Suppressed lymphocyte blastogenic responses and enhanced in vitro growth of infectious bovine rhinotracheitis virus in stressed feeder calves

Hereford steers were stressed on a large-animal treadmill operating at speeds of 1.8 to 2.2 m/s. Blood samples were collected from indwelling jugular catheters before, during, and after exercise. Peripheral blood lymphocytes from stressed calves at 5 and 30 minutes after exercise had less (P less than 0.01) mitogen-induced blastogenic responses when compared to pre- or 60-minute postexercise values. Serum from stressed calves incorporated into lymphocyte cultures from nonstressed steers resulted in less (P less than 0.01) lymphocyte blastogenic responses. Infectious bovine rhinotracheitis viral growth in bovine kidney cell cultures was enhanced 4-fold when cultured with serum from stressed calves. These data indicate that acute physical exertion may cause physiologic alterations in calves that modulate cellular immunity and viral replication.     

Comparative serological response in calves to eight commercial vaccines against infectious bovine rhinotracheitis, parainfluenza-3, bovine respiratory syncytial, and bovine viral diarrhea viruses

A field trial was conducted to compare the serological responses in calves to eight commercial vaccines against infectious bovine rhinotracheitis virus (IBRV), parainfluenza-3 virus (PI3V), bovine respiratory syncytial virus (BRSV), and/or bovine viral diarrhea virus (BVDV). Calves given IBRV, P13V, BRSV, and BVDV vaccines had significantly higher antibodies to these viruses than unvaccinated controls; however, serological responses to killed BVDV vaccines were low. Calves with preexisting antibodies to IBRV, PI3V, BRSV, and the Singer strain of BVDV had lower seroconversion rates following vaccination than calves that were seronegative initially.

Serological responses in calves to IBRV, PI3V, BRSV, and BVDV differed among various commercial vaccines. Antibody titers to IBRV were higher in calves vaccinated with modified-live IBRV vaccines than in those vaccinated with killed IBRV vaccines. Following double vaccination with modified-live IBRV and PI3V vaccines, seroconversion rates and antibody titers to IBRV and PI3V were higher in calves vaccinated intramuscularly than in those vaccinated intranasally. Calves given Cattlemaster 4 had significantly higher titers to BRSV and PI3V, and lower titers to BVDV, than calves given Cattlemaster 3, suggesting that the addition of BRSV to Cattlemaster 4 caused some interaction among antigens.

     

The association between serological titers in infectious bovine rhinotracheitis virus, bovine virus diarrhea virus, parainfluenza-3 virus, respiratory syncytial virus and treatment for respiratory disease in Ontario feedlot calves.

A seroepidemiological study of the association between antibody titers to infectious bovine rhinotracheitis, parainfluenza-3, bovine virus diarrhea and bovine respiratory syncytial viruses, and treatment for bovine respiratory disease was conducted. A total of 322 calves from five different groups were bled on arrival, then one month later all cases (cattle treated for bovine respiratory disease) were rebled together with an equal number of controls (cattle not treated for any disease). Titers to these viruses varied significantly from group to group. Based on seroconversion, infectious bovine rhinotracheitis virus was active in 4.4%, bovine virus diarrhea virus in 24%, parainfluenza-3 virus in 69.5% and bovine respiratory syncytial virus in 71.3% of the cattle. Cattle with low titers to infectious bovine rhinotracheitis and/or bovine respiratory syncytial viruses on arrival, were at increased risk of subsequent treatment for bovine respiratory disease. Treated cattle also had significantly greater increases to parainfluenza-3 and/or bovine virus diarrhea viruses than control calves. Treatment rates varied considerably from group to group and were not strongly correlated with weight gain in the postarrival period.     

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)     

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.     

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.     

Diagnosis of infectious bovine rhinotracheitis by direct immunofluorescence

Summary Clinical signs, virus excretion and immunofluorescence in nasal smears were studied in nine susceptible steers during a two week period, following intranasal expo-sure with IBR-virus. All animals responded with fever (ay. 3.9 days) and nasal discharge. IBR-virus was isolated from nasal swabs from 1 to 11 days after exposure (ay. 10 days), whereas fluorescence in nasal smears was observed from the second till the seventh day after infection (ay. 5.5 days). Fluorescence was most distinct 3 to 5 days after infection, which coincided with the period of fever and a serous nasal discharge. Smears from animals with a mucopurulent or slightly haemorrhagic nasal discharge were nearly always negative. For a reliable diagnosis on live animals by immunofluorescence, it is necessary to take nasal smears from several healthy looking animals with fever and a slight, preferably serous discharge. Air dried smears should be fixed in acetone within 24 hours. Seven yearlings were autopsied 3 to 11 days after intranasal exposure and subjected to a detailed investigation by the cryostat-immunofluorescence technique (IFT). The tonsils of all animals were positive, followed in declining frequency by the larynx, namharynx, nasal mucosa, and pharyngeal mucosa. Besides the organs already mentioned, fluorescence was often observed in the lungs and tracheal mucosa of animals that had suffered a fatal infection of IBR in the field. The tonsils should be regarded as the organ of choice. Fluorescent foci were localized in the epithelial lining of the tonsillar crypts and in the surface epithelium of the mucosae. The direct IFT on nasal smears of suspected animals and on cryostat sections of tissues collected at autopsy offers veterinary laboratories with no facilities for tissue culture a possibility of a rapid and reliable diagnosis of IBR infections.     

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.     

A review of infectious bovine rhinotracheitis, shipping fever pneumonia and viral-bacterial synergism in respiratory disease of cattle.

Unanswered questions on the etiology and prevention of shipping fever pneumonia have allowed this disease to remain one of the most costly to the North American cattle industry. Research in this area has indirected that while Pasteurella haemolytica and, to a lesser extent, P. multocida are involved in most cases, they seem to require additional factors to help initiate the disease process. Bovine herpes virus 1 has been shown experimentally to be one such factor. This review examines in some detail the topics of infectious bovine rhinotracheitis, shipping fever, and viral-bacterial interactions in the production of respiratory disease in various species. It deals with history, definitions, etiologies, clinical signs and lesions, and considers exposure levels, transmission and various pathogenetic mechanisms that are postulated or known to occur.     

Diagnosis of infectious bovine rhinotracheitis by direct immunofluorescence

Summary

Clinical signs, virus excretion and immunofluorescence in nasal smears were studied in nine susceptible steers during a two week period, following intranasal expo‐sure with IBR‐virus. All animals responded with fever (ay. 3.9 days) and nasal discharge. IBR‐virus was isolated from nasal swabs from 1 to 11 days after exposure (ay. 10 days), whereas fluorescence in nasal smears was observed from the second till the seventh day after infection (ay. 5.5 days).

Fluorescence was most distinct 3 to 5 days after infection, which coincided with the period of fever and a serous nasal discharge. Smears from animals with a mucopurulent or slightly haemorrhagic nasal discharge were nearly always negative. For a reliable diagnosis on live animals by immunofluorescence, it is necessary to take nasal smears from several healthy looking animals with fever and a slight, preferably serous discharge. Air dried smears should be fixed in acetone within 24 hours. Seven yearlings were autopsied 3 to 11 days after intranasal exposure and subjected to a detailed investigation by the cryostat‐immunofluorescence technique (IFT). The tonsils of all animals were positive, followed in declining frequency by the larynx, namharynx, nasal mucosa, and pharyngeal mucosa. Besides the organs already mentioned, fluorescence was often observed in the lungs and tracheal mucosa of animals that had suffered a fatal infection of IBR in the field. The tonsils should be regarded as the organ of choice. Fluorescent foci were localized in the epithelial lining of the tonsillar crypts and in the surface epithelium of the mucosae. The direct IFT on nasal smears of suspected animals and on cryostat sections of tissues collected at autopsy offers veterinary laboratories with no facilities for tissue culture a possibility of a rapid and reliable diagnosis of IBR infections.