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)     

新疆阿克苏地区牛传染性鼻气管炎病毒与牛副流感病毒3型感染的检测

为调查阿克苏地区是否存在牛传染性鼻气管炎病毒(IBRV)与牛副流感病毒3型(BPIV-3)的感染,从阿克苏两个规模化奶牛场采集1月龄以内可疑发病犊牛鼻液样品18份,采用双抗体夹心ELISA方法检测两种病毒的抗原,PCR方法检测牛传染性鼻气管炎病毒gD基因,RT-PCR方法检测牛副流感病毒3型的gM基因。结果表明,ELISA方法检测IBRV和BPIV-3的感染率分别为22.22%和0%;PCR方法检测IBRV的感染率为72.22%;RT-PCR检测BPIV-3的感染率为44.44%;同时患有两种病毒的检出率为22.22%。说明在阿克苏地区存在IBRV与BPIV-3的感染,且存在两种病毒的双重感染。     

Survival of infectious bovine rhinotracheitis virus in stored bovine semen

No loss in the titre of infectious bovine rhinotracheitis virus was found during storage in semen at –196°C for 1 year.     

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.     

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.

     

Effects of infectious bovine rhinotracheitis virus infection on bovine airway reactivity.

The response of isolated tracheal and bronchial strips to isoproterenol in vitro was studied in eleven male Jersey calves. Clinical, microbiological and pathological evaluations of the calves were carried out. In calves exposed once or twice to infectious bovine rhinotracheitis virus, the relaxation threshold of the trachealis muscle to isoproterenol was significantly (p less than 0.05) impaired (threshold 5.0 X 10(-7) M, single exposure and 1.0 X 10(-7) M, double exposure), when compared with uninfected controls (threshold 1.0 X 10(-8) M). Single infection significantly impaired tracheal relaxation to isoproterenol doses from 1.0 X 10(-7) to 5.0 X 10(-4) M, and double infection significantly impaired tissue responses at drug doses from 1.0 X 10(-7) to 1 X 10(-4) M. Bronchial relaxation threshold was not significantly inhibited (p less than 0.05) in singly infected or doubly infected animals (threshold 5.0 X 10(-8) M and 1.0 X 10(-8) M, respectively), when compared with uninfected controls (threshold 1.0 X 10(-9) M). Single infection significantly impaired bronchial relaxation at isoproterenol doses from 1.0 X 10(-7) M to 5.0 X 10(-6) M while double infection significantly impaired relaxation only at 5.0 X 10(-7) M. The disruption of normal homeostatic bronchodilatory mechanisms may predispose animals infected with infectious bovine rhinotracheitis virus to secondary bacterial infections due to excessive airway constriction and subsequent compromise of lung defenses.     

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.     

Effects of swab materials on infectious bovine rhinotracheitis virus.

The recovery rates of infectious bovine rhinotracheitis virus from swab materials were compared. The adsorptive and elutive properties of cotton, polyester, and calcium alginate wool were examined by direct exposure of infectious bovine rhinotracheitis virus to swab materials in buffered tissue culture medium. Calcium alginate wool was virucidal; this was apparent after 2 hours' exposure. Cotton and polyester swab materials exhibited little virucidal effects. The addition of wooden applicator sticks with the swab materials reduced viral titers further.     

Demonstration of infectious bovine rhinotracheitis virus antigen in paraffin sections

Nine pregnant heifers were inoculated intravenously with infectious bovine rhinotracheitis virus (IBRV) in the sixth month of pregnancy. Tissues were collected from the fetus of a heifer killed 13 days postinoculation (PI), from fetuses of 6 heifers that aborted 16-27 days PI, and from mummified fetuses of 2 heifers that aborted 53 and 85 days PI, respectively. Control tissues were obtained from the fetus of a non-inoculated heifer that was killed in the seventh month of gestation. Tissues were fixed in 10% formalin, embedded in paraffin, and examined for viral antigen by immunohistochemistry, using biotinylated second antibody and alkaline phosphatase-labeled avidin-biotin complex. Antigen was detected in at least 1 tissue from the fetus of each inoculated heifer. Positive tissues included lung, liver, spleen, kidney, adrenal, and placenta. In several fetuses, antigen was identified in tissues from which virus was not isolated in cell culture. This appeared to occur when tissues had only a few small foci of infection or when tissues were severely autolyzed. The observation of viral antigen in tissues from mummified fetuses indicates that this technique may be useful in diagnostic laboratories to detect IBRV infection in tissues that are not suitable for virus isolation or for examination by the cryostat tissue section-fluorescent antibody technique.