Duration of protection of calves against rhinovirus challenge exposure by infectious bovine rhinotracheitis virus-induced interferon in nasal secretions

Six calves inoculated intranasally with a vaccinal strain of infectious bovine rhinotracheitis (IBR) virus and 6 control calves were given a placebo. All calves were subsequently challenge exposed (by aerosol) with rhinovirus--3 of the calves from each group at 2 days after they were inoculated with IBR virus or with placebo and the remaining calves at 6 days. Nasal excretion of viruses, interferon (IFN) concentrations in nasal secretions (NS), and neutralizing antibody in sera and NS were determined. All calves given the vaccinal IBR virus subsequently had IFN in their NS. Interferon was detected as early as 1 day, reached maximal titers at 2 to 4 days, and persisted in individual calves for 5 to 10 days after inoculation. Rhinovirus shedding was not detected from IBR virus-inoculated calves whose NS contained both rhinovirus antibody and IFN at the time of challenge exposure; such calves were protected at either 2 or 6 days after IBR virus inoculation. The outcome of rhinovirus challenge exposure of calves whose NS contained IFN, but not rhinovirus antibody, varied with the day of challenge exposure. Rhinovirus excretion was detected from 2 of these calves challenge exposed 2 days after IBR virus inoculation, but was not detected from a calf challenge exposed 6 days after inoculation. However, while IFN was present in NS from the former 2 calves, rhinovirus shedding was markedly reduced as compared with that from control calves without IFN or NS antibody at the time of challenge exposure. Consistent relationship was not observed between the rhinovirus neutralizing antibody titer of calves' sera and NS. The antibody titer of NS more closely correlated with protective immunity to rhinovirus infection than did the serum antibody titer.     

In utero infection of swine fetuses with infectious bovine rhinotracheitis virus (bovine herpesvirus-1)

The pathogenesis of infectious bovine rhinotracheitis (IBR) virus (bovine herpesvirus-1) was studied in porcine fetuses after in utero inoculation. Laparotomies were performed on 8 seronegative pregnant sows at 34 to 86 days of gestation, and all fetuses in 1 uterine horn of each sow were exposed to IBR virus via inoculation into the amniotic sacs. Fetuses in the other horn served as controls. Clinical signs of infection were not observed in the sows, except for 2 sows that aborted at postinoculation days (PID) 11 and 15. Fetuses of the remaining 6 sows were collected at slaughter on PID 15 to 28. Fetuses were examined for gross abnormalities, presence of IBR virus in tissues, and the formation of neutralizing antibodies to IBR virus. Of 33 inoculated fetuses from 6 sows, 10 were mummified, 11 were hemorrhagic and/or edematous, and 12 were alive. Necrotic lesions were observed on the skin and in the liver of dead and live fetuses. Virus was recovered from 29 of 33 inoculated fetuses. Infectious bovine rhinotracheitis virus was isolated from fetal skin, liver, lungs, kidney, spleen, stomach contents, brain, amniotic fluid, and placenta. Virus was isolated from 4 of 11 fetuses recovered from 1 aborting sow. Antibodies to IBR virus were not detected in sera from the sows. However, antibodies were detected in 6 of 15 fetuses inoculated at 63 to 86 days of gestation and collected at slaughter at 86 to 112 days of gestation. The youngest fetus with detectable IBR antibody was estimated to be 74 days of gestation by measuring crown-rump length of the fetus.     

Ovarian lesions in heifers exposed to infectious bovine rhinotracheitis virus by non-genital routes on the day after breeding

Twelve heifers were exposed to either a Colorado infectious bovine rhinotracheitis (IBR) virus isolate or an Iowa IBR isolate obtained from a bovine respiratory disease outbreak. All inoculations were made on the day after the heifers had been in estrus and bred by an IBR virus-negative bull. Pairs of heifers were inoculated with each virus isolate intravenously, intramuscularly or exposed by aerosol. The heifers were killed 11-15 days after inoculation and their reproductive tracts and ovaries subjected to virological and pathological study. Virus was isolated from the ovaries of all 4 heifers inoculated intravenously and from 3 of the 4 heifers inoculated intramuscularly, but not from the ovaries of heifers exposed by aerosol. Virus isolations and lesions were, with only 1 exception, confined to the ovary containing the corpus luteum. In ovaries from which IBR virus was isolated, lesions in the corpus luteum ranged from focal necrosis and infiltration of mononuclear cells to diffuse hemorrhage and necrosis. Most of these ovaries also had necrotic follicles and a diffuse mononuclear cell accumulation in the stroma. Lesions were not found in ovaries from which IBR virus was not isolated. It was concluded that lesions are readily induced in the ovaries of post-estrus heifers as a result of hematogenous spread of IBR virus and suggest that the differences in lesion development observed with the 3 routes are related to whether or not a viremia occurred.     

Comparison of the immunizing effectiveness of subunit vaccine and inactivated viral oil vaccine against infectious rhinotracheitis of cattle

Trials were conducted on rabbits and cattle to compare the immunizing effectiveness of the subunit vaccine against infectious bovine rhinotracheitis (IBR), representing antigens separated by the solubilization of the IBR virus-infected cells by means of Triton X-100 with oil adjuvant, with the inactivated oil IBR vaccine. The rabbits inoculated and re-vaccinated with both vaccines in an interval of three weeks produced neutralizing antibodies in medium titres, the values of these antibodies were balanced in both groups. Cattle immunized with the subunit vaccine reacted to the inoculation and re-vaccination by producing serum antibodies of higher titres, as compared with the cattle inoculated with the virus vaccine; secretory antibodies were detected only after re-vaccination and had balanced values in both test groups. After intranasal infection with the virulent virus performed after 14 days from re-vaccination, the calves inoculated with the subunit and virus vaccines were protected against clinical disease whereas the non-inoculated control calves fell ill with symptoms characteristic of IBR. The immunized animals of both experimental groups had a smaller amount of virus p.i. in nasal secretions and for a shorter time than the control non-inoculated calves. The intensity of multiplication and persistence of infectious virus excretion were the same in both experimental groups.     

Subclinical breakdown with infectious bovine rhinotracheitis virus infection in dairy herd of high health status

Infectious bovine rhinotracheitis (IBR) virus infection was detected by an antibody ELISA in the bulk milk of a large closed dairy herd of high health status in an area of low cattle density in East Anglia. The herd was managed under high standards of biosecurity and was known to have been serologically free of IBR virus for the previous 13 years. Although over 70 per cent of the cows had seroconverted to IBR virus no clinical signs were observed apart from a slight bilateral watery ocular discharge in a few cows, and their performance and productivity were unaffected. The causal virus, which was isolated after it had been reactivated with corticosteroid, had the DNA profile of a bovine herpesvirus type 1 strain normally associated with clinically severe respiratory disease. In spite of extensive enquiries and seroepidemiological investigations the source of the infection was not determined.     

Periocular dermoid cyst in a calf

Serum samples (n = 1,146) representing 100 species of exotic ruminants now captive in United States zoos were assayed for neutralizing antibody to infectious bovine rhinotracheitis (IBR) virus (bovine herpesvirus 1). Thirty-four animals (3%) of 11 species had antibody to IBR virus. Because of the low prevalence of IBR antibody found, it was concluded that vaccination against IBR virus probably is not necessary for captive wild ruminants in United States zoos.     

Neural changes in vaccinated calves challenge exposed with virulent infectious bovine rhinotracheitis virus

Recurrent infection in calves vaccinated with infectious bovine rhinotracheitis-(IBR) modified live virus was induced by dexamethasone (DM) treatment given 49 days after challenge exposure with virulent IBR virus. Nonchallenge-exposed IM and intranasally vaccinated calves did not excrete the virus after DM treatment; however, IM and intranasally vaccinated and subsequently challenge-exposed calves excreted the challenge-exposure virus into the nasal secretions 5 to 11 days and 6 to 10 days after the DM treatment, respectively. The calves were killed 15 to 18 days (experiment 1) and 14 days (experiment 2) and DM treatment was started and then were examined by histopathologic and fluorescent antibody techniques. All DM-treated calves that were inoculated with the vaccinal virus and challenge exposed with the virulent virus developed nonsuppurative trigeminal ganglionitis and encephalitis. On the contrary, the DM-treated nonchallenge-exposed vaccinated calves did not have lesions in the peripheral nervous system and CNS. Infectious bovine rhinotracheitis virus antigens were not observed in tissues of any of the calves examined (experiments 1 and 2) by fluorescent antibody techniques. These observations indicated that the modified live IBR virus neither produced lesions nor induced latent infection and that modified live IBR virus vaccination did not protect the calves against the establishment of a latent infection after their exposure to large doses of the virulent IBR virus.     

THE SUSCEPTIBILITY OF CALVES TO INFECTION WITH A STRAIN OF BOVINE EPHEMERAL FEVER VIRUS INOCULATED INTRACEREBRALLY

Three newborn calves were inoculated intracerebrally with bovine ephemeral fever virus strain 525. The 2 that lacked detectable neutralising antibody to bovine ephemeral fever vaccine developed fatal encephalitis after 4 and 7 days respectively. The third calf which had a low level of maternal antibody remained healthy and developed antibody that became undetectable after 6 months. Bovine ephemeral fever virus strain 525 was reisolated from the brains of both dead calves by intracerebral inoculation of suckling mice. Homogenates that were prepared from the brains of the calves failed to produce disease or to induce antibody formation in susceptible calves when inoculated intravenously. Strain 525 of BEF virus has been shown to possess a degree of neurovirulence for laboratory animals that has not been reported for other strains (Tzipori and Spradbrow 1974). Although this strain is unable to produce viraemia in calves after I/V inoculation, the present study shows that strain 525 can multiply in the brain tissues of calves and cause death after I/C inoculation.     

Investigation of causative agents of bovine respiratory tract disease in a beef cow-calf herd with an early weaning program.

Serum samples were collected from early weaned fall calves shortly after the onset of respiratory tract disease. Antibody titers to infectious bovine rhinotracheitis (IBR) virus, parainfluenza type 3 (PI-3) virus, bovine viral diarrhea (BVD) virus, bovine adenovirus type 3 (BAV-3), and bovine respiratory syncytial virus (BRSV) were determined on paired (acute and convalescent) serums. Seroconversion rate (a fourfold or greater rise in antibody titer) for IBR virus was 4.3%, PI-3 virus--16.3%, BVD virus--9.6%, and BAV-3--2.2%. Seroconversion for BRSV was 45.4%. An increased rate of seroconversion for IBR, PI-3, and BVD viruses and BAV-3 was observed in the presence of BRSV seroconversion. These results suggest that BRSV may facilitate infection by other viruses. Results of virus isolation procedures from these calves were negative.     

Leukocyte changes and interferon production in calves injected with hydrocortisone and infected with infectious bovine rhinotracheitis virus.

Correlations between leukocyte counts and serum interferon titers were determined in calves given hydrocortisone (HC) and infectious bovine rhinotracheitis (IBR) virus. Calves were injected with either 1 mg or 3 mg of HC/kg of body weight every 8 hours for a total of 9 injections each. Control calves were given placebo injections. Viral inoculation was given IV 10 hours after the 1st dose of HC or placebo was given. By the time of viral inoculation, all calves injected with HC had developed neutrophilia, and the calves injected with 3 mg of HC also developed leukocytosis, lymphopenia, and eosinopenia; total leukocyte counts in calves injected with 1 mg of HC were increased, but not as much as in other HC-treated calves. Leukocyte counts in calves given placebo remained essentially unchanged before viral inoculation. At 1 day after IBR virus was inoculated, the number of circulating lymphocytes in HC-treated calves and control calves was decreased by more than 50%, on the average, of the counts taken before the HC injections or inoculation of virus. A significant negative correlation existed between the numbers of circulating lymphocytes and serum interferon titers at 1, 2, and 3 days after inoculation with IBR virus. The interferon response of calves undergoing lymphocyte suppression due to HC was not impaired, but was enhanced.     

Active and Passive Immunity to Bovine Viral Respiratory Diseases in Beef Calves After Shipment

Fifteen steers were vaccinated after shipment with a modified live virus vaccine containing infectious bovine rhinotracheitis (IBR), bovine virus diarrhea (BVD), and bovine myxovirus parainfluenza-3 (PI3), and 16 unvaccinated steers were kept as controls. Geometric mean titers one month after vaccination were highest to BVD, followed by PI3 and IBR. Weight gains were higher during 30 days after vaccination in the controls. One case of acute respiratory disease developed in one vaccinated calf. Revaccination 79 days after the first dose increased antibody to PI3 and BVD virus but not IBR. In a second trial, no clinical respiratory disease developed after shipment of 13 heifers that received an antibacterial-antiviral antiserum or in the 12 controls. Weight gains 30 days after shipment were identical in both groups.     

In vitro interferon production by bovine tissues: induction with infectious bovine rhinotracheitis virus.

The interferon-inducing ability of infectious bovine rhinotracheitis (IBR) virus was determined in tissue cultures of bovine origin inoculated with untreated and ultraviolet (UV) irradiated IBR viruses. Interferon was assayed by the plaque-reduction method in bovine fetal kidney (BFK) cell cultures, using vesicular stomatitis virus as challenge virus. Highest interferon concentrations were produced by cultures of bovine fetal (BF) spleen cells and aveolar macrophage cultures derived from adult cattle. Moderate interferon concentrations were produced by peripheral blood leukocyte (PBL) suspension cultures from adult cattle with serum-neutralizing antibodies against IBR virus. Cultures of PBL from 1 cow without detectable serum-neutralizing antibodies against IBR virus did not produce detectable interferon in response to IBR virus. Cultures of PBL from cattle with or without detectable serum-neutralizing antibodies against IBR virus produced interferon when stimulated with phytohemagglutinin (PHA). Low levles of viral inhibitors were detected infrequently in monolayer cultures of BFK and BF nasal mucosa inoculated with UV-irradiated IBR virus and in BF tracheal organ cultures inoculated with untreated IBR virus. Interferon was not detected in fluids collected from IBR virus-exposed monolayer cultures of primary and secondary BF lung, secondary BF tracheal mucosa, secondary BF liver, secondary BF adrenal, and PBL in the 4th and 7th passages. The antiviral inhibitors from BF spleen, bovine alveolar macrophage, and PBL cultures induced with IBR virus, as well as inhibitors from PBL cultures induced with PHA, had the usual properties of interferon.     

Experimental transmission of bovine viral diseases by insemination with contaminated semen or during embryo transfer

Three experimental approaches were used to study transmission of blue tongue (BT), infectious bovine rhinotracheitis (IBR) and bovine virus diarrhoea (BVD) viruses. These were insemination with contaminated semen, experimental infection of embryo donor cows, or transfer of embryos experimentally exposed to virus in vitro to normal recipients. Parameters assessed included number and quality of embryos produced, virus detection (isolation and electron microscopy), serology and histopathology. All superovulated sesceptible cows inseminated with semen containing blue tongue virus (BTV) (n = 2) or infectious bovine rhinotracheitis virus (IBRV) (n = 2) became infected. One cow inseminated with semen containing BTV produced seven virus-free seven-day-old embryos; the second cow failed to produce any embryos. One of two cows inseminated with semen containing IBRV produced two underdeveloped, virus-free embryos while no embryos were produced by the second cow. One of two cows inseminated with semen containing bovine viral diarrhoea virus (BVDV) became infected. Two poorly developed, virus-free seven-day-old embryos were recovered from one of these cows. Superovulated susceptible cows inoculated either intramuscularly with BTV (n = 3) or intranasally with IBR virus (n = 2) became infected. Virus was isolated from some tissues of two BTV-infected cows, neither of which produced embryos. A third BTV-infected cow produced two virus-free embryos collected at necropsy five days after inoculation. One of two cows experimentally infected with IBR virus, produced three embryos but virus was not detected either by electron microscopy (1 embryo) or in cell culture by cytopathic alterations (1 embryo).(ABSTRACT TRUNCATED AT 400 WORDS)     

Neural changes in recurrent infection of infectious bovine rhinotracheitis virus in calves treated with dexamethasone.

Recurrent infection by infectious bovine rhinotracheitis (IBR) virus was induced in calves by dexamethasone (DM) treatment (given 5 days) at 5 months after primary infection. The virus appeared in nasal secretions of the calves on the 4th day after initiation of DM treatment and continued until the 9th day. The calves were killed on the 1st, 3rd, 4th, 5th, 6th, 7th, 8th, 10th, and 11th days after DM treatment was started for examination by histopathologic and immunofluorescent antibody techniques. The most significant neural change was trigeminal ganglionitis with neuronophagia, which was observed from the 3rd to the 11th day. Significantly, the extent of changes in the trigeminal ganglion and medulla oblongata corresponded to the amount of DM treatment administered. The IBR virus antigen was first observed in the trigeminal ganglion cells, and thereafter, it was detected in the Schwann cells, satellite cells, neuroglia cells, and nasal mucosa until the 10th day. These observations indicate that the IBR virus is capalbe of producing a persistent infection in the trigeminal ganglion and that trigeminal ganglionitis may be a characteristic lesion for inducing the reactivation of lagent IBR virus.     

牛传染性鼻气管炎病毒的分离鉴定与灭活疫苗免疫效果研究

由2例疑似牛传染性鼻气管炎（IBR）病例的荷斯坦奶牛分离到一株病毒,命名为IBRV—C1株。该病毒可被IBR标准阳性血清完全中和;接种MDBK细胞可出现IBR病毒典型细胞病变效应;选取IBR病毒gB蛋白基因序列设计引物进行PCR检测和基因测序,结果可扩增出特异性目的片段;动物回归试验显示,3头牛均可见体温升高、鼻流粘液、呼吸困难等典型的IBR临床症状。在此基础上制备了三批牛传染性鼻气管炎灭活疫苗,并进行了疫苗安全性和效力试验,结果表明三批疫苗对靶动物安全,免疫效果较好,免疫牛中和抗体效价几何平均值可达1：41以上,攻毒保护率达5／5。     

Infectious bovine rhinotracheitis virus: studies on the venereal carrier status in range cattle.

Genital samples collected at autopsy from 193 beef cows representing 22 different herds in Northern Australia yielded only one isolate of infectious bovine rhinotracheitis (IBR) virus. Serological evidence showed 59 per cent of similar cows had prior infection with this virus and of 19 sero-positive cows tested, 11 (58-2 per cent) shed detectable IBR virus from the vagina after treatment with corticosteroids. Transitory lesions of the vagina and vulva developed in five of the treated cows. Twenty-six (65 per cent) of 40 sero-positive bulls shed detectable IBR virus into the prepuce after corticosteroid treatment. Except for one bull, virus was not isolated after corticosteroid treatment of sero-negative animals. IBR virus and mucosal disease (MD) virus were not isolated from nasal swabs before or after corticosteroid administration. No correlation was observed between initial circulating antiboyd titre and virus excretion after treatment. There were no significant changes in levels of serum antibody during the virus excretion period.     

ISOLATION AND CHARACTERISATION OF BOVINE HERPESVIRUS MAMMILLITIS VIRUS AND ITS PATHOGENICITY FOR CATTLE

Ten viruses isolated from swabs and vesicular fluid collected from the teats of dairy cattle on 4 properties in Northern Victoria were identified as bovine herpes mammillitis (BHM) viruses by their physico-chemical and morphological properties and serological relationship to each other and a Scottish Strain of BHM virus. The viruses, isolated in bovine kidney and testicular cell cultures, produced cytopathic effects characterised by very large syncytia and eosinophilic intranuclear inculsion bodies. The intradermal inoculation of BHM virus into two cattle produced necrosis and ulceration of the skin of the teats about the area of inoculation and the development of serum neutralising antibody. After healing of the ulcers on day 37 after inoculation, the cattle were intravenously inoculated with corticosteroid for 6 days but BHM virus was not re-isolated from the teat skin or vaginal or nasal swabs.     

Isolation of bovine herpesvirus III from diarrheic feces

A herpesvirus was isolated from the feces of a cow with diarrhea. The viral isolate was identified as a herpesvirus on the basis of morphology and chloroform sensitivity. It was serologically distinct from bovine Herpesvirus I (IBR) and II (mammillitis virus) as well as equine herpesviruses and pseudorabies virus. It was serologically related to members of the bovine Herpesvirus III group.Experimentally inoculated calves developed a transient fever but no other clinical signs or lesions. The virus could be re-isolated from the calves and significant levels of virus neutralizing antibodies were present in the serum 40 days after inoculation.     

新疆某规模化奶牛场牛传染性鼻气管炎病毒抗体水平检测

为了调查新疆地区某规模化奶牛场牛传染性鼻气管炎（IBR）发病情况,通过采集不同生长阶段牛群血清共计362 份,使用牛传染性鼻气管炎病毒gB（IBR-gB）抗体检测试剂盒检测牛传染性鼻气管炎病毒（IBRV）抗体效价,评估该奶牛场IBRV疫苗免疫效果。结果显示,后备牛中犊牛和青年牛IBRV抗体阳性率分别为88.57%（31/35）、75.00%（21/28）;成年母牛中泌乳期母牛、干奶期母牛IBRV抗体阳性率分别为81.46%（145/178）、95.04%（115/121）。阴性数共44 份,可疑数8 份,IBRV抗体平均阳性率为88.38%;结果表明,疫苗接种后,不同生产阶段牛群均可产生不错的抗体保护效果,为奶牛场防控IBR提供依据。     

The isolation and characterization of a strain of infectious bovine rhinotracheitis virus from stillbirth in swine.

A virus, designated 5089, which was isolated from tissue samples from two stillborn pig fetuses was identified on the basis of its morphology, cytopathology, physiocochemical and serological characteristics as a strain of infectious bovine rhinotracheitis (IBR) virus. Three piglets inoculated intranasally with 5089 virus did not respond serologically and no virus was isolated from their tissues at intervals after inoculation. They showed neither clinical signs nor significant lesions. A colostrum deprived calf which was inoculated intranasally with the same virus developed clinical signs typical of the respiratory form of IBR and the virus was reisolated on several occasions from nasal swabs.