Associations between health and productivity in cow-calf beef herds and persistent infection with bovine viral diarrhea virus, antibodies against bovine viral diarrhea virus, or antibodies against infectious bovine rhinotracheitis virus in calves

OBJECTIVE: To measure associations between health and productivity in cow-calf beef herds and persistent infection with bovine viral diarrhea virus (BVDV), antibodies against BVDV, or antibodies against infectious bovine rhinotracheitis (IBR) virus in calves. ANIMALS: 1,782 calves from 61 beef herds. PROCEDURES: Calf serum samples were analyzed at weaning for antibodies against type 1 and type 2 BVDV and IBR virus. Skin biopsy specimens from 5,704 weaned calves were tested immunohistochemically to identify persistently infected (PI) calves. Herd production records and individual calf treatment and weaning weight records were collected. RESULTS: There was no association between the proportion of calves with antibodies against BVDV or IBR virus and herd prevalence of abortion, stillbirth, calf death, or nonpregnancy. Calf death risk was higher in herds in which a PI calf was detected, and PI calves were more likely to be treated and typically weighed substantially less than herdmates at weaning. Calves with high antibody titers suggesting exposure to BVDV typically weighed less than calves that had no evidence of exposure. CONCLUSIONS AND CLINICAL RELEVANCE: BVDV infection, as indicated by the presence of PI calves and serologic evidence of infection in weaned calves, appeared to have the most substantial effect on productivity because of higher calf death risk and treatment risk and lower calf weaning weight.     

青海省牛传染性鼻气管炎及病毒性腹泻黏膜病血清学调查

从青海省互助、玛多、海晏、玉树、贵德、德令哈、共和等14个地区采集牛血清样品420份,应用酶联免疫吸附试验（ELISA）调查了青海省牛传染性鼻气管炎和病毒性腹泻黏膜病的感染情况。结果在被检牛血清420份样品中,共检出阳性血清样品228份,平均阳性率为50.67%（228/420）;在被检牦牛血清180份样品中,共检出阳性血清样品1份,平均阳性率0.56%（1/180）。     

Effect of maternal antibody upon vaccination with infectious bovine rhinotracheitis and bovine virus diarrhea vaccines.

This report presents the normal rate of decay of maternal antibody and the influence of maternal antibody on responses to a single vaccination with modified-live bovine virus diarrhea and infectious bovine rhinotracheitis virus vaccines at 196 days of age and on response to vaccinations with the same vaccines given twice at 84 and 196 days of age. Passive immunity decreased to near zero over the first six months of life for both bovine virus diarrhea and infectious bovine rhinotracheitis controls. All calves seroconverted to bovine virus diarrhea vaccine at 84 days of age, even though high levels (greater than 1:32) of maternal antibodies were present. These calves did not seroconvert to infectious bovine rhinotracheitis vaccine at 84 days of age when high levels (less than 1:16) of maternal antibodies were present. Calves responded well to bovine virus diarrhea and infectious bovine rhinotracheitis vaccines given only once at 196 days of age after passive immunity disappeared. Calves which were revaccinated with infectious bovine rhinotracheitis seroconverted showing a more rapid response than the single vaccinates. Those revaccinated with bovine virus diarrhea showed an immediate response of small magnitude.     

江苏规模化奶牛场BVD与IBR流行病学调查

为了解江苏地区规模化奶牛场牛传染性鼻气管炎(IBR)及牛病毒性腹泻病(BVD)流行与分布情况,采用商品化酶联免疫吸附试验(ELISA)试剂盒对来自江苏省7个市和不同地区的13个大型规模化奶牛养殖场共540份血清中IBRV抗体进行检测,采用商品化ELISA试剂盒对来自江苏省5个市和不同地区的11个大型规模化奶牛养殖场共460份血清中BVDV抗体进行检测,同时从中随机采集100份血清样本,采用巢式逆转录聚合酶链式反应(nRTPCR)进行BVDV抗原检测与基因分型。结果表明:不同牛场的BHV-Ⅰ抗体阳性率为0%~82.1%%,平均阳性率为21.1%(114/540);不同牛场的BVDV抗体阳性率为0%~98%,平均阳性率为51.5%(237/460);不同牛场的BVDV抗原阳性率为0%~100%,平均阳性率为55%(55/100);对相应样本的BVDV抗原与抗体检测结果进行比较表明,抗原~+/抗体~+牛占40%(40/100),抗原~+/抗体~-牛占15%(15/100),抗原~-/抗体~-牛占35%(35/100),抗原~-/抗体~+牛占10%(10/100);基因分型结果显示,BVDV-Ⅰ型占11%(6/55),BVDV-Ⅱ型为78%(43/55),Ⅰ型与Ⅱ型混合感染占11%(6/55),未发现BVDV-Ⅲ型。研究表明,BVDV和BHV-Ⅰ在江苏省主要规模奶牛场普遍流行,但不同地区、不同牛场的阳性率存在明显差异,大部分牛场均能检测出抗原~+/抗体~-的持续感染牛,BVDV含基因Ⅰ、Ⅱ型,但主要以Ⅱ型感染为主。     

Association of bovine viral diarrhea virus with multiple viral infections in bovine respiratory disease outbreaks

We investigated eleven outbreaks of naturally occurring bovine respiratory diseases in calves and adult animals in the St-Hyacinthe area of Quebec. Specific antibodies to bovine herpesvirus-1, bovine viral diarrhea virus, respiratory syncytial virus, parainfluenza type 3 virus, reovirus type 3, and serotypes 1 to 7 of bovine adenovirus were found in paired sera from diseased animals. Several bovine viruses with respiratory tropism were involved concomitantly in herds during an outbreak of bovine respiratory disease. In addition, concomitant fourfold rises of antibody titers were frequently observed to two or more viral agents in seroconverted calves (61%) or adult animals (38%). Bovine viral diarrhea virus was found to be the most frequent viral agent associated with multiple viral infection in calves only (92%).     

Nitrogen metabolism of calves inoculated with bovine adenovirus-3 or with infectious bovine rhinotracheitis virus

Beef calves were inoculated with bovine adenovirus-3 or infectious bovine rhinotracheitis virus. After inoculation, plasma fibrinogen increased, serum phosphorus decreased, and nitrogen and phosphorus digestibility decreased compared with preinoculation values. Urinary N excretion increased when calves developed rectal temperatures greater than 39.7 C. Results indicated that clinical infection of calves with infectious bovine rhinotracheitis virus increases urinary N excretion and reduces N and phosphorus balance, and that clinical and subclinical infections with either virus reduce dietary N digestibility.     

Laboratory diagnosis of bovine viral diarrhea virus infections.

The past 20 years have witnessed dramatic improvements in laboratory methods for diagnosing bovine viral diarrhea virus(BVDV) infections. However, improvements in diagnostic technology have not necessarily led to improved diagnosis of BVDV at the individual animal or herd level. This article reviews BVDV laboratory diagnostic methods in the context of their rational application for improved detection of BVDV in the field.     

Enhancement of infectious bovine rhinotracheitis virus replication with corticosterone

Infectious bovine rhinotrachetis virus (IBRV) progeny was increased ten to 12 fold in bovine turbinate (BT) cells treated with 10^?3 M corticosterone acetate (CCA) as demonstrated by plaque assay. Autoradiographic studies demonstrated an increased binding of ³H-corticosterone (³H-CS) in IBRV infected cells and the fractionation of labelled cells revealed 78–80% of the total hormone associated with the cytoplasmic components. Incorporation of ³H-uridine and ³H-valine precursors into cells treated with the hormone demonstrated up to 16-fold increase in RNA and protein synthesis which was inhibited by the addition of actinomycin D. The data suggest that increased rate of macromolecular synthesis in IBRV infected cells treated with the corticosteroid may result in the enhancement of virus production.     

Enhancement of infectious bovine keratoconjunctivitis by modified-live infectious bovine rhinotracheitis virus vaccine

The effects of a modified-live infectious bovine rhinotracheitis virus vaccine (administered ocularly or intranasally) on experimentally induced infectious bovine keratoconjunctivitis were evaluated. The modified-live infectious bovine rhinotracheitis virus vaccine was administered to 13 male Holstein calves (intranasally in 4 and ocularly in 9; day 0). Five calves were not vaccinated and served as controls. Calves were examined daily and, starting on day 4, Moraxella bovis was administered ocularly to all 18 calves once daily for 4 days. The eyes of all calves were assigned a clinical score, and the ocular secretions were evaluated for presence of infectious bovine rhinotracheitis virus and M bovis daily until day 19. The severity of the ocular lesions was estimated by scoring the lesions clinically and by determining the protein concentration, myeloperoxidase activity, and WBC count in the tears. By day 5, conjunctivitis, chemosis, and epiphora were observed in all of the calves vaccinated ocularly. The calves vaccinated intranasally developed conjunctival plaques, but did not develop chemosis or photophobia. All of the calves developed keratitis after inoculation with M bovis. The median lesion scores were greater in both groups of vaccinated calves than in the controls. Corneal perforations developed exclusively in the vaccinated calves. The frequency of M bovis isolation from ocular secretions was significantly (P less than 0.05) greater in the vaccinated calves than in the controls. The tears from the intranasally vaccinated calves contained the highest myeloperoxidase activity and WBC count. The mean protein concentration in the tears of vaccinated calves was not significantly different from that in tears of controls.(ABSTRACT TRUNCATED AT 250 WORDS)     

Seroconversion to bovine viral diarrhoea virus and infectious bovine rhinotracheitis virus in dairy herds of Michoacan, Mexico

Bovine viral diarrhoea virus (BVDV) and infectious bovine rhinotracheitis virus (IBRV) are important viral diseases around the world. The objective of this study was to estimate the incidence of seroconversion to BVDV and IBRV and to identify associated risk factors in dairy herds of Michoacan, Mexico. The longitudinal study included 62 herds and ran from December 2001 to November 2002. The total number of animals enrolled and completing the study were 392 and 342 animals for BVDV and 925 and 899 animals for IBRV. Animals were tested monthly for 12 months, for the presence of antibodies. Risk factors were: herd size (2–9, 10–25 and 26–55 animals), herd serostatus (seropositive or seronegative, only for IBRV), age group of the animal (6 to 12, 13 to 24, 25 to 48 and > 48 months) and animal origin (born in farm, purchased). The cumulative incidences for BVDV and IBRV were 16.4% and 3.4%, respectively; whereas, the incidence density rates for BVDV and IBRV were 15.9 and 2.9 per 1000 animal-months at risk, respectively. Seroconversion curves were statistically different for age group for BVDV and IBRV and for herd status for IBR. The relatively high incidence of seroconversion for BVDV suggests that a successful control programme should be oriented towards the identification and elimination of the PI animals and towards avoiding the introduction of PI cattle to the farm. The scenario of IBRV is favourable to implement a programme directed to reduce the number of new seropositive herds.     

Reactivation of infectious bovine rhinotracheitis virus by transport

Transport was studied as a cause of reactivation of infectious bovine rhinotracheitis virus (Bovine herpesvirus-1; BHV-1) in heifers vaccinated 2-6 months before transport, using a double dose of the thermosensitive (ts) vaccine strain (Tracherine). Eight out of 19 animals showed ts strain re-excretion over a period of 1-3 days, beginning, in 5 out of the 8 heifers, the day after transport. In 14 other heifers, only sera were examined by sero-neutralisation: only 1 out of these 14 animals showed a rise in BHV-1 neutralising antibodies. Transport can therefore be considered as a stimulus of BHV-1 reactivation.     

The pathology of concurrent bovine viral diarrhoea and infectious bovine rhinotracheitis virus infection in newborn calves

Concurrent bovine viral diarrhoea (BVD) and systemic infectious bovine rhinotracheitis (IBR) are reported from two neonatal (11 and 15 days old) calves. The diseases occurred sporadically in a large-scale herd which may have been due to the calves' heterogeneous immunobiological status. Gross pathological and histopathological examinations revealed focal interstitial pneumonia with acidophilic intranuclear inclusions in the alveolar epithelial cells and necrotic foci in the liver with a few intranuclear inclusions in the hepatocytes. There were subserous haemorrhages in the forestomachs and intestine, necrotic changes in the rumen, enteritis, lymphocytic necrosis in the Peyer's patches, and fibrinoid necrosis in the wall of some of the neighbouring blood vessels. BVD virus was demonstrated by immunofluorescence (IF), whereas IBR virus by electron microscopy, immunofluorescence and virus isolation.     

Isolation of infectious bovine rhinotracheitis virus in Tanzania

Summary Infectious bovine rhinotracheitis (IBR) virus was identified for the first time in Tanzania. The virus isolations were made from cattle affected with respiratory diseases. Concurrent infection with foot-and-mouth disease was observed and enhanced the severity of the illness.

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Sumario El virus de la rinotraqueitis infecciosa de los bovinos (I.B.R.) ha sido identificado por primera vez en Tanzania. Los aislamientos de virus fueron hechos de bovinos afectados con enfermedades respiratorias. Se observó infección concurrente con fiebre aftosa y este hecho exacerbaba la severidad de la enfermedad.

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Résumé Ce virus a été isolé pour la première fois en Tanzanie, à partir de bétail atteint d'affections respiratoires. Cette maladie a sévi concurremment avec la fièvre aphteuse, ce qui explique sa sévérité.