Occurrence of seropositive sheep (Ovis aries) to Bovine Leukemia Virus in Brazil

Occurrence of seropositive sheep (Ovis aries) to Bovine Leukemia Virus (BLV) by agar-gel immunodiffusion test (AGID) using the antigen gp51 was surveyed for the period 2005-2007. Samples were collected from sheep in the Brazilian states of Rio Grande do Sul, Paraná, São Paulo, Pernambuco, Maranhão, Pará, Bahia, Mato Grosso, Rondônia, and Acre. Two of 35 (5.7%) flocks were seropositive to BLV, and the rate of seropositive animals was 0.077% (two of 2,592). The two seropositive sheep were female, one 13-month old Santa Inês breed and other of unknown age and breed, both from the state of São Paulo. Distribution of BLV in the ovine population studied proved to be a rare event in Brazil.A ocorrência de ovinos sororreagentes ao vírus da Leucemia Bovina (VLB) pelo teste de imunodifusão em gel de ágar (IDGA) utilizando o antígeno gp51 foi avaliada no período de 2005-2007, em diferentes regiões do Brasil. Amostras foram colhidas de ovinos dos Estados do Rio Grande do Sul, Paraná, São Paulo, Pernambuco, Maranhão, Pará, Bahia, Mato Grosso, Rondônia e Acre. Duas em 35 cabanhas (5,7%) e dois em 2592 ovinos (0,077%) foram soropositivos. Os únicos animais com anticorpos contra o VLB eram fêmeas, uma com 13 meses de idade e da raça Santa Inês e a outra não se conhecia a idade e raça, ambas provenientes do Estado de São Paulo. A distribuição da soropositividade na população estudada demonstrou ser rara a infecção pelo VLB em ovinos no Brasil

Evaluation of the cross virus neutralization against BVDV-1 and BVDV-2 in the diagnosis of bovine viral diarrhea in naturally infected animals

A Diarréia Viral Bovina (BVD) provoca grandes perdas econômicas na pecuária mundial, é causada pelo vírus da diarréia viral bovina (BVDV), vírus que apresenta diversidade genética e antigênica entre as estirpes o que provavelmente influencia no diagnóstico. Com a proposta de verificar a presença de anticorpos, sua mensuração e neutralização cruzada frente quatro estirpes do vírus, amostras de 1500 bovinos não vacinados contra BVDV, sendo 519 de 15 rebanhos do Estado de Minas Gerais (MG), 499 de cinco rebanhos do Mato Grosso do Sul (MS) e 482 de cinco rebanhos de São Paulo (SP), foram testadas pela técnica de virusneutralização (VN) com as seguintes estirpes citopatogênicas: BVDV-1 (NADL estirpe americana e IBSP-11 isolado nacional) e BVDV-2 (VS-253 estirpe americana e IBSP-1020 isolado nacional). Dos 1500 animais, a variação da frequência de sororreagentes ao BVDV foi de 66,07% a 68,67%, ao analisar os diferentes grupos de animais, de acordo com o estado, a maior frequência de anticorpos foi obtida no MS, seguida por MG e SP, independente da estirpe utilizada na VN. O isolado nacional do genótipo 2, IBSP-1020 foi a estirpe que resultou em maior detecção de reagentes em MG e MS, enquanto que em SP foram as estirpes do genótipo 1. A avaliação dos resultados com as quatro estirpes revelou 73,27% (1099/1500) de animais reagentes a pelo menos um dos vírus, enquanto que, 57,60% (864/1500) foram reagentes aos quatro vírus, simultaneamente, ou seja, estes animais produziram anticorpos que reagiram com todas as estirpes em questão. Os títulos de anticorpos variaram de 10, valor mínimo de detecção da prova, a 5120, sendo que a maior parte dos animais apresentou títulos entre 40 e 160, os títulos observados nos animais de SP foram mais baixos com relação aos animais dos outros estados. A avaliação dos títulos de anticorpos de cada animal, comparando o resultado das estirpes duas a duas, revelou diferença na maioria das situações. Conclui-se que, houve alta frequência de ocorrência de bovinos reagentes ao BVDV, que variou de acordo com o sistema de criação e manejo dos rebanhos. Além disso, a utilização de mais de uma estirpe viral, independente do genótipo ou do local de origem do isolado, aumentou a sensibilidade de detecção de animais sororreagentes na VN. Foi evidenciada neutralização cruzada entre todas as estirpes estudadas. Os resultados reforçam a importância de selecionar estirpes representativas das regiões a serem estudadas para inclusão na VN, visando aumentar a sensibilidade do diagnóstico.The bovine viral diarrhea (BVD) causes great economic losses in livestock worldwide, is caused by bovine viral diarrhea virus (BVDV), which presents genetic and antigenic diversity among strains which probably influences the serological diagnosis. For the proposal to verify the presence and titers of antibodies and cross-neutralization against four strains of virus, samples from 1,500 bovines naturally infected with BVDV, from the States of Minas Gerais (MG), Mato Grosso do Sul (MS) and São Paulo (SP) were tested by the virus-neutralization test (VN), against four cytopathic strains: BVDV-1 (NADL - American strain and IBSP-11 Brazilian isolate) and BVDV-2 (VS-253 - American strain and IBSP-1020 - Brazilian isolate). Of the 1,500 animals, the range from 66.07% to 68.67%, were reactive to BVDV, and the increased frequency of antibodies was obtained in the state of MS, followed by MG and SP, independent of the BVDV strain used in the VN. The national isolate of the genotype 2, IBSP-1020 strain showed highest detection of reagents in MG and MS states, while in SP were the strains of genotype 1. The results with the four strains showed that 73.27% (1,099/1,500) of animals positive to at least one virus, whereas 57.60% (864/1,500) were simultaneously reactive to the four viruses, in other words that is, these animals produced antibodies that cross reacted against all strains in question. The titers of antibodies ranged from 10, the minimum value of detection of VN, to 5120, and that most animals were between 40 and 160 titers. In comparison of antibodies titers among states was observed that animals in SP presented lowest antibody titer that other states. The evaluation of titers of antibodies in each animal, comparing the results of two by two strains showed statistical difference in most situations. It is concluded that there was a high frequency of occurrence of bovine reagents to BVDV, which varied according to the system of rasing and management of herds. Moreover, the use of different viral strains, independently of genotype or place of origin of isolate, increased the sensitivity of detection of seropositive animals in the VN. Cross-neutralization was observed among all strains studied. To increase the sensitivity of diagnosis it is important to select for VN the strains representative of the regions to be studied

Serological response of guinea pigs to oily and aqueous inactivated vaccines containing a Brazilian isolate of the Bovine Viral Diarrhea Virus (BVDV)

Bovine Viral Diarrhea Virus (BVDV) is widespread in cattle in Brazil and research shows its large antigenic variability. Available vaccines are produced with virus strains isolated in other countries and may not be effective. In this study, inactivated vaccines containing the Brazilian BVDV-Ib IBSP11 isolate were developed and tested on 6 groups of 10 guinea pigs (Cavia porcellus). Animals in groups A and C received an aqueous vaccine (aluminum hydroxide); B and D groups received an oily vaccine (Montanide ISA50); Group E positive-control animals were given an imported commercial vaccine with BVDV-la Singer; Group F animals were sham vaccinated (negative control). Groups A, B and E received two doses, and Groups C and D, three, every 21 days. Twelve blood samples were taken, at 21-day intervals over 231 days, and evaluated for antibody titer through virus-neutralization (VN), using a homologous strain (IBSP11), and a heterologous strain (BVDV-la NADL). Most animals, 42 days following the first dose, seroconverted to both strains and, after the second dose, there was a significant increase of titers in all groups. The oily formulation induced greater response after the third administration. This increase was not observed with the aqueous vaccines, regardless of the virus used in the VN. Antibody decline was more rapid in animals that received aqueous vaccines. The results showed the importance of studying the influence of endemic strains of commercial vaccines, to improve the efficacy of BVD vaccination. Use of the endemic strain in vaccine formulation presented promising results, as well as the use of guinea pigs as a laboratory model. (C) 2011 Elsevier Ltd. All rights reserved.Vallee LaboratoryVallee Laborator

Detection of antibodies against pestivirus in sheep with history of reproductive disorder in the State of São Paulo

ABSTRACT. Gaeta N.C., Rizzo H., Meira Jr E.B.S., Pituco E.M., Okuda L.H., Ribeiro C.P. & Gregory L. [Detection of antibodies against pestivirus in sheep with history of reproductive disorder in the State of São Paulo.] Detecção de anticorpos anti-pestivírus em ovinos com histórico de problema reprodutivo no Estado de São Paulo. Revista Brasileira de Medicina Veterinária, 38(2):153-156, 2016. Departamento de Clínica Médica. Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, Av. Prof. Orlando Marques de Paiva, 87, Cidade Universitária, São Paulo, SP 05508-270, Brasil. E-mail: [email protected] Pestivirus are responsible for reproductive disorders in sheep and, although they are widely studied in other countries, Brazil lacks information on the prevalence of virus in sheep flocks. To investigate the occurrence of pestiviruses in the State of São Paulo, 268 samples of serum sheep with a history of reproductive problems from 28 properties were collected. Using virusneutralization as the diagnostic technique, it was found two (1%) positive animals, with antibody titer of 20, with both females showing a history of reproductive problems, one with neonatal death and another, showing uterine secretion. Two properties studied showed reactive animals (7%). In five of these (18%), bovine co-creation was observed. There were no associations between any reagent animals and the risk factors studied. This work is one of the pioneers in the study of the prevalence of anti-pestivirus antibodies in Brazilian sheep flocks. The low frequency and low viral titer observed suggest that pestivirus are not an important agent related to the presence of reproductive disorders in sheep herds