10, 20, and 22, were used for amplifying homologous loci in pigs. After optimization of PCR conditions, 23 CATS products have confirmed by comparison with homologous sequences in GenBank. A French somatic cell hybrid panel was used to physically map the 6 porcine CATS products distinguishable from rodent background product, namely ADRA1A, ADRA2A, ARSA, GNAS1, OXT and TOP1. Of these, the map location of ADRA1A and OXT showed inconsistency with the previously recognised conserved relationship between human and pig. The other four loci mapped to positions consistent with known syntenic relationships. Despite low levels of polymorphism, frequently indistinguishable rodent and porcine products in somatic hybrids and some confusion of identity of gene family members, these CATS primers have made a useful contribution to the porcine-human comparative map. The focus of the project then changed to genetic and molecular characterisation of endogenous retroviruses in pigs and their relatives. Pigs are regarded as a potentially good source of organs and tissues for transplantation into humans. However, porcine endogenous retroviruses have emerged as a possible problem as they can infect cultured human cells. Two main types of pig retrovirus, determined by envelope protein, PERV-A and PERV-B, are widely distributed in different pig breeds and a third less common type, PERV-C, has also been recognised. Endogenous retroviruses were analyzed from the Westran (Westmead transplantation) inbred line of pig, specially bred for biomedical research. Thirty-one 1.8 kb env PCR product clones were sequenced after preliminary screening with the restriction enzymes KpnI and MboI. Five recombinant clones between A and B were identified. 55% of clones (17/31) sequenced had stop codons within the envelope protein-encoding region, which would prevent the retrovirus from making full-length envelope protein recognizable by cell-surface receptors of the virus. The endogenous viruses were physically mapped in Westran pigs by FISH (Fluorescence In Situ Hybridisation) using PERV-A and PERV-B envelope clones as probes. Preliminary FISH data suggest that there are at least 22 PERVs (13 PERV-A and 9 PERV-B) and the chromosomal locations of these in the Westran strain are quite different from European Large White pigs. The sequences and mapping results of inbred Westran pig suggest that there are relatively few PERV integration sites compared with commercial pigs and further that a large proportion of clones are defective due to premature stop codons in the envelope gene. To investigate the relationship of endogenous retroviruses in peccaries and pigs, a set of degenerate primers was used to amplify peccary retroviral sequences. The sequences of two putative retroviral clones showed close homology, albeit with a 534 bp deletion, to mouse and pig retroviral sequences. Also, four non-target sequences were amplified from peccary with the degenerate retroviral primers. They are a part of the peccary cofilin gene, a SINE, and a sequence containing a microsatellite. The peccary endogenous retroviral sequences are significant in that they are the first such sequences reported in peccary species and repudiate old claims in the literature that peccaries do not have C-type retroviral sequences.
308

Therapeutic effect of Interleukin-4 and Interleukin-1 Receptor Antagonist in Actinobacillus pleuropneumoniae challenged pigs

Khan, Shamila January 2005 (has links)
Immunological stressors, in the form of clinical and sub-clinical disease are currently controlled using both prophylactic antibiotics in-feed, and therapeutic antibiotic treatment. Respiratory disease, primarily Actinobacillus pleuropneumoniae (App) infection, is recognised as a major factor causing reduced productivity in pigs. This thesis reports investigations into the use of novel immunomodulators in particular Interleukin 4 (IL-4) and Interleukin 1 receptor antagonist (IL-1ra) as alternatives to antibiotics to treat App infection. Immunological and molecular biological assays were used to investigate and accumulate data. An in vitro study undertaken to find potential anti-inflammatory substances, revealed that Interleukin 8 (IL-8) mRNA production stimulated by PMA or LPS in whole pigs' blood was suppressed by IL-4. IL-1ra also suppressed stimulated IL-8 mRNA production by heat killed App bacteria (KB) in vitro. An acute LPS challenge in pigs in vivo however, showed no variation in illness or weight loss between pigs treated prophylactically with anti-inflammatory substance (IL-4 and IL-1ra) and saline treated pigs. The use of plasmids as a delivery system for anti-inflammatory substance did not show promise since it did not enhance growth or prolong the expression of the substances in the pigs. However, in the chronic App challenge model IL-4 and IL-1ra administered prophylactically in vivo showed an ability to improve growth. The therapeutic administration of IL-4 and IL-1ra to App challenged pigs showed no difference in pigs' growth, regardless of the treatment or control administered. To conclude, IL-4 and IL-1ra showed promise when administered prophylactically and improved growth and abrogated disease under conditions of App challenge. However when IL-4 and IL-1ra where administered therapeutically they did not perform as well. Moreover these compounds have potential as a commercial application to reduce the growth reduction caused by disease such as App.
309

Quality assurance for pig carcasses: a study of bacterial contamination at domestic abattoirs in South Australia

Skull, John January 2004 (has links)
This study of four domestic abattoirs in South Australia with Quality Assurance programmes in place established the size of bacterial populations that could be expected on pig carcasses on entry to abattoir dressing floors at pre-evisceration, the extent of contamination occurring during carcass dressing, and the effect of chilling on these populations. Analysis was conducted for salmonellae, Escherichia coli, Total Viable Count, and pseudomonads. Exterior swabbing was compared to swabbing of corresponding interior sites which are sterile initially. The interior swabbing sites were found to be a more reliable measure of contamination during the dressing process than the swabbing of already contaminated exterior sites. During the identification of some of the points of carcass contamination, the effectiveness of end-of-work foam cleaning programmes used at abattoir dressing floors and their relationship to the potential for airborne contamination of carcasses was examined and found to be positive. Operators' work tools and hands were identified as sources of interior carcass contamination combined with failure of operators to adhere to Standard Operating Procedures (SOPs) during carcass dressing, especially those related to hand and forearm washing at appropriate times. Foot-operated full-immersion hot water units for operators' knives and steels were designed and installed at two abattoirs to give operators access to physically and biologically clean work tools throughout carcass dressing. / PhD Doctorate
310

Classical Swine Fever in the Lao Peoples' Democratic Republic: Virological, Epidemiological and Clinical Studies

Blacksell, Stuart Dean Unknown Date (has links)
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.

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