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Bovine viral diarrhoea virus infection is an important viral infection affecting the cattle industry today. The prevalence of this infection in South African feedlots is unknown. Ear notch biopsies were collected from animals entering feedlots which appeared unthrifty, chronic poor doers, and animals entering the hospital pen with respiratory disease for the first time. One thousand and seventy four (1074) samples were collected from the first two categories and 616 samples from animals entering the hospital pen. Samples were processed with routine immunoperoxidase protocol. Serum samples were also collected when possible. The first aim of this study was to determine the prevalence with the use of immunoperoxidase staining on ear notch biopsies. Overall 49 animals tested positive, 43 from the 1074 group and 6 from the 616 group. The prevalence of persistently infected cattle entering the feedlots was determined as 2.9%, which is higher than the rule of thumb that 0.5% of infected animals enter feedlots. Four percent were positive in the group of 1074 animals and one percent in those entering the hospital pen for the first time. It was proposed by the author that persistently infected animals are at a greater risk to develop respiratory disease in the feedlot, but this was not supported by the data collected. There was thus no clear increase in respiratory disease in persistently infected animals. The reliability of the immunoperoxidase stain as a diagnostic method to identify persistently infected animals was also evaluated. This diagnostic method proved to be reliable, but the pathologist needs to be aware of non-specific staining. During the course of the research it became apparent that in some cases mast cells in the dermis stain positive with both DAB and NovaRED stains. Positive staining in keratinocytes and hair follicle epithelium was not present and these cases were proven as negative for persistent infection. The specific cause of positive staining of mast cell granules remains unclear. Only ten positive cases had serum samples on which ELISA tests for antigen and antibody were performed. All tests correlated well with the immunoperoxidase method except in four cases, where the animals were incorrectly diagnosed as positive due to the non-specific staining as described above. Immunoperoxidase staining on ear notch biopsies is thus a reliable diagnostic method to identify persistently infected animals with BVDV, but the pathologist must be aware of non-specific positive staining. / Bees virus diarree infeksie is ‘n belangrike virale infeksie wat die bees industrie van vandag beinvloed. Die prevalensie van die infeksie in Suid Afrikaanse voerkrale is onbekend. Oorknip biopsies is geneem van verdagte diere met aankoms by die voerkraal, chroniese swak beeste en diere wat vir die eerste keer in die hospitaal kraal weens respiratoriese siekte opgeneem is. Een duised vier en sewentig (1074) monsters is van die eerste twee kategoriee geneem en 616 monsters van diere wat in die hospitaal kraal opgeneem is. Monsters is op roetiene wyse vir immunoperoksidase kleuring geprosesseer. Serum monsters is waar moontlik ook versamel. Die eerste doel van die studie was om die prevalensie van permanente besmette draers te bepaal met behulp van immunoperoksidase kleuring op oorknip biopsies. Nege-en-veertig diere in totaal het positief getoets, 43 vanuit die eerste groep en 6 vanuit die tweede groep. Die prevalensie van permanente besmette draers wat in voerkrale opgeneem word is was 2.9% wat hoër is as die verwagte 0.5% wat deur die literatuur aangedui word. Vier persent was positief in die 1074 groep en 1% in die groep wat vir die eerste keer in die hospitaal kraal opgeneem is. Dit is deur die navorser voorgestel dat permanente besmette draers ‘n groter risiko het om met respiratoriese siektes in die hospitaal kraal opgeneem te word, maar dit is nie deur die data bevestig nie. Daar was dus geen verhoging in die teenwoordigheid van respiratoriese siektes in geaffekteerde diere nie. Die betroubaarheid van immunoperoksidase kleuring om permanente besmette diere met BVD te identifiseer is ook geevalueer. Die metode is betroubaar gevind, maar die patoloog moet bewus wees van nie-spesifieke kleuring. Gedurende die navorsing het dit aan die lig gekom dat mastselle in die dermis positief kleur met DAB en NovaRED kleuring. Positiewe kleuring was nie in die epidermis of haarfollikel epiteel teenwoordig nie en die die gevalle was negatief vir permanente besmetting. Die spesifieke rede vir positiewe kleuring in mastselle is steeds onduidelik. Slegs 10 positiewe gevalle het serum monsters gehad vir ELISA teenliggaam en antigeen toetse. Die resultate het goed gekorrelleer met die immunoperoksidase kleuring, behalwe in 4 gevalle waar gevalle verkeerd as positief gediagnoseer is as gevolg van nie-spesifieke positiewe kleuring soos beskryf. Immunoperoksidase kleuring is dus ‘n sensitiewe metode om permanente besmette draers met BVDV te identifiseer, mits die patoloog bewus is van nie-spesifieke kleuring wat mag voorkom. / Dissertation (MMedVet)--University of Pretoria, 2010. / Paraclinical Sciences / unrestricted

Bovine viral diarrhoea virus (BVDV) has emerged as one of the economically important pathogens in cattle populations with a worldwide distribution and causing a complex of disease syndromes. It is a single-stranded RNA virus of the genus Pestivirus in the family Flaviviridae. Two genotypes (1 and 2) of BVDV exist and can be distinguished on the basis of the 5' non-coding region (5' NCR) of the genome using real-time PCR. This technique is more sensitive, specific, less time consuming and has reduced risks of cross contamination of samples compared to a conventional PCR. Limited information exists on BVDV genetic subtypes in South Africa. The aim of this study was to determine the genotypes of BVDV currently circulating in South African feedlots. A total of 279 specimens (219 tissue samples, 59 trans-tracheal aspirates and one blood sample) were collected from dead and living cattle. Pooled homogenates from the same animals were prepared and total RNA was extracted from 200 μl of the homogenates using the RNeasy Mini Kit (Qiagen) as described by the manufacturer. A screening test was performed on the pooled samples and positive pools were investigated individually. The Cador BVDV Type 1/2 RT-PCR Kit (Qiagen, Hilden, Germany) was used for the real-time PCR assay. The PCR was performed on a Lightcycler® V2 (Roche Diagnostics, Mannheim, Germany) real-time PCR machine and the amplified products were detected via fluorescent dyes. The results were read at 530 and 640 nm for BVDV 1 and 2, respectively. Bovine viral diarrhoea virus was detected in a total of 103 samples that included 91 tissue samples, one blood sample and 11 trans-tracheal aspirates. Eighty five of the strains were genotype 1 strains and 18 were genotype 2. These results represent the first documented evidence for the presence of BVDV genotype 2 in South African cattle. / Dissertation (MSc)--University of Pretoria, 2010. / Veterinary Tropical Diseases / unrestricted

Made available in DSpace on 2014-06-11T19:27:17Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-02-26Bitstream added on 2014-06-13T20:35:33Z : No. of bitstreams: 1 alexandrino_b_me_jabo.pdf: 222632 bytes, checksum: 48c6532830e7cdbb18fc1060e2cf6feb (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O presente trabalho teve como objetivo verificar a variação da ocorrência da Rinotraqueíte Infecciosa Bovina (IBR) pela associação com duas doenças virais imunossupressoras: a Diarréia Viral Bovina (BVD) e a Leucose Enzoótica Bovina (LEB), em seis propriedades onde não se adota esquema de vacinação contra essas enfermidades. Amostras de soro sangüíneo foram analisadas no teste de virusneutralização (VN), para constatação de IBR e BVD, e Imunodifusão em Gel de Ágar (IDGA), para a LEB. Foram selecionados cinco rebanhos bovinos, em propriedades localizadas em municípios dos Estados de São Paulo e Minas Gerais, sendo três de exploração leiteira, um de gado de corte e um misto, com animais soropositivos ao BoHV-1, além de um rebanho controle, sem anticorpos contra essa enfermidade. Das 278 amostras analisadas, 54,68% (152/278) foram positivas ao BoHV-1, 69,70% (194/278) ao BVDV-1 e 34,33% (96/278) ao VLEB. Na análise estatística, ao relacionar cada enfermidade com o tipo de exploração do rebanho e a idade dos animais, houve diferença significativa, indicando que estas variáveis são fatores de risco para as enfermidades estudadas. Em relação ao tipo de exploração, os rebanhos leiteiros foram mais suscetíveis ao BoHV-1 e a LEB (81,31% e 49,53% respectivamente, (α = 1 ) enquanto no rebanho de gado de corte o BVDV-1 teve maior ocorrência (94,74%, α = 1). A idade foi fator de risco apenas para o BoHV-1 e a LEB, sendo os animais mais velhos os mais suscetíveis (α = 1). As associações entre o BoHV-1 e o BVDV-1, e o BoHV-1 e a LEB também foram significativas (α = 5 e α = 1 respectivamente), indicando que em rebanhos infectados por BVDV-1 e/ou LEB, a probabilidade de se encontrar o BoHV-1 é maior do que naqueles onde não ocorre essas duas enfermidades. / The present research had as objective to verify the variation of the occurrence of Infectious Bovine Rhinotracheitis (IBR) by association with two viral infections that affect the immune system, Bovine Viral Diarrhoea (BVD) and enzootic bovine leukosis (EBL), in six farms where vaccination against these diseases was not adopted. Serum samples had been analyzed by the virus neutralization (VN) test for IBR and BVD diagnosis, and agar gel immunodiffusion (IDGA) test for EBL diagnosis. Five cattle herds with BoHV-1 seropositive animals had been selected in the states of São Paulo and Minas Gerais, three of them exploiting dairy cattle, one exploiting beef cattle and one exploiting mixed cattle, in addition to a control herd without seropositive animals. From 278 analyzed samples, 54.68% (152/278) reacted to the BoHV-1, 69.70% (194/278) to the BVDV-1, and 34.33% (97/278) to the EBLV. The statistic analysis showed a significant difference (α = 1) in infection occurrence according to the kind of exploitation and the age of the animals. Dairy cattle were more sensitive to the BoHV-1 (81.31%) and to the EBLV (49.53%) and less to BVDV-1 infection (45.79%). Among the beef herds, the major occurrence was BVDV-1 infection (94.74%), followed by BoHV-1(34.19%) and EBLV (3.95%). The age was a risk factor (α = 1) only for BoHV-1 and EBLV. The associations between BoHV-1 and BVDV-1 infections (α = 5) and between BoHV-1 and EBLV infections (α = 1) also indicated that among BVDV-1 and/or EBLV infected herds the probability of finding BoHV-1 is higher than among herds where these two infections does not occur.

Orientador: Samir Issa Samara / Banca: Maria da Gloria Buzinaro / Banca: Fumio Honma Ito / Resumo: O presente trabalho teve como objetivo verificar a variação da ocorrência da Rinotraqueíte Infecciosa Bovina (IBR) pela associação com duas doenças virais imunossupressoras: a Diarréia Viral Bovina (BVD) e a Leucose Enzoótica Bovina (LEB), em seis propriedades onde não se adota esquema de vacinação contra essas enfermidades. Amostras de soro sangüíneo foram analisadas no teste de virusneutralização (VN), para constatação de IBR e BVD, e Imunodifusão em Gel de Ágar (IDGA), para a LEB. Foram selecionados cinco rebanhos bovinos, em propriedades localizadas em municípios dos Estados de São Paulo e Minas Gerais, sendo três de exploração leiteira, um de gado de corte e um misto, com animais soropositivos ao BoHV-1, além de um rebanho controle, sem anticorpos contra essa enfermidade. Das 278 amostras analisadas, 54,68% (152/278) foram positivas ao BoHV-1, 69,70% (194/278) ao BVDV-1 e 34,33% (96/278) ao VLEB. Na análise estatística, ao relacionar cada enfermidade com o tipo de exploração do rebanho e a idade dos animais, houve diferença significativa, indicando que estas variáveis são fatores de risco para as enfermidades estudadas. Em relação ao tipo de exploração, os rebanhos leiteiros foram mais suscetíveis ao BoHV-1 e a LEB (81,31% e 49,53% respectivamente, (α = 1 ) enquanto no rebanho de gado de corte o BVDV-1 teve maior ocorrência (94,74%, α = 1). A idade foi fator de risco apenas para o BoHV-1 e a LEB, sendo os animais mais velhos os mais suscetíveis (α = 1). As associações entre o BoHV-1 e o BVDV-1, e o BoHV-1 e a LEB também foram significativas (α = 5 e α = 1 respectivamente), indicando que em rebanhos infectados por BVDV-1 e/ou LEB, a probabilidade de se encontrar o BoHV-1 é maior do que naqueles onde não ocorre essas duas enfermidades. / Abstract: The present research had as objective to verify the variation of the occurrence of Infectious Bovine Rhinotracheitis (IBR) by association with two viral infections that affect the immune system, Bovine Viral Diarrhoea (BVD) and enzootic bovine leukosis (EBL), in six farms where vaccination against these diseases was not adopted. Serum samples had been analyzed by the virus neutralization (VN) test for IBR and BVD diagnosis, and agar gel immunodiffusion (IDGA) test for EBL diagnosis. Five cattle herds with BoHV-1 seropositive animals had been selected in the states of São Paulo and Minas Gerais, three of them exploiting dairy cattle, one exploiting beef cattle and one exploiting mixed cattle, in addition to a control herd without seropositive animals. From 278 analyzed samples, 54.68% (152/278) reacted to the BoHV-1, 69.70% (194/278) to the BVDV-1, and 34.33% (97/278) to the EBLV. The statistic analysis showed a significant difference (α = 1) in infection occurrence according to the kind of exploitation and the age of the animals. Dairy cattle were more sensitive to the BoHV-1 (81.31%) and to the EBLV (49.53%) and less to BVDV-1 infection (45.79%). Among the beef herds, the major occurrence was BVDV-1 infection (94.74%), followed by BoHV-1(34.19%) and EBLV (3.95%). The age was a risk factor (α = 1) only for BoHV-1 and EBLV. The associations between BoHV-1 and BVDV-1 infections (α = 5) and between BoHV-1 and EBLV infections (α = 1) also indicated that among BVDV-1 and/or EBLV infected herds the probability of finding BoHV-1 is higher than among herds where these two infections does not occur. / Mestre

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal.

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal