Hydranencephaly-cerebellar hypoplasia in a newborn calf after infection of its dam with Chuzan virus

Chuzan virus at 2 to 3 passage levels in cell cultures after isolation was inoculated intravenously into 15 seronegative pregnant cows at 89 to 150 days of gestation. All of the cows developed viremia a few days after inoculation and antibodies 2 weeks after inoculation. No clinical signs, except leukopenia, were observed throughout the experimental period. These 15 cows delivered 15 calves after normal gestation. One of the calves which was born to a dam inoculated at 120 days of gestation, showed impairment of movement, and the remaining 14 were healthy. Postmortem examination revealed that this calf had hydranencephaly- cerebellar hypoplasia (HCH) syndrome and that the remaining calves were normal. Two of the 15 calves, including the one that had HCH syndrome, had antibody to Chuzan virus in their precolostral sera. These findings provide additional evidence that Chuzan virus is the etiological agent of an epizootic of congenital abnormalities with HCH syndrome of calves in Japan, 1985 to 1986. We propose to name the HCH syndrome caused by Chuzan virus infection Chuzan disease.     

Isolation of Chuzan virus, a new member of the Palyam subgroup of the genus Orbivirus, from cattle and Culicoides oxystoma in Japan

Five virus strains with identical antigenic properties were isolated from 3 RBC suspensions obtained from 2 healthy sentinel calves and from 2 pools of Culicoides oxystoma in cultures of a hamster lung cell line (HmLu-1). The virus was tentatively named Chuzan virus. The Chuzan virus was classified as a new member of the Palyam subgroup of the genus Orbivirus on the basis of its physicochemical, morphologic, and antigenic properties.     

Sero-survey on Aino, Akabane, Chuzan, bovine ephemeral fever and Japanese encephalitis virus of cattle and swine in Korea

Vector-borne arboviruses produce mild to severe symptoms in domestic animals. Bovine ephemeral fever (BEF), Akabane, Aino, and Chuzan virus have been primarily attributed to reproductive disorders or febrile diseases in cattle, and Japanese encephalitis virus (JEV) is mainly associated with reproductive failures in swine. We investigated antibody titers from domestic swine against four bovine arboviruses (BEF, Akabane, Aino, and Chuzan virus) and from cattle against JEV in Korea. While the positive rates for Akabane and BEF were 37.4% and 15.7%, the positive incidence of Chuzan and Aino were relatively low, with positive rates of 3.04% and 0.4%, respectively, based on a virus neutralization assay. Antibody titers against more than one virus were also frequently detected in domestic swine. The incidence of JEV was 51.3% among domestic cattle. In addition, one positive case was detected in the thoracic fluids from 35 aborted calves, based on the hemagglutination inhibition test. Our results indicate that swine are susceptible hosts of bovine arboviruses without showing clinical symptoms in a natural environment. Moreover, we confirmed that JEV could be associated with reproductive failure in pregnant cattle, as were other vector-borne bovine arboviruses assessed in this study.     

Clinical and immunologic responses of calves with colostrally acquired maternal antibody against parainfluenza-3 virus to homologous viral infection.

Exposure of colostrum-deprived calves and calves with colostrally acquired maternal antibody to aerosols of parainfluenza-3 (PI-3) virus resulted in signs of infection, leukopenia, and shedding of virus from the nasal passages. However, infection was not as severe in calves with colostrally acquired maternal antibody as it was in colostrum-deprived calves which did not have antibody to PI-3 virus before they were exposed. All calves responded immunologically to PI-3 virus, as indicated by resistance to challenge exposure and subsequent development of virus-neutralizing antibody. However, levels of serum and nasal secretion (NS) antibody at 30 days after viral exposure were lower in calves with colostrally acquired maternal antibody than in colostrum-deprived calves, and a serum antibody response in the former was primarily indicated by an anamnestic response after challenge exposure. After calves were challenge exposed to PI-3 virus, serum and NS antibodies were increased in all calves, but antibody titers were generally lower for calves that had colostrally acquired maternal antibody before their exposure than for those that acquired antibody only after PI-3 viral infection.     

Evaluation of the pathogenic potential of cervid adenovirus in calves.

Four 3-month-old Jersey calves and three 3-month-old Holstein calves were inoculated with cervid adenovirus and monitored for clinical signs until necropsied between 10 and 42 days postinoculation. The neonatal Jersey calves had received colostrum, and the Holstein calves were colostrum deprived. Preinoculation and postinoculation serum samples were tested for antibodies to the cervid adenovirus, bovine adenovirus type 6, bovine adenovirus type 7, and goat adenovirus type 1. Virus isolation was performed on kidney, nasal secretion, and/or lung homogenates in fetal white-tailed deer lung cells. Negatively stained preparations of feces from Jersey calves were examined weekly using an electron microscope, and weekly blood samples were collected for complete blood counts. Full necropsies were performed on all calves. A complete selection of tissues was evaluated for microscopic changes, and immunohistochemistry was performed on all tissues using a polyclonal antibody to deer adenovirus. No clinical signs were observed in the calves during the study period. Following inoculation, colostrum-deprived calves developed low antibody titers to deer adenovirus, while the Jersey calves that received colostrum did not. Calves that received colostrum had high antibody titers to bovine adenovirus type 7 and goat adenovirus type 1. No consistent gross or microscopic lesions were seen. Adenovirus was not observed in negatively stained preparations of feces. Immunohistochemistry results did not demonstrate virus in all tissues examined microscopically, and virus was not isolated from lungs, nasal secretions, and kidneys.     

Interferon, fluorescent antibody, and neutralizing antibody responses in sera of calves inoculated with bovine respiratory syncytial virus

Interferon, fluorescent antibody, and neutralizing antibody responses were studied in sera of 9 calves inoculated with bovine respiratory syncytial virus, in relation to viral shedding and clinical signs of disease. The calves (5.5 to 6.5 weeks of age) were assigned to 3 groups. Group I was inoculated once with the virus, and groups II and III were challenge exposed at postinoculation day (PID) 15 or 37. Serum-neutralizing and indirect fluorescent antibody techniques were used to measure antibody responses. The plaque-inhibition technique, using vesicular stomatitis virus, was applied to measure serum interferon titers. The virus was recovered by inoculation of nasal secretions onto cell cultures. Fluorescent antibody was detected in all calves on PID 3, with maximum titers appearing approximately on PID 10. Low neutralizing antibody was detected in most animals on PID 3, and titers peaked approximately 4.5 weeks after inoculation and then decreased. Interferon titers were high in all calves during the early stage of infection, dropped to undetectable amounts by PID 6, and reappeared in low amounts at least 1 week later. All infected calves manifested clinical signs of disease by PID 4 to 9. Clinical signs of disease were not observed after challenge exposure at PID 15 or 37, and anamnestic responses were not detected. Virus was recovered after challenge exposure at PID 15, but not at PID 37.     

An outbreak of congenital hydranencephaly and cerebellar hypoplasia among calves in South Kyushu, Japan: a pathological study

An outbreak of congenital hydranencephaly and cerebellar hypoplasia occurred between November 1985 and May 1986 in Miyazaki, South Kyushu, Japan. Seventy-three calves had nervous signs of varying severity such as inability to stand, locomotor difficulties, defective vision and difficulty in sucking. At necropsy, 62 calves had macroscopic lesions in the central nervous system: hydranencephaly accompanied by cerebellar hypoplasia in 47; hydranencephaly alone in eight; and dilatation of the lateral ventricle in seven; none had arthrogryposis. Microscopically, all 62 cases involved various degrees of hypoplasia of neural components, such as total or partial thinning of the cerebral or cerebellar laminae. Heterotopia, such as abnormal islands of granule cells or Purkinje cells was also observed. Fourteen of these animals had other lesions such as non-purulent encephalitis, focal gliosis, neuronal degeneration, calcification or pseudocalcification, and cholesterol deposits, activation of vascular endothelial cells and haemorrhage. From the findings, these cases were considered to represent mainly hypoplasia of nerve tissue due to infection with a virus different from Akabane virus.     

Hemagglutination and hemagglutination inhibition with Chuzan virus.

Chuzan virus agglutinated erythrocytes of several species of animals including bovine. The hemagglutinating (HA) activity against bovine erythrocytes was dependent on NaCl molarity and was expressed best at 0.6 M, but it was independent of pH and temperature. Three strains of Chuzan virus isolated from 2 cows and a pool of culicoides midges had indistinguishable HA antigenicity. All cattle infected with the virus developed high titers of hemagglutination inhibiting (HI) antibody which changed in parallel with neutralizing (NT) antibody titers. Correlation between HI and NT antibodies was very high and the antibodies persisted for one year or more. Therefore it was concluded that the HI test is applicable for survey of Chuzan virus infection among cattle in place of the NT test.     

Efficacy of an inactivated respiratory syncytial virus vaccine in calves.

OBJECTIVE: To determine whether an inactivated bovine respiratory syncytial virus (BRSV) vaccine would protect calves from infection with virulent BRSV. DESIGN: Randomized controlled trial. ANIMALS: 27 nine-week-old calves seronegative for BRSV exposure. PROCEDURE: Group-1 calves (n = 9) were not vaccinated. Group-2 calves (n = 9) were vaccinated on days 0 and 21 with an inactivated BRSV vaccine containing a minimum immunizing dose of antigen. Group-3 calves (n = 9) were vaccinated on days 0 and 21 with an inactivated BRSV vaccine containing an amount of antigen similar to that in a commercial vaccine. All calves were challenged with virulent BRSV on day 42. Clinical signs and immune responses were monitored for 8 days after challenge. Calves were euthanatized on day 50, and lungs were examined for lesions. RESULTS: Vaccination elicited increases in BRSV-specific IgG and virus neutralizing antibody titers and in production of interferon-gamma. Virus neutralizing antibody titers were consistently less than IgG titers. Challenge with BRSV resulted in severe respiratory tract disease and extensive pulmonary lesions in control calves, whereas vaccinated calves had less severe signs of clinical disease and less extensive pulmonary lesions. The percentage of vaccinated calves that shed virus in nasal secretions was significantly lower than the percentage of control calves that did, and peak viral titer was lower for vaccinated than for control calves. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that the inactivated BRSV vaccine provided clinical protection from experimental infection with virulent virus and decreased the severity of pulmonary lesions. Efficacy was similar to that reported for modified-live BRSV vaccines.     

Antibody response of calves after intranasal inoculation with parainfluenza-3 virus and resistance of inoculated calves to experimental homologous viral infection

The immunologic response of colostrum-deprived calves to parainfluenza-3 (PI-3) virus given by intranasal inoculation was studied. Inoculation of calves with 3.2 x 10(6) median cell culture infective doses (CCID50) of either virulent (SF-4) virus or a modified strain of PI-3 virus, or with 2.0 x 10(8) CCID50 of SF-4 virus, stimulated development of both serum antibody and nasal secretion (NS) antibody. However, NA antibody decreased in all calves between the 16th and 42nd postinoculation days and was present only at low or moderately low concentrations on the 126th day, when the immunity of the calves was challenged. Generally, calves that were inoculated with 3.2 x 10(6) CCID50 of SF-4 virus developed slightly higher concentrations of serum and NS antibodies than did calves inoculated with modified virus. Calves that were inoculated with 2.0 x 10(8) or 3.2 x 10(6) CCID 50 of SF-4 virus developed comparable concentrations of serum antibody, but large doses of SF-4 virus were less effective than smaller doses of the same virus in stimulating the development of NS antibody. Reinoculation of 3 calves with modified PI-3 virus resulted in a demonstrable increase in serum antibody in 2 calves and an increase and subsequent decrease in NS antibody in all calves. Challenge exposure of inoculated calves to aerosols of SF-4 virus failed to cause clinical signs of disease, and the challenge virus was not isolated from the nasal passages.     

Characterization and identification of a bovine respiratory syncytial virus isolated from young calves.

Two identical viruses designated 371 and 375 were recovered from nasal secretions of 2 of 7 calves in a beef cow-calf herd in which calves (45 to 105 days of age) had signs of acute respiratory tract disease. The cytopathic, morphologic and physico-chemical characteristics of the isolates were those of bovine respiratory syncytial virus. Although a humoral antibody response to bovine respiratory syncytial virus was not observed, it was concluded that this virus probably had a part in the respiratory tract disease in these calves.     

Efficacy of a saponin-adjuvanted inactivated respiratory syncytial virus vaccine in calves

The objective of this study was to determine whether a commercially available, saponin-adjuvanted, inactivated bovine respiratory syncytial virus (BRSV) vaccine would protect calves from experimental infection with virulent BRSV. This was a randomized controlled trial comprising 14, 8- to 9-week-old calves seronegative for BRSV Group 1 calves (n = 8) were not vaccinated and group 2 calves (n = 6) were vaccinated on days 0 and 19 with an inactivated BRSV vaccine. All calves were challenged with virulent BRSV on day 46. Clinical signs, arterial PO2, and immune responses were monitored after challenge. Calves were euthanatized on day 54 (8 d after challenge) and lungs were examined for lesions. Vaccination elicited increases in BRSV-specific immunoglobulin (Ig) G and virus neutralizing antibody titers. Challenge with BRSV resulted in severe respiratory tract disease and extensive pulmonary lesions in control calves, but no signs of clinical disease and minimal or no pulmonary lesions in vaccinated calves. Arterial blood oxygen values on day 53 (7 d after challenge) in control calves were significantly lower than those in vaccinated calves, which remained within normal limits. Control calves shed BRSV for several days after challenge, whereas BRSV was not detected on deep nasal swabs from vaccinated calves. In summary, the results indicated that this inactivated BRSV vaccine provided clinical protection from experimental infection with virulent virus 27 d after vaccination and significantly decreased the prevalence and severity of pulmonary lesions. Efficacy was similar to that reported for other commercial inactivated and modified-live BRSV vaccines.     

Immunogenicity, pathogenicity, and transmissibility of a recombinant vaccinia virus in calves

Experiments concerned with the immunogenicity, pathogenicity, and transmissibility of a recombinant vaccinia:Sindbis virus were conducted. The WR strain of the recombinant vaccinia:Sindis virus was found to be infective for calves and mildly pathogenic, resulting in local tissue reaction. It was not transmissible to other calves. Also, it was found to be immunogenic when inoculated intradermally into calves, and antibody was produced against the parent vector virus (vaccinia) and the Sindbis antigen. Recombinant virus given IV to calves induced no detectable clinical signs, nor did the calves develop neutralizing antibodies. Furthermore, second-passage lesion material containing up to 10(7) tissue culture infective doses of the recombinant virus failed to induce development of lesions or illness in intradermally inoculated calves, and virus could not be recovered from the inoculation sites. In this series of experiments, this vaccinia recombinant given intradermally was immunogenic, mildly pathogenic at the local injection site only, and was not transmissible to contact animals, thus demonstrating the potential efficacy and safety of the WR strain of vaccinia virus when used as a live vector system in cattle.     

Experimental respiratory syncytial virus pneumonia in young calves: microbiologic and immunofluorescent findings

Young calves were inoculated with respiratory syncytial virus (RSV) intranasally or by a combined intranasal and intratracheal route and were killed between postinoculation (initial) days (PID) 1 and 14. Viral antigens were detected by immunofluorescence in nasopharyngeal cells from calves killed between PID 2 and 10. Evidence of infection of the trachea and lungs with RSV was obtained by immunofluorescence and virus isolation in calves inoculated by the combined route, but not in calves inoculated intranasally. Within the lungs, RSV antigens were observed in epithelial cells of bronchioli and alveoli. The only virus detected in inoculated calves was RSV. With the exception of 1 calf, bacteria or mycoplasmas were not isolated from the lower respiratory tracts of inoculated calves. Antibody to RSV was not detected in calves killed up to PID 5, but 4 of 5 colostrum-deprived calves killed between PID 10 and 13 had antibodies to RSV. Preexisting, maternally derived antibody to RSV did not protect the calves from infection. Seemingly, the clinical signs of pneumonia and pathologic lesions observed in inoculated calves were caused by RSV infection.     

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.     

Immunofluorescent Studies of Bovine Para-Influenza 3 Virus II. Experimentally Infected Calves

Fluorescent antibody (FA) studies of tissues from three colostrum deprived calves inoculated intranasally with the SF-4 strain of bovine para-influenza 3 (PI-3) virus indicated that these calves developed a mild upper respiratory infection but infected cells were not identified in the lower respiratory tract. Three other calves inoculated intranasally and intratracheally with PI-3 virus developed more severe clinical signs of infection and virus was identified, by FA techniques, in the upper and lower respiratory tract of all three calves and in the spleen of one calf. PI-3 virus was detected in smears of nasal epithelium from five of six calves at some time during the observation period.     

Protection against bovine respiratory syncytial virus challenge following a single dose of vaccine in young calves with maternal antibody

Twenty-one young calves with maternally derived antibody to bovine respiratory syncytial virus (BRSV) were divided into three groups of seven, each group balanced for BRSV antibody titre. The calves had no evidence of previous exposure to BRSV. The calves in one group were given a single dose of a monovalent modified live BRSV vaccine; the calves in the second group were given a single dose of an inactivated combined BRSV, parainfluenza virus type 3, Mannheimia haemolytica vaccine and the calves in the third group were left as unvaccinated controls. Three weeks after the single doses of vaccine, all the calves were challenged with BRSV. The clinical signs of disease were mild, and virus excretion was limited to two calves in the group given the inactivated vaccine, compared with six in the negative controls (P = 0.05) and five in the group given the live vaccine. The mean virus excretion titres after the challenge were not significantly different between the groups. There was little seroconversion before the challenge, but six of the seven calves in the group given the inactivated vaccine showed significant seroconversion within two weeks after the challenge, compared with only one calf in each of the other two groups (P = 0.015).     

The effect of dexamethasone-induced immunosuppression on the development of faecal antibody and recovery from and resistance to rotavirus infection.

Rotavirus-naive and rotavirus-immune gnotobiotic calves were treated with high doses of dexamethasone (DX) to suppress the immune system. Calves were then infected with a virulent rotavirus inoculum, J-160, to investigate the role of immune responses both in recovery from primary rotavirus infection and in resistance to secondary rotavirus infection. Treatment of calves with DX markedly suppressed in vitro responsiveness of peripheral blood lymphocytes to mitogens within 48 h of the start of DX treatment. Suppression was similar in rotavirus-naive and rotavirus-immune calves. In contrast, the effect of DX treatment on specific antibody responses differed depending on when DX treatment started in relation to rotavirus infection. When DX treatment commenced prior to primary rotavirus infection both systemic and local specific antibody responses were inhibited. These calves, in which mitogen and antibody responses were suppressed, exhibited greater clinical signs than did control calves after infection with virulent rotavirus, but virus excretion was affected in only one of the two calves. When DX treatment was started after primary rotavirus infection but before secondary infection, systemic and local antibody responses to the primary infection and to the challenge infection were not affected. These calves resisted challenge with virulent virus as did DX-untreated rotavirus-immune calves, even though mitogen responses were suppressed. We conclude that in a primary rotavirus infection, virus excretion ceased when both antibody and mitogen responses were suppressed. Resistance to secondary rotavirus infection occurred when mitogen responsiveness was suppressed, but when antibody levels were normal. Thus, no evidence was obtained that fully functional cell-mediated immune mechanisms are essential for resistance to rotavirus infection. Evidence was provided for the ability of parenteral treatment with DX to suppress mucosal as well as systemic antibody responses.     

Exposure of calves to aerosols of parainfluenza-3 virus and Pasteurella haemolytica.

The present study was undertaken to investigate whether sequential exposure to aerosols of parainfluenza-3 virus followed by Pasteurella haemolytica, or P. haemolytica followed by parainfluenza-3 virus, could lead to the production of pulmonary lesions in conventionally-raised calves. Twenty male calves with low serum antibody titres to both organisms were placed in five equal groups. Synergism of parainfluenza-3 virus and P. haemolytica was not demonstrated in any of the sequentially infected groups and pulmonary lesions were mild in all challenged calves. Clinical signs of disease were not present after exposure to parainfluenza-3 virus although the virus was repeatedly isolated from nasal secretions of all inoculated calves. Exposure to P. haemolytica produced a transient response which consisted of increased rectal temperatures and respiratory rates, with a mild neutrophilic leukocytosis and a mild left shift present six hours postinoculation and returning to normal within 24 hours. Results from this study suggest, although do not confirm, that reduced pulmonary clearance of inhaled P. haemolytica in parainfluenza-3 virus infected calves does not necessarily lead to production of severe pulmonary lesions and that previous exposure to aerosols of P. haemolytica may not enhance secondary parainfluenza-3 virus infection.     

The estimation of duration of maternally-derived antibodies against Akabane,Aino, and Chuzan virus in calves by the receiver operating characteristic analysis

The duration of maternally-derived antibodies against three arboviruses was investigated in calves, using the results of arbovirus serosurveillance performed in Kagoshima Prefecture during 2002–2016. The duration of maternally-derived antibodies against Akabane virus (AKAV), Aino virus (AINOV), and Chuzan virus (CHUV) was estimated to be 178 (sensitivity: 0.769, specificity: 0.730), 156 (sensitivity: 0.806, specificity: 0.791), and 156 days of age (sensitivity: 0.845, specificity: 0.814), by receiver operating characteristic analysis. The duration of maternally-derived antibodies against AKAV, AINOV, and CHUV differed 7–14, 22–28, and 20–31 days in the same calf types between the regions far from each other although it was similar between the adjacent regions. The dairy calves showed 6–29 days longer duration than the beef calves rearing in a similar region.