Master of Science / Department of Diagnostic Medicine/Pathobiology / Raymond R. R. Rowland / Pestiviruses such as classical swine fever virus (CSFV) and bovine viral diarrhea virus (BVDV) are some of the most economically important livestock diseases in the world. The antigenic similarities between members of the pestivirus genus allow for both BVDV and CSFV to infect swine. Infections with heterologous pestiviruses in swine can interfere with diagnostic tests for CSFV. The identification of cross-reactive and cross-neutralizing epitopes between CSFV and BVDV for the development of improved diagnostics and vaccines that allow for the differentiation of infected animals from vaccinated animals (DIVAs) are necessary to accurately detect and control CSFV. The overall goal of this research was to identify epitope regions recognized by antibodies that can differentiate between CSFV and BVDV. The approach was to use serum neutralization assays to confirm the presence of neutralizing antibodies to BVDV in swine serum collected from animals immunized with one of three separate Alphavirus vaccine constructs: BVDV-1b, CSFV E2, and CSFV E[superscript]rns. Results showed that animals immunized with the Alphavirus BVDV-1b construct had high neutralizing titers against BVDV-1a and animals immunized with Alphavirus CSFV E2 and E[superscript]rns constructs had low, but detectable, neutralizing activity. Polypeptide fragments of CSFV and BVDV E2 were then expressed in E. coli and purified using affinity chromatography. Serum from a pig immunized with the CSFV E2 Alphavirus construct was tested against two fragments of CSFV E2, 2/4 and 4/4, and four fragments BVDV E2, 1/4, 2/4, 3/4, and 4/4, using western blot analysis. Reactivity to fragments CSFV E2 2/4 and 4/4 and BVDV E2 1/4 and 4/4 was observed. The results of this study identified CSFV amino acid positions 774 through 857 and BVDV amino acid positions 783 through 872 as the regions that contain the epitopes recognized by cross-reactive antibodies between BVDV and CSFV E2. These results provide more specific sequence regions to improve CSFV diagnostic assays and DIVA vaccines.

Bovine viral diarrhea virus (BVDV) is an important viral pathogen affecting all ages of cattle, resulting in significant economic losses worldwide. BVDV infection is associated with a diverse array of symptoms including gastrointestinal disorder, respiratory distress, fetal malformation, stillbirth, abortions, and mucosal disease (MD). Transplacental infections of fetuses between 42 and 125 days of gestation can result in immune-tolerance and the surviving fetuses become persistently infected (PI). PI animals are major reservoir of BVDV and it becomes problematic to control the disease. The objectives of this dissertation were to: 1) develop a cost-effective testing scheme to detect BVDV PI animals from exposed herds, 2) characterize two virulent BVDV-2 Mississippi isolates associated with severe hemorrhagic diseases, and 3) perform phylogenetic analysis based on sequences of 5'UTR, E2, and NS5B regions. First, we developed a BVDV testing scheme by combining pooled real-time RT-PCR with antigen capture enzyme-linked immunosorbent assay (ACE) to screen cattle herds. From positive pools individual positives were identified using ACE. Data from a three year period indicated that 92.94% PI animals were infected with BVDV-1, 3.53% with BVDV-2, and 3.53% with both BVDV-1 and BVDV-2. Analysis of the 5'UTR of 22 isolates revealed the predominance of BVDV-1b followed by BVDV-2a. Second, two virulent BVDV isolates, M10-3432 and M10-5347, were successfully recovered from an adult beef breeding cow and feedlot calf respectively. When compared to the reference strain BVDV-2 125c, five and three unique amino acids in E2 regions were different from M10-5347 and M10-3432 respectively. Phylogenetic analysis of E2 region grouped both Mississippi isolates in BVDV-2a, a subtype containing high virulent strains. M10-3432 was clustered with high virulent strain 890 while M10-5347 was clustered with high virulent strain CD87. Third, we compared the phylogenetic analyses of BVDV based on the sequences of 5'UTR, E2, and NS5B at either nucleotides or amino acids level. Although slight differences were observed, the virulent BVDV isolates were consistently classified into BVDV-2a cluster regardless of region of sequences used. Furthermore, phylogenetic tree constructed using combined two or more regions had higher posterior probability and bootstrap value than phylogenetic trees constructed using a single region

Bovine Viral Diarrhea Virus (BVDV) is a significant disease causing agent with major economic impact on the cattle industry, causing both productive and reproductive losses. One reason for its widespread distribution is that the majority of all BVDV infections occur without clinical signs, leaving most cases of BVDV undetected in cow herds. BVDV occur as cytopathic (CP) or non-cytopathic (NCP) biotypes, classified according to whether or not they produce visible changes in cell culture. CP BVDV biotype but not NCP biotype is implicated in the induction of apoptosis in vivo. The interaction of BVDV with its host has several unique features, most notably the capacity to infect its host either transiently or persistently. The pathogenesis of the disease caused by BVDV is complicated and interaction between BVDV and the host are poorly understood. The overall goal of this research is to identify mechanistic pathways that govern the outcome of BVDV infection in susceptible host cells. Specific aspects of this goal is to understand BVDV biotypes-induced changes on cellular proteome, cell death and survival mechanisms used by BVDV biotypes in apoptosis pathway, interactions of BVDV NS3 viral protein with host cellular proteins and how BVDV cell entry and infection interfere with an early step of professional antigen presentation, antigen uptake. The results of this work showed, for the first time, the successful use of proteomics in studying BVDV-host interactions in a comprehensive approach. Using the Gene Ontology and systems biology analysis we identified biotype-related differences in significant biological pathways and functions. Also, using a proteomics approach, we identified multiple critical cellular proteins that interact with CP NS3 viral protein at multiple stages of CP BVDV replication cycle. This project provides insight into the cellular pathways and functions involved in the viral cytopathogenicity of CP BVDV biotype. In addition, our data not only confirmed the previous observations on the critical involvement of the intrinsic pathway of apoptosis in CP BVDV infection, it also identified multiple mitochondrial and antioxidant proteins contributing to this pathway. Finally, we show that BVDV exploit selective antigen uptake mechanisms in professional antigen presenting cells monocytes during viral entry.

Doctor of Philosophy / Department of Diagnostic Medicine/Pathobiology / Daniel U. Thomson / Bovine viral diarrhea virus (BVDV) has emerged as one of the most important infectious diseases in cattle. One particular important manifestation, after successfully establishing an in utero infection of the fetus during the first trimester, is the development of a persistently-infected BVDV (PI-BVDV) calf. Persistently infected BVDV animals are a continuous source of virus and can shed the virus in virtually all secretions and excretions, including nasal discharges, saliva, semen, urine, tears, milk, and, to a lesser extent, feces. The objectives of this research were to determine: 1) the effects of short term exposure (13 – 18 days on feed (DOF)) to PI-BVDV feeder cattle; 2) the outcome of testing and removing PI-BVDV feeder calves at time of feedlot arrival on health, performance, and carcass characteristics; 3) the survival of BVDV on materials associated with livestock production; and 4) characterization of testing and longitudinal prevalences for PI-BVDV beef cattle. Testing and removing PI-BVDV calves at 13 to 18 DOF was too late to remove a morbidity effect due to PI-BVDV exposure. However, mortality, performance, and carcass characteristics were not different in cattle exposed to PI-BVDV cattle. Additionally, there were no harmful outcomes when newly arrived feeder cattle were exposed to a PI-BVDV animal for one to two days following feedlot entry. A non-cytopathic, Type 1b, BVDV was capable of surviving after application to various materials used in livestock production. BVDV tended to survive longer on non-porous materials than porous materials. When in the presence of mucus, BVDV was protected from degradation for longer periods of time than when not in the presence of mucus. There was no difference in overall PI-BVDV prevalence within cattle sampled in 2006 and 2007. Cattle that weighed less than 300 lbs. had a greater likelihood of being PI-positive than cattle with increased weights. Several months of the year had a greater likelihood of having PI-positive animals. Based on operation, cow-calf and stocker operations had a greater likelihood of having PI-positive animals than did feedlot operations.

O objetivo geral desta pesquisa foi avaliar a resposta imune (RI) humoral e celular de bezerros recém-nascidos mediante imunização passiva e ativa, usando como modelo o Vírus da Diarreia Viral Bovina (BVDV) e o Herpesvírus Bovino tipo-1 (BoHV-1). Esta pesquisa foi dividida em duas etapas e seus dados estão apresentados em dois capítulos. Capítulo 1- Acompanhou-se a imunização passiva de bezerros do nascimento até os seis meses de idade e a influência da vacinação materna no período pré-parto nessa resposta. Os animais foram distribuídos em dois grupos experimentais que receberam colostro de mães não imunizadas (G1, n=4) e (G2, n=6) de mães imunizadas no período pré-parto para o BVDV e BoHV-1. A colostragem foi feita pela administração de seis litros de colostro nas primeiras doze horas de vida, distribuídas em duas mamadas. Nesta etapa foi possível verificar: (1) a presença de títulos de ACs neutralizantes apenas no grupo de bezerros que receberam colostro de mães imunizadas, obtendo soroconversão após a mamada de colostro em 2/6 (33%) bezerros para o BVDV e 6/6 (100%) para o BoHV-1; (2) manutenção dos títulos de ACs protetores até os três meses de vida. Em relação a RI celular: (3) observou-se maior proporção de células T auxiliares CD4+ (P=0,05) no grupo de bezerros que receberam colostro de mães imunizadas no período pré-parto; (4) o leucograma dos bezerros demonstrou respostas inflamatórias em alguns momentos desta pesquisa, mais intensa nos animais que ingeriram colostro proveniente de mães nãoimunizadas. Capítulo 2- Acompanhou-se a imunização de bezerros para BVDV e BoHV-1 aos seis meses de idade. Dez bezerros foram distribuídos em dois grupos de bezerros não vacinados (VAC-, n=5) e vacinados para o BVDV e BoHV-1 (VAC+, n=5), as análises foram realizadas antes da imunização aos 180 dias (T0), após a 1°dose aos 210 dias (T1) e após a 2° dose aos 240 dias (T2). Os resultados obtidos para avaliação da RI humoral foram: (1) soroconversão de 2/5 (40%) animais no momento T1 e 3/5 (60%) no T2 para o BVDV; (2) soroconversão em 2/5 (40%) no T1 e 5/5 (100%) no T2 para o BoHV-1. Para a RI celular observou-se: (3) maior expressão de CD25+ pelas subpopulações de linfócitos T gama-delta WC1+ no VAC+, observando-se diferença estatística no momento T1 (P=0,0016). Com base nos resultados obtidos nas duas etapas experimentais desta pesquisa pode-se concluir que a vacinação materna é uma estratégia para melhorar a qualidade do colostro e as repostas imunes humoral e celular dos bezerros para BVDV e BoHV-1; a duração da imunidade materna considerando-se níveis protetores de Acs foi de três meses; os componentes do colostro influenciaram na resposta inflamatória dos bezerros à exposição natural aos patógenos; a vacinação dos bezerros aos seis meses de idade estimulou a resposta imune humoral para BoHV-1 e parcial para BVDV. / The aim of this research was to evaluate the humoral and cellular immune response (IR) of newborn calves by active and passive immunization, using by model the Bovine Viral Diarrhea Virus (BVDV) and Bovine Herpesvirus type-1 (BoHV-1). This research was divided in two stages and the datas are presented in two chapters. Chapter 1: Was followed the passive immunization of calves from birth until six months old and the maternal vaccination influence on pre-partum period on this response. The animals were divided in two experimental groups that received colostrum from unvaccinated mothers (G1, n = 4) and (G2, n=6) from immunized mothers in the pre-partum period to BVDV and BoHV-1. The calves received six liters of colostrums on the first twelve hours of life, divided in two feedings. At this stage was verified: (1) the presence of neutralizing titers antibodies (Abs) only in group of calves that received colostrum from immunized mothers, getting seroconversion after feeding in 2/6 (33%) of calves for BVDV and 6/6 (100%) for BoHV-1, (2) maintenance of Abs titers protectors up to three months of life. In relation to immune cellular response: (3) was observed higher proportion of helper T cells CD4+ (P = 0.05) in the group of calves that received colostrum from immunized mothers during pre-partum; (4) the leukogram of calves showed inflammatory responses in some moments of this research, more intense in animals that ingested colostrums from non-immunized mothers. Chapter 2: Was followed the immunization of calves for BVDV and BoHV-1 at six months old. Ten calves were divided in two groups of calves non-vaccinated (VAC-, n = 5) and vaccinated for BVDV and BoHV-1 (VAC +, n = 5). The analyzes were performed before immunization at 180 days (T0), after the 1st dose at 210 days (T1) and after the 2nd dose at 240 days (T2). The results for evaluation of immune humoral response were: (1) seroconversion 2/5 (40%) animals at the T1 moment and 3/5 (60%) of T2 for BVDV, (2) soroconversion on 2/5 (40 %) in the T1 to 5/5 (100%) at T2 for BoHV-1. For the immune cellular response was observed: (3) increased expression of CD25+ subpopulations of T lymphocytes by gamma-delta WC1+ in VAC+, observing statistical difference in T1 moment (P = 0.0016). Based on the results obtained in the two experimental stages of this research can be concluded that maternal vaccination is a strategy to improve the quality of colostrum and humoral and cellular immune response of calves to BVDV and BoHV-1, the duration of maternal immunity considering protective levels of Abs was three months. The components of colostrum influence the inflammatory response of calves to natural exposure to pathogens. The vaccination of calves at six months old stimulated the humoral immune response to BoHV-1 and partial for BVDV.

Thesis (Ph.D.)--Mississippi State University. College of Veterinary Medicine. / Title from title screen. Includes bibliographical references.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / Calves born persistently infected (PI) with non-cytopathic bovine viral diarrhea virus (ncpBVDV) frequently develop a fatal gastroenteric illness called mucosal disease (MD). From animals affected by MD, both the original virus (ncpBVDV) and an antigenically identical, yet cytopathic virus (cpBVDV) can be isolated. Cytopathic BVDVs are originated from the ncp counterparts by diverse genetic mechanisms, all leading to the expression of the non-structural polypeptide NS3 as a discrete protein. In contrast, ncpBVDVs express only the large precursor polypeptide, NS2-3, which contains the NS3 sequence within its carboxy-terminal half. The investigation of the mechanism leading to NS3 expression in 41 cpBVDV isolates is reported. An RT-PCR strategy was designed to detect insertions within the NS2-3 gene and/or duplication of the NS3 gene two common mechanisms of expression of NS3. RT-PCR amplification revealed insertions in the NS2-3 gene of three cp isolates, being the inserts similar in size to that present in the cpBVDV NADL strain. Sequencing of one such insert revealed a 296 nucleotide sequence, with a central core of 270 putative aminoacid sequence highly homologous (98%) to the NADL insert, a sequence corresponding to the cellular J-Domain gene. Another cpBVDV isolate contained a duplication of the NS3 gene downstream from the original locus. In contrast, no detectable NS2-3 insertions nor NS3 gene duplications were observed in the genome of 37 cp isolates. These results demonstrate that cleavage of NS2-3 without bulk RNA insertions nor NS3 gene duplications seems to be a frequent mechanism leading to NS3 expression and BVDV cytopathology. / Bezerros nascidos persistentemente infectados (PI) com o biótipo não citopático (ncp) do vírus da Diarréia Viral Bovina (BVDV) freqüentemente desenvolvem uma doença gastroentérica fatal, chamada de Doença das Mucosas (DM). Dos animais afetados pela DM é possível isolar o vírus original não-citopático (BVDVncp) e um vírus antigenicamente idêntico, porém citopático (BVDVcp). Os BVDVcps são gerados a partir do vírus original ncp por diversos mecanismos genéticos, que resultam na expressão da proteína não-estrutural NS3 como uma proteína individual. Em contrapartida, os BVDVncp expressam somente a proteína precursora NS2-3, que contém a seqüência da NS3 no seu terço carboxi-terminal. Este trabalho relata a investigação dos mecanismos genéticos associados com a expressão da NS3 em 41 isolados citopáticos de BVDV. Uma estratégia de RT-PCR foi delineada para detectar inserções no gene da NS2-3 e/ou duplicações no gene da NS3, dois mecanismos freqüentes de expressão da NS3. Amplificação do genoma dos 41 isolados por RT-PCR revelou a presença de inserções no gene da NS2-3 em três isolados, de tamanho similar a inserção presente na cepa de BVDVcp NADL. O seqüenciamento da inserção de um isolado revelou uma seqüência de 296 nucleotídeos, com uma região central de 270 nucleotídeos altamente homóloga (98%) com a inserção da cepa NADL, que corresponde a uma seqüência do gene celular J-Domain. Outro isolado de BVDVcp contém uma duplicação do gene da NS3 na direção 3 da sua posição original. Em 37 isolados cp não foram detectadas inserções na NS2-3 ou duplicações da NS3. Esses resultados demonstram que a clivagem da NS2-3 sem a presença de inserções de RNA ou duplicações do gene da NS3 parecem ser mecanismos frequentes de expressão da proteína NS3 e citopatologia no BVDV.

Made available in DSpace on 2014-06-11T19:27:16Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-02-16Bitstream added on 2014-06-13T19:26:13Z : No. of bitstreams: 1 oliveira_mc_me_jabo.pdf: 308908 bytes, checksum: 64bbc47e580df30ef60b342b4c429d6c (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O Vírus da Diarréia Viral Bovina (BVDV) é um dos patógenos mais importantes na pecuária bovina em todo mundo, principalmente por desencadear manifestações clínicas relacionadas à esfera reprodutiva. A infecção em fêmeas gestantes pode resultar em abortamentos, reabsorções embrionárias, mumificações fetais, má formações e nascimento de bezerros fracos além do aparecimento de animais persistentemente infectados e imunotolerantes ao vírus, que são a principal fonte de infecção e disseminação da doença nos rebanhos. Atualmente, a complexidade do diagnóstico e consequentemente a patogenia, estão relacionados às diferenças genotípicas do agente. Por isso, a presente pesquisa teve como objetivo verificar a ocorrência dos genótipos BVDV-1 (Singer) e BVDV-2 (VS-253) em vacas, e respectivos fetos, abatidas em um frigorífico no Estado de São Paulo por meio da análise do soro sanguineo por meio da técnica de virusneutralização. No contexto geral, 52,51% (115/219) das vacas testadas foram reagentes, mas nenhum feto (0/219) reagiu na virusneutralização. Pela análise cruzada conforme a estirpe viral, observou-se que 42% (92/219) das vacas foram reagentes tanto para o genótipo BVDV-1 como para o genótipo do BVDV-2. Por outro lado 4,10% (9/219) reagiram apenas para o genótipo BVDV-1 e 6,39% (14/219) reagiram apenas para o genótipo do BVDV 2. Notou-se portanto que ambas as estirpes estão disseminadas nas regiões estudadas, fato que justifica o emprego de antígenos diferentes para evitar diagnóstico falso-negativo. Por fim, não foi observado qualquer alteração nos fetos que pudessem ser caracterizada como patologia da enfermidade. / The Bovine viral diarrhea virus (BVDV) is one of the pathogens in bovine livestock worldwide most important mainly triggered by clinical manifestations related to the reproductive sphere. The infection in pregnant females may result in abortions, embryonic resorptions, fetal mummification, poor training, birth of weak calves in addition to persistently infected and virus immunotolerant animals, which are the main source of infection and spread of the disease. Currently, the complexity to diagnosis and consequently to the pathogenesis are related genotypic differences that he presents. Therefore, this research aimed to verify the occurrence of BVDV- 1 (Singer) and BVDV-2 (VS-253) genotypes in cows and their respective fetuses slaughtered in a abattoir at the state of São Paulo by analyzing the blood serum using virusneutralization technique. In the general context, 52.51% (115/219) of cows were reagents, but no fetus (0/219) reacted in virusneutralization. After a cross-examination we observed that 42% (92/219) of cows reacted for both BVDV-1 and BVDV-2 genotype. Furthermore 4,10% (9/219) reacted only to the genotype BVDV-1 and 6,39% (14/219) responded only to the genotype 2 of BVDV. It was noted therefore that both strains are widespread in the regions studied, which also justifies the use of different antigens to avoid false-negative diagnosis. Finally, there was no change in fetuses that could be characterized as a pathology of the disease.

O objetivo geral desta pesquisa foi avaliar a resposta imune (RI) humoral e celular de bezerros recém-nascidos mediante imunização passiva e ativa, usando como modelo o Vírus da Diarreia Viral Bovina (BVDV) e o Herpesvírus Bovino tipo-1 (BoHV-1). Esta pesquisa foi dividida em duas etapas e seus dados estão apresentados em dois capítulos. Capítulo 1- Acompanhou-se a imunização passiva de bezerros do nascimento até os seis meses de idade e a influência da vacinação materna no período pré-parto nessa resposta. Os animais foram distribuídos em dois grupos experimentais que receberam colostro de mães não imunizadas (G1, n=4) e (G2, n=6) de mães imunizadas no período pré-parto para o BVDV e BoHV-1. A colostragem foi feita pela administração de seis litros de colostro nas primeiras doze horas de vida, distribuídas em duas mamadas. Nesta etapa foi possível verificar: (1) a presença de títulos de ACs neutralizantes apenas no grupo de bezerros que receberam colostro de mães imunizadas, obtendo soroconversão após a mamada de colostro em 2/6 (33%) bezerros para o BVDV e 6/6 (100%) para o BoHV-1; (2) manutenção dos títulos de ACs protetores até os três meses de vida. Em relação a RI celular: (3) observou-se maior proporção de células T auxiliares CD4+ (P=0,05) no grupo de bezerros que receberam colostro de mães imunizadas no período pré-parto; (4) o leucograma dos bezerros demonstrou respostas inflamatórias em alguns momentos desta pesquisa, mais intensa nos animais que ingeriram colostro proveniente de mães nãoimunizadas. Capítulo 2- Acompanhou-se a imunização de bezerros para BVDV e BoHV-1 aos seis meses de idade. Dez bezerros foram distribuídos em dois grupos de bezerros não vacinados (VAC-, n=5) e vacinados para o BVDV e BoHV-1 (VAC+, n=5), as análises foram realizadas antes da imunização aos 180 dias (T0), após a 1°dose aos 210 dias (T1) e após a 2° dose aos 240 dias (T2). Os resultados obtidos para avaliação da RI humoral foram: (1) soroconversão de 2/5 (40%) animais no momento T1 e 3/5 (60%) no T2 para o BVDV; (2) soroconversão em 2/5 (40%) no T1 e 5/5 (100%) no T2 para o BoHV-1. Para a RI celular observou-se: (3) maior expressão de CD25+ pelas subpopulações de linfócitos T gama-delta WC1+ no VAC+, observando-se diferença estatística no momento T1 (P=0,0016). Com base nos resultados obtidos nas duas etapas experimentais desta pesquisa pode-se concluir que a vacinação materna é uma estratégia para melhorar a qualidade do colostro e as repostas imunes humoral e celular dos bezerros para BVDV e BoHV-1; a duração da imunidade materna considerando-se níveis protetores de Acs foi de três meses; os componentes do colostro influenciaram na resposta inflamatória dos bezerros à exposição natural aos patógenos; a vacinação dos bezerros aos seis meses de idade estimulou a resposta imune humoral para BoHV-1 e parcial para BVDV. / The aim of this research was to evaluate the humoral and cellular immune response (IR) of newborn calves by active and passive immunization, using by model the Bovine Viral Diarrhea Virus (BVDV) and Bovine Herpesvirus type-1 (BoHV-1). This research was divided in two stages and the datas are presented in two chapters. Chapter 1: Was followed the passive immunization of calves from birth until six months old and the maternal vaccination influence on pre-partum period on this response. The animals were divided in two experimental groups that received colostrum from unvaccinated mothers (G1, n = 4) and (G2, n=6) from immunized mothers in the pre-partum period to BVDV and BoHV-1. The calves received six liters of colostrums on the first twelve hours of life, divided in two feedings. At this stage was verified: (1) the presence of neutralizing titers antibodies (Abs) only in group of calves that received colostrum from immunized mothers, getting seroconversion after feeding in 2/6 (33%) of calves for BVDV and 6/6 (100%) for BoHV-1, (2) maintenance of Abs titers protectors up to three months of life. In relation to immune cellular response: (3) was observed higher proportion of helper T cells CD4+ (P = 0.05) in the group of calves that received colostrum from immunized mothers during pre-partum; (4) the leukogram of calves showed inflammatory responses in some moments of this research, more intense in animals that ingested colostrums from non-immunized mothers. Chapter 2: Was followed the immunization of calves for BVDV and BoHV-1 at six months old. Ten calves were divided in two groups of calves non-vaccinated (VAC-, n = 5) and vaccinated for BVDV and BoHV-1 (VAC +, n = 5). The analyzes were performed before immunization at 180 days (T0), after the 1st dose at 210 days (T1) and after the 2nd dose at 240 days (T2). The results for evaluation of immune humoral response were: (1) seroconversion 2/5 (40%) animals at the T1 moment and 3/5 (60%) of T2 for BVDV, (2) soroconversion on 2/5 (40 %) in the T1 to 5/5 (100%) at T2 for BoHV-1. For the immune cellular response was observed: (3) increased expression of CD25+ subpopulations of T lymphocytes by gamma-delta WC1+ in VAC+, observing statistical difference in T1 moment (P = 0.0016). Based on the results obtained in the two experimental stages of this research can be concluded that maternal vaccination is a strategy to improve the quality of colostrum and humoral and cellular immune response of calves to BVDV and BoHV-1, the duration of maternal immunity considering protective levels of Abs was three months. The components of colostrum influence the inflammatory response of calves to natural exposure to pathogens. The vaccination of calves at six months old stimulated the humoral immune response to BoHV-1 and partial for BVDV.

This study was conducted to compare animal performance, presence of skin reactions and immune response following vaccination of beef calves via needle-free (NF) and needle-syringe (NS) vaccination techniques. Spring-born (Study A) and fall-born (Study B) calves were vaccinated against bovine viral diarrhea virus (BVDV) and Clostridium chauvoei (C. chauvoei) via NF and NS vaccination techniques. The parameters measured in this study included body weight (BW), skin reactions and serum antibodies. Animal performance and antibody levels against BVDV and C. chauvoei did not differ between vaccination techniques. However, NF vaccinated calves had a greater frequency of skin reactions when compared to NS vaccinated calves, except for day 42 of Study B. It can be concluded that a needle-free injection device (NFID) can be used effectively to stimulate an immune response without impacting animal performance, but may cause a greater frequency of skin reactions.