Interface between Maternal Antibodies and Natural Challenge for Bovine Viral Diarrhea Virus (BVDV) in Holstein Heifers

Background: Newborn calves are agammaglobulinemic, immunosuppressed and immunologically immature at birth. The passive immune transfer is fundamental to protect calves against pathogens. The decay of maternal antibodies precedes the immune maturation at puberty enhancing the susceptibility of calves to infections caused by BVDV. Then, the objective of this research was to evaluate the interface between passive and active immunity for Bovine Viral Diarrhea Virus (BVDV) in Holstein dairy heifers in the first 13 months of age to detect susceptibility periods and establish prophylactic measures on prevention of Bovine Viral Diarrhea.Materials, Methods & Results: Sera were analyzed from 585 heifers by serum neutralization (SN) and enzyme linked immunosorbent assay (ELISA) for the p80 protein of BVDV. Heifers were categorized according to their age by the month of life. Heifers were seropositive (100%) from 1st to 13th. Median of neutralizing antibodies (Ab) titers obtained from 1st up to 13th month were 316.2; 125.9; 63.1; 50.1; 50.1; 39.8; 63.1; 63.1; 39.8; 79.4, 100.0; 74.4; and 79.4, respectively. The neutralizing Ab titers obtained in 1st month were different of the values observed from 2nd until 13th (P < 0.001), furthermore the Ab titers from 2nd month was statistical different of 4th (P = 0.01) and 6th (P = 0.05). The frequencies (%) of positive heifers for p80 from 1st up to 13th were 24.7; 18.2; 10.4; 11.8; 73.3; 73.8; 72.4; 58.1; 45.9; 48.4; 46.2; 43.8 and 61.5, respectively. The correlation observed for neutralizing Ab titers and age was negative and weak (ρ= -0.299; P < 0.001). On the other hand, the correlation between positive heifers for p80 and age was positive and moderate (ρ= 0.319; P < 0.001).Discussion: The newborn calves had higher titers of neutralizing antibodies than other age groups and some calves were seropositive for the p80 protein. This profile points to the transfer of maternal antibodies produced by vaccination and/or natural exposure to BVDV. The exposure of the cows to the inactivated and live virus stimulates the production of neutralizing antibodies to the structural proteins of the virus, particularly the glycoprotein E2, detected by the serum neutralization test. The titers of serum neutralizing antibodies and the frequencies of seropositive for p80 protein decreased gradually from the first to the 4-6th month of life due to the metabolization of maternal immunoglobulins acquired by ingestion of colostrum. Frequencies of seropositive animals for protein p80 increased from the fifth month of life, which is the same moment that was observed declined of neutralizing maternal antibody titers. The phase of higher frequency of p80 positive animals coincides with greater rates of Babesiosis and Anaplasmosis. This history could justify the importance of the BVDV immunodepression as a risk factor for concomitant diseases. In general, the neutralizing antibody titers increased after the peaks of positive reactions to the p80 protein, but this moment coincides with the primo-vaccination in calves. Therefore, it is not possible to state the origin of these antibodies. Correlations between ages and serologic tests are consistent with previous data reporting the decrease in antibody titers and increase of seropositive animals for p80 protein, from the first month of life to puberty. In conclusion, maternal neutralizing Ab titers had gradual decreased whereas the frequency of positive heifers for p80 had increased values. The inversion observed between the maternal antibody titers and the increase in antibody for p80 indicates the moment of greatest risk for natural infections caused by BVDV

Pesquisa de anticorpos contra o vírus da Estomatite Vesicular em bovinos de corte criados na região de Araçatuba, Estado de São Paulo, Brasil em 2000

In 2000 a total of 1099 serum samples were obtained of adult beef cattle, from 6 herds located at Auriflama, Gastão Vidigal,, Magda, Santo Antônio do Aracanguá, Sebastianópolis do Sul e Turiúba, counties from the region of Araçatuba. Sera were tested for neutralizing antibodies to vesicular stomatitis virus by microtiter neutralization assay, using the virus strain Indiana 1 Costa Rica/72 with 10(6,0) DICT50/50mL. The indicator cells were African green monkey kidney (VERO-CCL 81), purchased from American Type Cell Colection (ATCC). The neutralization titers of each serum were the reciprocal of the highest dilution expressed at log10 that protected 100.00% of the cell monolayer. Sera with values above 1,6 log10 (1/40) were considered positive for Vesicular Stomatitis virus. Twenty-eight (2.50%) out of 1.099 samples were positive for Vesicular Stomatitis virus Indiana 1, with antibodies titers ranging from 1.9 to 2.8. Except in Turiuba, in the others 5 herds there were positive animals. The presente survey showed the presence the Vesicular Stomatitis virus in the herds stimulating the humoral response. More studies are necessary to verify the site of persistence of the virus.No ano de 2000 foram pesquisadas 1099 amostras de soro de bovinos de corte, adultos, pertencentes à seis rebanhos situados nos municípios de Auriflama, Gastão Vidigal,, Magda, Santo Antônio do Aracanguá, Sebastianópolis do Sul e Turiúba, região de Araçatuba. A técnica empregada para a dosagem de anticorpos para o vírus da Estomatite Vesicular foi a soroneutralização em microplacas, utilizando a cepa Indiana 1 Costa Rica/72 com título de 10(6,0) DICT50/50mL. As células utilizadas foram as da linhagem de Rim de Macaco Verde Africano (VERO-CCL 81), provenientes do American Type Cell Colection (ATCC). O título de anticorpos de cada amostra de soro, foi calculado como a recíproca da maior diluição do soro expresso em log10, que protegeu 100,00% da monocamada celular. Foram consideradas positivas as amostras com título superior a 1,6 log10 (1/40). Das 1099 amostras de soro analisadas, 28 (2,50%) foram positivas ao vírus da Estomatite Vesicular tipo Indiana 1, com títulos de anticorpos variando de 1,9 à 2,8. Com exceção do rebanho situado no município de Turiúba, nos outros cinco foram encontrados animais reagentes ao vírus. Esta avaliação mostrou que houve circulação do vírus da Estomatite Vesicular nestes rebanhos provocando resposta humoral. Sendo assim é necessário a realização de estudos para se determinar o sítio de permanência do vírus

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

DETECÇÃO DE ANTICORPOS CONTRA O VÍRUS DA LÍNGUA AZUL EM OVINOS NA REGIÃO DE ARAÇATUBA – SÃO PAULO, BRASIL

A língua azul é uma doença viral, cujo agente etiológico pertence à família Reoviridae, gênero Orbivirus, transmitida por um vetor (artrópode) hematófago, do gênero Culicoides. Os animais acometidos são ruminantes domésticos e selvagens, porém os pequenos ruminantes são os mais afetados. O estudo teve como objetivo detectar a presença de anticorpos para língua azul em ovinos da região de Araçatuba, por possuir um rebanho expressivo e condições climáticas favoráveis à multiplicação de insetos. Foram analisadas 1.002 amostras de soros ovinos, provenientes de 31 cabanhas, pelas provas de imunodifusão dupla em gel de ágar (AGID) e ELISA (Enzyme Linked immunosorbent Assay) de competição da fase sólida (ELISA CFS), provenientes do Centro Panamericano de Febre Aftosa. Desses soros, 651 (65%) foram reagentes ao vírus da língua azul, pela técnica de AGID, e 742 (74,1%) ao teste de ELISA–CFS. Esses resultados sugerem que o vírus da língua azul encontra-se disseminado nessas regiões, ocasionando infecções inaparentes.  PALAVRAS-CHAVES: AGID, ELISA, inquérito soroepidemiológico, vírus da língua azul

Bovine Respiratory Disease (BRD) Complex as a Signal for Bovine Viral Diarrhea Virus (BVDV) Presence in the Herd

Background: Infections are caused by Bovine Viral Diarrhea Virus and still continue to be a worldwide plague in cattle industry. It is responsible for sudden death syndromes in adult cattle with high mortality rates, abortions, acute gastrointestinal and respiratory diseases. The BVDV infection occurs in early pregnancy (40-142 days), in immunosuppressed females or cows results in 100% of persistently infected (PI) calves that are seronegative and asymptomatic at birth. Evidences suggests that BVDV contributes to BRD complex potentiating secondary infections caused by Mannheimia haemolytica e Pasteurella multocida due to its immunosuppressive action. However, the farmers have often associated the respiratory syndrome with other infectious agents. This paper reports the attendance of dairy calves manifesting clinical signs of bronchopneumonia, which led to the screening of the persistently infected animals to control of the BVDV infection in the herd.Materials, Methods & Results: During the technical assistance, ten calves manifesting bronchopneumonia were selected to trans-tracheal lavage (TL) in order to identify possible infectious agents. Reverse transcription polymerase chain reaction (RT-PCR) detected the presence of BVDV in two heifers. Pasteurella multocida was the unique bacterial agent isolated from TL (5/10, 50%). These data motivated the technical team and producers to investigate the PI screening by direct enzyme-linked immunosorbent assay from biopsies of the ear edge. The screening of PI’s detected 29 positive within of 2,342 animals tested (1.23%). The re-test of positive was performed only in 24 animals due to the cull of five bovine with severe bronchopneumonia and diarrhea, confirming 18 persistently infected calves (18/24; 75%). Finally, in all PI’s live dams were tested. It was observed four positive adult animals. One grand dam was live and tested, but it had negative result for direct enzyme-linked immunosorbent test. The rate of PI’s considering the whole herd was 0.81% (22/3,700 animals).Discussion: The involvement of BVDV in the etiology of bronchopneumonia was confirmed by detection of the virus in trans-tracheal lavages in two calves by RT-PCR. The susceptibility for Pasteurella multocida infection could be promoted by BVDV prime-infection, considering that immunossupressive nature of BVDV is a critical factor in the interaction with others viruses and bacteria. At this time, we are aware about any report about the detection of BVDV in trans-tracheal lavages. These findings culminated with the screening of PI animals in the herd, detecting rates of 0.81%. The intensive vaccination and colostrum management of this farm could protected the herd against BVDV, however others facts facilitated the introduction of the virus in the herd. This research was conduced in a high-production dairy farm with around 3,700 animals raised in an open herd, in which some of cows with high genetic potential were transferred for embryo collection in the state of Paraná, Brazil; resulting in the addition of the calves to the herd by others routes. Moreover, the farm used for many years vaccine containing only BVDV-1, which may have favored the entry and spread of BVDV-2 or BVDV-3 in the herd. This research showed the presence of BVDV in trans-tracheal lavage of heifers with bronchopneumonia by RT-PCR. This fact points to the need of BRD control programs that include detection of PI animals

Infecção natural pelo vírus da diarreia viral bovina (BVDV) em bovinos de corte no Estado do Pará

Background: Bovine viral diarrhea virus (BVDV) is a pathogen that causes great economic losses in dairy and beef herds.The main disturbances caused by this virus are related to abortion, fetal malformation and mummification, and the birth ofweak calves. In addition, this disease may result in persistently infected animals, as well as individual immune tolerance tothe virus. However, the symptoms are nonspecific and variable, and dependent on the age of affected animal. The objectiveof the present study was to report three cases with clinical signs of BVDV infection, with subsequent confirmation of thediagnosis by reverse transcription - polymerase chain reaction technique (RT-PCR).Cases: In a beef production farm located at the state of Para, Brazil, three animals presented severe diarrhea; the feces wereliquefied and greenish-yellow in color; crusted lesions were visible and scattered over various parts of the animals’ bodies,including the muzzle, nostrils, periauricular region, and hooves; the tongue mucosa was undergoing an intense desquamationprocess. One of the affected animals, a 6-month-old calf, was euthanized following the recommendations of the “Brazilianguide to good practices for animal euthanasia” of the Ethics, Bioethics and Animal Welfare Committee / Federal Council ofVeterinary Medicine. After euthanasia, this calf was necropsied and some of its organs, including the tongue and skin, weresent to the Biological Institute of Sao Paulo State for histopathology examination (HE) and identification and isolation of thevirus. Positive samples for the presence of BVDV were diagnosed by RT-PCR, confirming the suspicion and explaining thesigns observed in that animal and reported in other dead animals of the farm. Because RT-PCR was performed in ulcerativelesions present in the tongue, negative reactions were detected for bovine herpesvirus (BoHV) and positive reactions forBVDV. The cutaneous tissue was marked with lymphocytic infiltration, observed in both epidermis and dermis, which refersto crusted lesions distributed in several regions of the animal’s body. In the lungs, we observed rare areas of emphysema andmarked lymphocytic interstitial pneumonia with hemorrhagic spots, correlated with symptoms of respiratory disease. Also,marked renal damage and spleen lesions were identified, indicating glomerulonephritis and lymphocytic splenitis.Discussion: This study evidenced the occurrence of BVDV in two calves and one adult animal, which is in agreementwith the described higher incidence of symptomatic infection in young animals. Clinical signs of severe greenish-yellowdiarrhea and crusted lesions distributed throughout several regions of the animals’ bodies, including the muzzle, nostrils,periauricular region, and hooves were described, with intense tongue epithelium desquamation, which is a particular andcharacteristic symptom of Mucosal Disease - the classical form of the physiopathogeny caused by bovine viral diarrheavirus. The clinical findings of severe diarrhea are possibly related to the histopathological results, which showed hyaliniza-tion of the intestinal mucosa and rare mononuclear cells in the liver nodules. Pulmonary histopathological findings of rareareas of lymphocytic interstitial pneumonia, severe emphysema, and hemorrhagic foci refer to respiratory diseases. Basedon the clinical signs and laboratory findings, we conclude that the affected animals showed classic symptoms of bovineviral diarrhea. This diagnosis highlights the presence of the disease in cattle raised in the state of Para, Brazil

Índices reprodutivos e características de desempenho em bovinos de corte infectados pelo Herpevírus Bovino 1

Reproductive rates and performance traits in beef cattle females infected by Herpesvirus Bovine-1 (BoHV-1) were evaluated in a farm at São Paulo state, Brazil. Gir, Guzerá, Nelore and Caracu purebred animals were examinated to BoHV-1 (ELISA) at the beginning of the breeding season and the occurrence of reactors was 54.2% (386/712). BoHV-1 did not interfere in the pregnancy rates of both reagent - 80.3% (310/386) and non-reagent - 74.5% (243/326) females. It did not reduce the parturition rate of both reagent - 97.7% (300/307) and non-reagent - 93.8% (225/240) females. Total rate of stillbirths in BoHV-1 reagent females - 1.3% (4/300) did not differ from non-reagent females - 2.2% (5/225). BoHV-1 did not affect performance traits for reagent and non-reagent females, respectivelly, to daily weight gain during the breeding season (459.90 ± 2.82 g and 466.63 ± 2.87 g), body condition score at the beginning of the breeding season (6.89 ± 0.08 and 6.99 ± 0.08), body condition score at the end of the breeding season (7.73 ± 0.06 and 7.71 ± 0.06), weight at parturition (419.17 ± 3.34 kg and 425.97 ± 3.22 kg). It was concluded that non-vaccinated beef cattle females infected by BoHV-1 and bred under adequate extensive management, with body condition score over 5 and gain of weight during the breeding season presented good pregnancy, parturition and birth rates, no matter the breed, genetic group, age and seroconvertion.Avaliou-se índices reprodutivos e características de desempenho em fêmeas bovinas de corte, infectadas pelo Herpesvírus Bovino-1 (BoHV-1), em um rebanho no Estado de São Paulo, Brasil. Animais das raças Gir, Guzerá, Nelore e Caracu foram monitorados no início da estação de monta e a sororeatividade ao BoHV-1 pelo teste ELISA foi 54,2% (386/712). O BoHV-1 não interferiu no índice de prenhez de matrizes reagentes - 80,3% (310/386) e não reagentes - 74,5% (243/326) e nem reduziu a taxa de parição de matrizes reagentes - 97,7% (300/307) e não reagentes - 93,8% (225/240). O coeficiente de natimortalidade de matrizes reagentes ao BoHV-1 - 1,3% (4/300) não diferiu da encontrada para as não reagentes - 2,2% (5/225). O BoHV-1 não afetou a média de algumas características de desempenho de fêmeas reagentes e não reagentes, respectivamente, como ganho de peso médio diário durante a estação de monta (459,90 ± 2,82 g e 466,63 ± 2,87 g), condição corporal na entrada da estação de monta (6,89 ± 0,08 e 6,99 ± 0,08), condição corporal na saída da estação de monta (7,73 ± 0,06 e 7,71 ± 0,06) e peso à parição (419,17 ± 3,34 kg e 425,97 ± 3,22 kg). Concluiu-se que matrizes de corte infectadas pelo BoHV-1 e não vacinadas, criadas sob condições adequadas de manejo zootécnico extensivo e nutricional, como escore corporal acima de 5 e ganho de peso durante a estação de monta, apresentaram bons índices de prenhez, parição e natalidade, independente da raça, grupo genético, faixa etária e soroconversão

Bovine Leukosis Virus and Antibodies against Bovine Herpesvirus Type-1 and Bovine Viral Diarrhea Virus and in Buffaloes of the State of Pará, Brazil

Background: Viral diseases affecting reproduction cause economic losses in cattle, as reproductive failure interrupts the production cycle, thus reducing herd productivity. Buffaloes are susceptible to most of the diseases that affect cattle. Some of the viral diseases of reproductive importance are infectious bovine rhinotracheitis (IBR), bovine viral diarrhea (BVD), and bovine leukosis (BL). The objective of this study was to determine the seroprevalence of IBR virus (bovine herpes virus-1, BoHV-1), BVD virus (BVDV), and BL virus (BLV) in female buffaloes living in wetland areas or plains in the state of Pará, as well as the seroprevalence of BoHV-1, BVDV, and BLV in females of different age groups.Materials, Methods &amp; Results: It were used 225 crossbred buffaloes from 4 buffalo exclusive farms. The buffaloes reared on farms A (n = 50) and B (n = 89) were kept in wetland areas on Marajó Island (n = 139), Pará. On farms C (n = 30) and D (n = 56) buffaloes were kept in plains (n = 86) in a northeastern mesoregion of Para. Animals were categorized into age groups: I: 0-3 years (n = 34), II: 3-6 years (n = 58), III: 7-9 years (n = 55), and IV: over 9 years (n = 78). Blood samples were collected and sera were sent for processing at the Bovine Virus Laboratory, Biological Institute of São Paulo, Brazil. The presence of IBRV and BVDV was determined by neutralization and BLV antibodies by immunodiffusion in agar gel. Statistical analysis was performed using the Ȥ2 test at a significance level of 5%. Among the seroprevalences of IBRV, BVDV and BLV antibodies, the difference in prevalence for BVD [P &lt; 0.01] was observed between wetland areas and plains of Para, varying from 12.4% to 96.0% and 0.0% to 13.3%, respectively. While levels of IBRV remained high on farms A (79.6%), B (86.5%), C (83.3%) and D (89.1%) [P = 0.60] and BLV was negative in all the animals. BVDV was similar for all the age groups [P = 0.60], while IBRV was more prevalent in animals over 6 years of age with group I: (76.5%), II (74.5%), III (92.3%) and IV (91.3%) [P = 0.01]. It was not possible verify the influence of age in prevalence for BL.Discussion: The prevalence obtained for the BoHV-1 on farms was high, with little variation between 79.6% and 89.1%. The high prevalence of BoHV-1 suggests the free circulation of the virus in the state of Para. Notably, the animals in this study had not been vaccinated, so the determined viral antibody titers were independent of vaccination. BVDV results showed high variation between 0.0% and 96.0%. The highest prevalence in wetland areas may be related to the breeding environment, because of a possible horizontal contamination. The lack of BLV antibodies prevalence can be attributed to the fact that all the evaluated animals were kept in an extensive breeding system where they had little direct contact. The prevalence of IBR was higher in the older animals. Variation in prevalence with age was not observed for BVD. It was concluded that the prevalence for IBR and BVD were high indicating that the etiological agents are circulating in Para, with IBR having a higher prevalence in older animals. Breeding buffalo in wetland areas may favor horizontal transmission of BVDV because facilitate contact of healthy animals with water contaminated by virus carriers animal secretion and the absence of seropositive animals at the BLV does not necessarily indicate that buffaloes are resistant to the virus

Complete genome sequences of two bovine alphaherpesvirus 5 subtype C strains from southeast Brazil

Bovine alphaherpesvirus 5 causes meningoencephalitis in cattle, belongs to the Herpesviridae family, and can be divided into subtypes a, b, and c. Limited information is available about subtype c. Here, we report the complete genome sequences of two strains, P160/96, and ISO97/45, isolated from cattle in southeast Brazil