IBR Virus Research Articles

Development of differentiation method for bovine herpesvirus serotypes (BHV-1, BHV-4, BHV-5) using polymerase chain reaction

Infectious pneumoenteritis of cattle is etiologically caused by viruses of different families and species. Bovine herpesvirus type 1 — infectious rhinotracheitis virus — is the main and the most dangerous pathogen transmitted by cattle semen. At the same time, recently, according to European scientists’ data, in addition to this pathogen, other herpesviruses have been circulating in cattle groups, in particular, bovine herpesvirused of types 4 and 5. Studies have been conducted using molecular-genetic and bioinformatic methods. Based on the analysis of the genomes of bovine herpesvirus of types 1 (IBR virus), 4 and 5 we developed primers BoHV-1 F/R, which flanks the DNA fragment of the IBR virus with the length of 204 bp, BoHV-4 F/R, which flanks the DNA fragment of bovine herpesvirus type 4 with the length of 615 bp, and BoHV-5 F/R for bovine herpesvirus type 5 DNA amplification with the formation of specific fragments 158 bp in length. The tests demonstrated that primers specific for bovine herpesvirus of types 1, 4 and 5 can be used in multiplex amplification format and hybridized only with specific DNA matrices of bovine herpesviruses. A standard operating procedure ‘Indication of DNA of infectious bovine rhinotracheitis virus and bovine herpesviruses of types 4 and 5 by polymerase chain reaction’ has been developed

Effects of dietary energy level and intake of corn by-product-based diets on newly received growing cattle: antibody production, acute phase protein response, stress, and immunocompetency of healthy and morbid animals.

Effects of dietary energy level and intake of corn by-product-based diets on antibody production, acute phase protein response, stress, and immunocompetency of healthy and morbid newly received growing cattle were evaluated. Four dietary treatments were formulated to supply 0.99, 1.10, 1.21, and 1.32 Mcal NEg/ kg DM and were offered at 100%, 95%, 90%, and 85% of ad libitum based on 0.99/100 treatment intake, respectively. Thirty-two pens were utilized with approximately 12 animals/pen. Four animals from each pen (32/dietary treatment) were randomly selected and used to serve as a subset to monitor immune function and acute phase proteins following a split-plot design. In addition, two animals were randomly and independently selected from each pen (16/dietary treatment) and used to measure fecal cortisol metabolite. Additionally, animals removed from the pen one (M1), two (M2), or three (M3) times and classified as morbid were bled in conjunction with a healthy control (H) removed at the same time and the serum analyzed for the same parameters. A quadratic response to time (P < 0.01) was detected for haptoglobin concentrations and for antibody titers for bovine viral diarrhea type 1 (BVD-I) and infectious bovine rhinotracheitis (IBR; P < 0.01). Haptoglobin was lowest on arrival, highest on day 14, and similar to baseline levels by day 27. Titer levels for BVD-I and IBR were lowest on arrival, higher on day 14, and significantly higher on day 27. Titers for bovine viral diarrhea type 2 (BVD-II) responded linearly (P < 0.05) with lower levels on arrival and highest levels on day 27. Haptoglobin was elevated in morbid animals compared to healthy pen mates (P < 0.05). Titer levels for BVD-I and IBR were also higher in healthy animals compared to animals pulled for morbidity (P < 0.01). Fecal cortisol was higher on arrival than on day 14 (P < 0.05). Dietary treatment had no effect on any of the parameters investigated. In summary, high-energy receiving diets based on fermentable fiber from by-products can be fed to newly received growing cattle without negative effects on antibody production toward vaccines, inflammation, or overall stress. In addition, haptoglobin concentrations and titer levels for BVD-I and IBR viruses are higher in healthy animals compared to sick animals.

Seroprevalence of bovine herpesvirus 1 related alphaherpesvirus infections in free-living and captive cervids in Poland

To determine the occurrence of bovine herpesvirus 1 (BoHV-1) related alphaherpesvirus infections in cervids, 1194 serum samples of wild ruminants originating from 59 forest districts of Poland were tested with IBR gB ELISA and virus neutralization test (VNT) against BoHV-1 and cervid herpesvirus 1 (CvHV-1). The seroprevalence differed significantly between free-living and captive cervids (P<0.001) with a total of 89 out of 498 (17.9%) and 268 out of 696 (38.5%) seropositive animals in each type of population. In free-ranging cervids, the highest seroprevalence was found among red deer (25.6%) and in fallow deer (23.1%), while it was the lowest in roe deer (1.7%). The seroprevalence varied at the district level between 0 and 100% with the mean value of 17.4% (95% CI:10.1–24.0). Additionally, seroprevalence was associated with afforestation (χ2=7.5; P=0.006) and to some degree with the mean of cattle density in province (χ2=7.0; P=0.08). The mean antibody titre against CvHV-1 in VNT (161.8; 95%CI: 146.0–177.6) has been significantly higher (P<0.0001) than the mean titre of BoHV-1 antibodies (10.1; 95%CI: 8.9–11.4). The results showed that BoHV-1 related alphaherpesvirus infections are present in population of free-ranging and farmed cervids in Poland. Based on the VNT results and considering the low susceptibility of red deer to BoHV-1, it seems that the dominant alphaherpesvirus circulating in wild ruminants is most likely CvHV-1 and therefore it is rather unlikely that deer in Poland could play any role as a reservoir of BoHV-1 for cattle.

Determination of Cultural Conditions of Infectious Bovine Rhinotracheitis Virus Strain “BM”

Abstract The purpose of our research was to determine cultural properties and cultural conditions of the infectious bovine rhinotracheitis virus of “BM” strain. Sensitivity of different cell lines to IBR virus was studied. The most effective system for cultivation of IBR virus turned MDBK cell line. Optimum multiplicity of infection was 0.01 TCD 50 /cell in which infectious virus replication activity is the highest. The research work proved that influence of maintenance medium and the presence of serum had no effect on the virus productivity. It was also proved that the method of infection significantly effects on intensity of accumulation of the virus.

Studies on Antimicrobial and Immunomodulatory Effects of Hot Aqueous Extract of Acacia nilotica L. Leaves against Common Veterinary Pathogens.

Acacia nilotica is a plant species that is almost ubiquitously found in different parts of the world. Various preparations of it have been advocated in folk medicine for the treatment of tuberculosis, leprosy, smallpox, dysentery, cough, ophthalmia, toothache, skin cancer as astringent, antispasmodic, and aphrodisiac since immemorial times. The present study investigates the antibacterial, antifungal, antiviral, and immunomodulatory potential of hot aqueous extract (HAE) of Acacia nilotica leaves. On dry matter basis, the filtered HAE had a good extraction ratio (33.46%) and was found to have carbohydrates, glycosides, phytosterols, phenolic compounds, saponins, and flavonoids as major constituents. HAE produced dose dependent zone of inhibition against Klebsiella pneumoniae, Pseudomonas aeruginosa, E. coli, Bacillus cereus, Staphylococcus aureus, and Streptococcus uberis and fungal pathogens Aspergillus niger and Aspergillus fumigates; however, no antiviral activity was recorded against IBR virus. HAE of A. nilotica revealed both proliferative and inhibitory effects on the rat splenocytes and IL-10 release depending on the dose. Detailed studies involving wide spectrum of bacterial, fungal, and viral species are required to prove or know the exact status of each constituents of the plant extract.

245 : Antiviral and cytokine modulating potential of Chlorophytum borivilianum hot aqueous extract

Objective of this study was to investigate the antiviral properties of aqueous extract (HAE) & it is possible mechanism, for Chlorophytum borivilianum tubers using BHV-1 and FMDV viruses as model viral agents.The mechanistic studies was done on its effect on IFN-γ and other cytokines induction in wistar albino rats. Prior to investigate antimicrobial and immunomodulatory activities non toxic dose of HAE of Chlorophytum borivilianum tuber was determined. None of experimental Wistar albimo rats in all the four experimental groups showed any clinical sign of illness. Results: In-vitro antiviral activity of HAE of Chlorophytum borivilianum tuber was characterized by the reduction in CPE and optical density produced by IBR and FMD viruses in MDBK and BHK-21 cell lines respectively under the influence of non toxic dose (MNTD) of HAE of Chlorophytum borivilianum tuber. For this, nontoxic dose of HAE of Chlorophytum borivilianum tuber was determined in MDBK and BHK-21 cell lines and found 1.25 mg/ml for IBR virus and 2.5 mg/ml for FMD virus, as MNTD, TCID50 was also calculated for the IBR and FMD viruses using MDBK and BHK-21cell line respectively which found 10 −2 and 10 −4 respectively. MNTD of HAE of Chlorophytum borivilianum tuber was used for the study of antiviral effect against IBR and FMD virus using 10 TCID50 conc. as challenging dose. No antiviral activity was found against IBR virus but antiviral activity was noticed against FMD virus. Percentage reduction in CPE found was 9.20/5.24/2.24% using medium containing 2.5/1.25/0.625 mg HAE/ml respectively. Antiviral activity was also estimated by O.D. using ELISA. Ex-vivo study of HAE of Chlorophytum borivilianum demonstrates that IFN-γ induction in rats fed with either of 250 mg or 500 mg/kg body wt. showed upregulation when measured using supernatant harvested from splenocytes grown with or without presence of ConA. However splenocytes harvested from rats treated with 1000 mg/1500 mg and induced suppression in the induction of IFN-γ even presence of ConA in respect to control.It was also confirmed by the PCR using previously published primers for IFN-γ cDNA amplification. Conclusion: Study concludes that the plant extract can be used as health intervention in fighting with few viral diseases by cytokine modulation, the detailed study on the cytokine stimulation (Which is under process) through extracts of Chlorophytum borivilianum can lead to the development of new concept in designing of antiviral drugs.

Fuzzy modeling and hybrid genetic algorithm optimization of virus removal from water using microfiltration membrane

Membranes are finding increasing applications in disinfection processes including virus removal from water for municipal effluent reuse. The capability of virus removal from water by microfiltration membranes has previously been demonstrated. In this study, the capability of fuzzy logic for modeling and simulation of dead-end microfiltration process for removal of IBR and FMD viruses from water was elucidated. The main parameters indicating membrane performance i.e. flux and rejection were experimentally obtained under different conditions and compared with theoretically calculated flux and rejection using fuzzy inference system. The genetic algorithm which is an efficient and systematic method was employed in the design of fuzzy model for optimization of the poorly understood, irregular and complex membership function with improved performance. Hybrid genetic algorithm was used for optimizing the parameters that are located at the Gaussian membership functions in the premise and consequent of each rule. The results indicated that fuzzy inference system predicts the key parameters i.e. flux and rejection for different operating conditions with an acceptable error. In other words FIS is able to apply for modeling the microfiltration membrane which is mathematically difficult or in many cases an unpredictable process.

Expression of infectious bovine rhinotracheitis virus glycoprotein D in bacterial cell

Bovine Herpesvirus 1 (BHV-1) belongs to the genus of Varicellovirus and the family of Herpesviridae which contains three main gB, gC and gD genes. In order to cloning of the coding region of gD gene of IBR virus , PCR product of the open reading frame of the gene from IBR virus isolated in Iran was amplified by PCR. A 1047bp PCR product of the gD gene with EcoRI, HindIII restriction sites were subcloned of pTZ57R/T and digested by the mentioned endonucleases. Digested insert cloned in to pET-32a and transfered in E.coli cells. For the expression of gD protein, the pET-32a recombinant vector was transformed and then induced in BL21 (DE3) strain of E.coli competent cells using IPTG. The presence of gD expressed protein was shown in immunoblotting and SDS-PAGE system. With respect to the remarkable frequency of infection to IBR in Iran and the necessity of controlling it through vaccination with recombinant vaccines of thymidine kinase, manufacturing and applying the recombinant gD protein are vital goals in recognition and distinction between infection and responses caused by vaccine.

Effect of a quadrivalent vaccine against respiratory virus on the incidence of respiratory disease in weaned beef calves

We investigated the effect of vaccination of male beef calves (mean age ± S.D.: 158 ± 31days) against bovine herpes virus (BHV-1 or IBR virus), bovine respiratory syncitial virus (BRSV), bovine viral diarrhea (BVD) virus and para-influenza (PI 3) virus on the incidence of respiratory disease during the first forty days after weaning and entering a feed-lot in Portugal. In May 2003, Mertolenga, Preta and mixed-breed calves from 10 different beef herds, were systematically assigned (by order of entrance in a chute) to two treatment groups, before moving to a common feed-lot. One hundred and twenty five male calves were vaccinated with a quadrivalent vaccine (Rispoval 4 ®) and revaccinated after 21–27 days while 148 herdmates were injected with saline (0.9% NaCl) on the same occasions. The incidence and severity of clinical cases of “bovine respiratory disease” (BRD) were evaluated every day during the first 40 days after entering the feed-lot. Morbidity (3% vs. 14%) and mortality (0% vs. 4%) due to BRD were significantly lower in the vaccinated group. Ten days after revaccination, the calves were treated with an antimicrobial – ending the study – after an outbreak of BRD caused a high incidence of disease in the non-vaccinated group. In conclusion, our results showed that Rispoval 4 ®, a quadrivalent vaccine against respiratory viruses, under field conditions, reduces morbidity and mortality due to BRD in beef calves after weaning.

Fenbendazole stimulates interferon secretion in calves during viral infection

A total of six trials (five with live animals and one in vitro study) were conducted to evaluate the effects of fenbendazole (FBZ) on the immune response in stressed feedlot cattle. FBZ was given to all treatment calves at the recommended label dosage of 2.3 mg/lb (5 mg/kg) body weight. In Trial 1, treatment with FBZ did not affect serum neutralizing (SN) virus titers or viral shedding following inoculation with live, avirulent bovine herpes virus (BHV-1), but did increase titers for interferon (IFN) in nasal secretions at one, four and seven days post-inoculation. In Trial 2, FBZ-treatment reduced viral shedding and increased IFN titer in nasal secretions on days 4, 7 and 11 following inoculation with live, virulent bovine viral diarrhea virus (BVDV). In Trial 3, treatment with FBZ increased average daily gain ( P =0.11) and increased IFN titer in nasal secretions at two ( P =0.12) and seven ( P =0.07) days following intranasal vaccination with avirulent BHV-1. In naturally infected calves, control and FBZ-treated calves had greater nasal secretions of IFN compared to calves treated with morantel tartrate, levamisole, or thiabendazole (Trial 4). Treatment with FBZ did not increase weight gain or interferon secretions in response to vaccination with IBR and BVD viruses (Trial 5). In cell cultures treated with bluetongue virus, FBZ increased IFN titers. FBZ appears to stimulate IFN secretion in calves during experimental infection with either BHV-1 or BVDV (Trial 6).

Observations on rinderpest and rinderpest-like diseases throughout West and Central African countries during rinderpest eradication projects

Between 1998 and 2005, the Regional Reference Laboratory at Bingerville (Ivory-Coast) received samples for analysis from Western and Central African countries. From a total of 606 sera; 65 tissue samples and 75 swabs received, no rinderpest virus or specific gene products or antibodies against rinderpest were detected. Use of the PCR on the tissue and swabs (total of 140 samples) identified the genomic presence of BVD (4/140), MCF (2/140), IBR (1/140) and FMD (6/140) viruses. These cause diseases that produce similar clinical signs to rinderpest. The quality of many samples sent to the reference laboratory did not meet the laboratory requirements and this compromised analysis of some specimens.

Evaluación de la prueba ELISA usando una cepa de campo como antígeno, para detectar anticuerpos contra el virus de la Rinotraqueitis Bovina Infecciosa

El siguiente estudio estableció un inmunoensayo enzimático ELISA, usando partículas virales fraccionadas de una cepa de campo del virus IBR, este mostró una alta sensibilidad y especificidad y una baja tasa de falsos negativos y positivos. Los sueros bovinos positivos y negativos, con los cuales se normalizó la técnica de ELISA, fueron analizados por seroneutralización para determinar anticuerpos anti IBR; se recolectaron sueros negativos y positivos con títulos 1:4 a 1:128 y se consideró la dilución del suero bovino 1:50, como la dilución óptima para la técnica de ELISA. Por otra parte, se utilizó el coeficiente de variación BR, para analizar el grado de repetitibilidad de las absorbancias obtenidas de los sueros positivos y negativos, se obtuvo resultados menores del 20%, lo que indico una adecuada repetitibilidad y un bajo coeficiente de variación.La sensibilidad y especificidad encontrada fue de 96 y 98% respectivamente, teniendo como prueba de referencia la seroneutralización. Los resultados obtenidos, determinan que la prueba de ELISA con partículas virales fraccionadas de una cepa de campo, detecta anticuerpos anti IBR con alta sensibilidad y especificidad, siendo una herramienta para el mejoramiento diagnóstico de la enfermedad.

Most frequent calf diseases in industrial breeding

It is possible to conduct an analysis of the incidence of viral diseases in calves if these diseases are divided into two basic groups. One group comprises diseases of respiratory organs which are manifested by symptoms of a respiratory syndrome, and the second group comprises diseases of digestive tract organs in the form of a gastrointestinal syndrome. It is considered that viruses have the dominant role in the complex etiology of the respiratory syndrome, primarily the IBR virus or the Bovine Herpes Virus-1 (BHV-1), followed by the parainfluenza 3 virus (RSV), the Bovine Viral Diahrrea Virus (BVDV), the bovine Respiratory Syncytial Virus (RSV), but also other viruses, such as adenoviruses, rhinoviruses, coronaviruses, can also influence the appearance of the respiratory syndrome. The respiratory syndrome is rarely caused by a single viral agent, but most frequently by mixed viruses, but also by bacterial infections. Mixed viral infections often have a lethal outcome. Investigations of the etiology of the gastrointestinal syndrome so far indicate that, in addition to bacteria, viruses can also be a significant etiological factor. Rotaviruses, coronaviruses, adenoviruses parvoviruses, herpesviruses (the IBR virus), pestiviruses (BVDV), can be the causes of a gastrointestinal syndrome. It is believed that viruses can be the cause in about 10% cases in the ethiopathogenesis of this syndrome. The paper describes the etiopathogenesis of calf diseases of viral etiology which are most often found in the local conditions of industrial breeding of calves.

Construction and characterization of a glycoprotein E gene-deleted bovine herpesvirus type 1 recombinant

Abstract Objective To construct and characterize a recombinant glycoprotein (g)E gene-deleted bovine herpesvirus (BHV) type 1 (BHV-1). Procedure The BHV-1 gE gene-coding region and the flanking upstream and downstream sequences were cloned. The aforementioned cloned DNA was digested with suitable enzymes to release the amino terminal two thirds of that region, and was ligated to the β-galactosidase (β-gal) gene. The resulting plasmid DNA was cotransfected with DNA from full-length, wild-type (WT), BHV-1 Cooper strain of the virus. Recombinant viruses expressing β-gal (blue plaques) were plaque purified and assayed further by blot hybridization for genetic characterization and by immunoblotting for reactivity against BHV-1 gE peptide-specific rabbit polyclonal antibody. One recombinant virus, gEΔ3.1IBR, was characterized in vitro and in vivo. The ability of the recombinant virus to induce BHV-1 neutralizing antibodies in infected calves was investigated by plaque-reduction tests. Results and Conclusions The gEΔ3.1IBR virus contained a deletion in the viral gE gene-coding sequences where a stable chimeric reporter (β-gal) gene was inserted. One-step growth kinetics and virus yield of the recombinant and parent viruses were similar, but early after infection, the recombinant virus yield was comparatively less. After intranasal inoculation, the recombinant gEΔ3.1IBR virus replicated in the upper respiratory tract of calves, but the amount of progeny viruses produced was hundredsfold reduced, and duration of virus shedding was shorter. Results of in vivo calf experiments and serum neutralization tests indicated that deleting the gE gene has little effect on inducing neutralizing antibodies against BHV-1, but is sufficient to reduce BHV-1 virulence in calves. (Am J Vet Res 1999; 60:227-232)

Priming the Immune System for IBR and BVD with One Dose of Killed Vaccine

A field trial was conducted in a cow/calf operation to evaluate the SN titer response to BVD and IBR virus following vaccination with either one or two doses of vaccines. Group 1 received two doses of vaccine. The first dose of vaccine was given 3 weeks prior to weaning and contained killed fractions of IBR and BVD. The second dose was given at weaning and was a four-way modified live vaccine (mlv) (IBR,BVD ,BRSV,PI3). Group 2 received only one dose of 4-way mlv vaccine at weaning. Group 3 was not vaccinated and remained with the herd as sentinels. SN titer results were compared to see if the antibody response elicited by a mlv could be primed with one dose of killed vaccine.&#x0D; The results from this trial indicate that one dose of killed vaccine, administered 3 weeks prior to a dose of mlv vaccine, effectively primed the immune response. The follow up dose of mlv vaccine administered at weaning elicited a rapid and elevated antibody titer response in Group 1 calves compared to Group 2 calves; an indication that priming had taken place.&#x0D; The findings in this study support a vaccination program tailored for the cow/calf operation where a priming dose of killed vaccine is given before weaning, with a follow up immunizing dose of mlv vaccine given at weaning.

SN Titer Response Comparisons Among Fourteen Diagnostic Laboratories for Antibodies Protecting Against IBR, BVD and BRSV Virus Following the Administration of Modified Live Vaccine to Weaning Aged Calves

Eleven yearling calves were vaccinated with BRSVVac® 41. Serum samples collected 35 days after vaccination were sent to 14 different diagnostic laboratories around the United States for assay of IBR, BVD and BRSV antibodies. A great deal of lab to lab variation was encountered. This variation was due in part to the virus strain used, lab technique and cell culture line utilized.

The Efficacy of an Inactivated IBR Vaccine in the Prevention of Intra-uterine Infection and its Use in a Disease-control Programme

The effects of administration of an established, inactivated IBR vaccine were studied in 30 cows from two herds (one seropositive and one seronegative). All acquired immunity which, after subsequent intratracheal infection with IBR virus, prevented development of symptoms in the cows and protected their foetuses against viral infection in utero. The calves were all healthy and were born at normal term. Ten non-vaccinated cows from the seronegative herd responded to the experimental infection with mild respiratory disease and abortion of four out of 10 foetuses. Organs from the aborted foetuses were found to have IBR virus. In a breeding herd, without clinical signs of disease but with 40% of cows tested as seropositive, a 2-year disease-control programme was initiated. A total of 234 newborn calves were examined and it was shown that immunization of their dams with an inactivated vaccine conferred full in utero protection against IBR-virus infection. When such calves are reared in isolation they can be used as the nucleus for a seronegative breeding herd.

Clinical response of feeder calves under direct IBR and BVD virus challenge

The effects of 2 virus vaccines on morbidity and mortality in autumn weaned feeder calves was evaluated. Treatment I cattle received a multivalent vaccine consisting of chemically altered IBR and PI3, viruses, a modified live BRSV, an inactivated BVDV, and a bacterin containing 5 Leptospira interrogans serovars (canicola, grippotyphosa, hardjo, icterohaemorrhagiae, and pomona (Cattle Master 4 + L5TM)). Treatment II cattle received an all killed virus IBTBFD-PI3-BRSV and a bacterin containing 5 L. interrogans serovars. Treatment III cattle were not vaccinated. All animals were subjected to direct aerosol challenge with virulent IBR and BVD virus 30 days after booster vaccination. The non-vaccinated group was included to provide a measure of the severity of challenge, and to serve as a basis of comparison for the vaccinated groups. All cattle were sero-negative for IBR and BVD prior to initiation of the study. The 2 vaccinated groups (Treatment I and II) received primary and booster inoculations prior to virus challenge. The control group (Treatment III) remained sero-negative to IBR and BVD until challenge. Treatment I calves experienced a morbidity rate of 8% and no mortality. Treatment II calves experienced a morbidity and mortality of 13%. Morbidity and mortality in Treatment III calves were 100% and 58% respectively. A statistically significant reduction in morbidity and mortality was demonstrated in vaccinated calves versus non-vaccinated calves. A significant reduction in morbidity and mortality was also demonstrated in the calves that received the chemically altered virus, MLV, and killed virus combination vaccine as compared to the calves that received the all killed virus vaccine. The authors conclude this study supports the use of combination virus vaccines for the control of IBR and BVD induced respiratory disease in autumn weaned calves.

Enquête sérologique concernant les virus IBR, CHV2, BVD, PI3, RSB et bovipesti que chez les petits ruminants au Zaïre

Une enquête sérologique a été réalisée sur plus de 400 sérums de petits ruminants du Zaïre envers les virus IBR, CHV2, BVD, PI3 bovin et ovin, RSB et bovipestique. Les sérums des animaux indigènes sont négatifs pour les virus BVD, PI3 et celui de la peste bovine; 8 p. 100 des sérums sont positifs pour le virus IBR et présentent tous des titres supérieurs envers le CHV2, 31 p. 100 des sérums sont positifs pour le virus RSB.

Immune response of fasted calves to infectious bovine rhinotracheitis virus.

Seventeen calves (Angus, Hereford, and Angus-Hereford crosses) weighing 120-200 kg, were starved for 3 days and inoculated intranasally with a strain of IBR virus after 1 day or 3 days of food deprivation. Although clinical signs of disease were mild in all calves, the signs appeared more severe than those reported by others using the same strain of virus possibly due in part to the use of intranasal inoculation by aerosol vs instillation. Neutralizing antibody response after virus inoculation did not differ beween groups. Of the 17 calves, 16 developed significant increases (seroconversion of 4-fold increase in titre) in IBR serum antibodies. Serum neutralizing antibodies in 3 calves at inoculation did not prevent them from excreting substantial amounts of virus for ? 5 days after virus inoculation. Lymphocytes from fasted and nonfasted calves had similar (essentially negative) blast transformation responses, except 1 fasted seropositive calf (sensitised animal) that had a high stimulation index. Some dehydration was observed in fasted calves, indicated by significant increase in haematocrit. In only 1 group did serum cortisol levels rise significantly, mean values peaking at the end of fasting at the time of inoculation; thereafter, mean values tended to decline. Although the 3-day fast significantly affected some serum and blood components, it did not adversely affect the immune response of calves. One fasted calf developed a significant cell mediated immune response to inactivated IBR virus during infection. It is concluded that acute nutritional deprivation may not necessarily increase the susceptibility of calves to viral infections nor adversely affect their immune response after vaccination.&#x0D; This report represents a portion of a dissertation submitted by the senior author to the graduate faculty of the University of Missouri in partial fulfillment of the requirements for the PhD degree.&#x0D; The authors thank Gary Krause and Mark Ellersieck for aid in statistical analysis and Gerald Buening for help in lymphocyte transformation tests.