Influence of immunomodulatory agents on bovine humoral and cellular immune responses to parenteral inoculation with bovine rotavirus vaccines

Sodium diethyldithiocarbamate (DTC), mycobacterium cell wall extract (MCWE, Regressin), killed Corynebacterium parvum (C. parvum, Immunoregulin) and muramyldipeptide (MDP) were each combined with purified, live bovine rotavirus and inoculated into 3 month-old Holstein-Friesian calves in order to examine their ability to potentiate specific humoral and cellular immune responses. The vaccinated calves were boosted twice at 3 and 6 weeks after initial vaccine inoculation. The rotavirus was administered intramuscularly either in an aqueous suspension or in a water-in-oil (WIO) emulsion, prepared with incomplete Freund's adjuvant (IFA). DTC and C. parvum were given by the intravenous route, while MCWE and MDP were incorporated directly in the rotavirus suspension. Two groups of calves were also vaccinated either with rotavirus and IFA or with rotavirus emulsified in mineral oil and a mannide oleate compound (MOC, Montanide 888). A control group of calves was given phosphate-buffered saline (PBS) solution emulsified with IFA. The different vaccine preparations were then compared by studying the kinetics of serum rotavirus-neutralizing antibody production and of proliferative response by blood lymphocytes following in vitro stimulation with bovine rotavirus. The results showed that: (1) the bovine rotavirus should be incorporated in a WIO emulsion in order to induce a cell-mediated immune response as detected by the rotavirus-specific in vitro stimulation test with blood lymphocytes, and to produce higher neutralizing antibody titers in the serum; (2) the vaccines prepared with the mineral oil-MOC complex or IFA both induced comparable levels of humoral and cellular immune responses. The use of mineral oil and MOC as adjuvant may be preferred to IFA, because of the facility of preparing the vaccine and of the low viscosity of the resulting WIO emulsion: (3) the addition of MDP to the WIO emulsion prepared with IFA resulted in a higher cell-mediated immune response as determined by the in vitro blood lymphocyte transformation index specific for bovine rotavirus.     

Immune response of pregnant heifers and cows to bovine rotavirus inoculation and passive protection to rotavirus infection in newborn calves fed colostral antibodies or colostral lymphocytes

The efficacy of an adjuvanted bovine rotavirus vaccine in pregnant cattle (15 heifers and 2 cows) was studied. Each of 4 animals was inoculated IM at 8, 5, and 2 weeks before parturition with a water-in-oil emulsion containing live purified bovine rotavirus, mineral oil, and a mannide oleate compound. Four other animals were treated identically, except that muramyl dipeptide was added to the virus preparation. Five additional animals were inoculated orally at the same time intervals with adjuvant-free viral suspension, and 4 other pregnant animals inoculated only with buffer served as uninoculated controls. Kinetic studies of the specific immune responses were determined by quantification of the rotavirus-neutralizing antibodies and by a rotavirus lymphocyte stimulation test in vitro. Results showed that only the emulsions induced marked enhancement of rotavirus antibody titers in the serum, colostrum, and milk of inoculated cows. Colostral and milk lymphocytes isolated from these cows had a positive in vitro proliferative response to rotavirus stimulation, which lasted at least 21 days after parturition. The values of the stimulation index obtained with the colostral/milk lymphocytes were higher than those of the blood lymphocytes, reflecting increased lymphocyte activity in the colostrum/milk. However, addition of muramyl dipeptide to the emulsion preparation did not exert any potentiating effect on the immune response to rotavirus. Calves fed for the first 5 days after birth with a rotavirus-immune cell-free colostrum supplement were protected from a rotavirus challenge exposure on the third day after birth. Virus was not detectable in their feces.(ABSTRACT TRUNCATED AT 250 WORDS)     

Development of nasal, fecal and serum isotype-specific antibodies in calves challenged with bovine coronavirus or rotavirus

Unsuckled specific pathogen free calves were inoculated at 3-4 weeks of age, either intranasally (IN) or orally (O) with bovine coronavirus or O plus IN (O/IN) or O with bovine rotavirus. Shedding of virus in nasal or fecal samples, and virus-infected nasal epithelial cells were detected using immunofluorescent staining (IF), ELISA or immune electron microscopy (IEM). Isotype-specific antibody titers in sera, nasal and fecal samples were determined by ELISA. Calves inoculated with coronavirus shed virus in feces and virus was detected in nasal epithelial cells. Nasal shedding persisted longer in IN-inoculated calves than in O-inoculated calves and longer than fecal shedding in both IN and O-inoculated calves. Diarrhea occurred in all calves, but there were no signs of respiratory disease. Calves inoculated with rotavirus had similar patterns of diarrhea and fecal shedding, but generally of shorter duration than in coronavirus-inoculated calves. No nasal shedding of rotavirus was detected. Peak IgM antibody responses, in most calves, were detected in fecal and nasal speciments at 7-10 days post-exposure (DPE), preceeding peak IgA responses which occurred at 10-14 DPE. The nasal antibody responses occurred in all virus-inoculated calves even in the absence of nasal shedding of virus in rotavirus-inoculated calves. Calves inoculated with coronavirus had higher titers of IgM and IgA antibodies in fecal and nasal samples than rotavirus-inoculated calves. In most inoculated calves, maximal titers of IgM or IgA antibodies correlated with the cessation of fecal or nasal virus shedding. A similar sequence of appearance of IgM and IgA antibodies occurred in serum, but IgA antibodies persisted for a shorter period than in fecal or nasal samples. Serum IgG1 antibody responses generally preceeded IgG2 responses and were predominant in most calves after 14-21 DPE.     

The bovine lymphoid system: II. Derivation and partial characterlzation of monoclonal antibodies against bovine peripheral blood lymphocytes

We have raised monoclonal antibodies to produce reagents specific for bovine lymphocyte subpopulations. Spleen cells from mice immunized with bovine peripheral blood lymphocytes were fused with X63-Ag8 myeloma cells and eleven myeloma-hybrids which secreted antibody specific for bovine lymphocytes were doubly cloned. Five of the hybrids secreted antibodies which bound to the majority of bovine lymphocytes. Two of these antibodies were specific for polymorphic antigens. One antibody bound to B lymphocytes and serum IgM molecules. The remaining five bound to subpopulations of lymphocytes. Four monoclonal antibodies bound only to bovine cells while six also bound to lymphocytes from other bovidae. None bound to human lymphocytes. We discuss the difficulty of correlating the specificities of monoclonal antibodies to functional lymphocyte subpopulations in outbred animals where few other defined markers are available.     

Intestinal antibody response after vaccination and infection with rotavirus of calves fed colostrum with or without rotavirus antibody

The intestinal and systemic antibody response of calves vaccinated and/or challenged with rotavirus was studied employing isotype-specific ELISAs for the detection of IgG1, IgG2, IgM and IgA antibodies to rotavirus. Monoclonal antibodies to bovine immunoglobulin isotypes of proven specificity were used as conjugated or catching antibody. Five days after oral inoculation (dpi) of a 5-day-old gnotobiotic calf with rotavirus, IgM rotavirus antibodies were excreted in faeces, followed 5 days later by IgA rotavirus antibodies. The increase in IgM rotavirus antibody titre coincided with the inability to detect further rotavirus excretion. Faeces IgM and IgA rotavirus antibody titres fell to low levels within 3 weeks post infection. IgG1 and IgG2 rotavirus antibodies were not detected in faecal samples. In serum, antibodies to rotavirus of all four isotypes were detected, starting with IgM at 5 dpi. Two SPF-calves, which were fed colostrum free of rotavirus antibodies, were vaccinated with a modified live rotavirus vaccine and challenged with virulent rotavirus 6 days later. Upon vaccination, the calves showed an antibody response similar to the response of the infected gnotobiotic calf. Intestinal IgM rotavirus antibodies were excreted before or on the day of challenge and appeared to be associated with protection against challenge infection with virulent virus and rotavirus-induced diarrhoea. In 3 control calves, which were challenged only, the antibody patterns also resembled that of the gnotobiotic calf and again the appearance of IgM rotavirus antibodies coincided with the end of the rotavirus detection period. Two other groups of 3 SPF-calves were treated similarly, but the calves were fed colostrum with rotavirus antibodies during the first 48 h of life. These calves excreted passively acquired IgG1 and IgG2 rotavirus antibodies in their faeces from 2 to 6 days after birth. After vaccination, no IgM or IgA antibody activity in serum or faeces was detectable. Upon challenge, all calves developed diarrhoea and excreted rotavirus. Seven to 10 days after challenge low levels of IgM rotavirus antibody were detected for a short period. These data indicate that the intestinal antibody response of young calves to an enteric viral infection is associated with the excretion of IgM antibodies, immediately followed by IgA antibodies. This response is absent or diminished in calves with passively acquired specific antibodies which may explain the failure to induce a protective intestinal immune response by oral vaccination with modified live rotavirus of calves fed colostrum containing rotavirus antibodies.     

Preliminary studies with a live streptomycin-dependent Pasteurella multocida and Pasteurella haemolytica vaccine for the prevention of bovine pneumonic pasteurellosis.

Twelve Pasteurella-free Holstein-Friesian calves were used in a study to test the efficacy of a live streptomycin-dependent Pasteurella multocida A:3 and streptomycin-dependent Pasteurella haemolytica A1 vaccine. The calves were inoculated intramuscularly twice at 14-day intervals with either the streptomycin-dependent vaccine, containing 1 X 10(6) colony forming units/mL P. multocida and 4 X 10(8) colony forming units/mL P. haemolytica, commercial bacterin, or phosphate buffered saline. Two weeks following the second vaccination, all calves were challenged by intranasal inoculation of 10(8) TCID50/4.0 mL infectious bovine rhinotracheitis virus followed three days later by intratracheal injection with 2.3 X 10(7) colony forming units/mL of a 16 hour culture of P. multocida A:3 and 2.6 X 10(8) colony forming units/mL of an 8 hour culture of P. haemolytica A1. Seven days after challenge with Pasteurella, calves were killed for collection of tissues at necropsy. Each calf was given a score based on macroscopic and microscopic lesions. The scores for the calves receiving live vaccines were significantly lower (p less than 0.025) than those for the controls. Also, the calves receiving live vaccines had a significant (p less than 0.05) increase in the level of serum antibody to P. haemolytica. The results of this preliminary study showed that the streptomycin-dependent vaccine offered better protection than the commercial bacterin against a virulent homologous challenge.     

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.     

Prevention of bovine respiratory syncytial virus infection and clinical disease by vaccination

A double blind field trial was carried out with a live attenuated bovine respiratory syncytial virus vaccine. The trial involved 530 calves, two to 10 months old, on 27 dairy farms, where respiratory problems due to bovine respiratory syncytial virus infections had been observed during the preceding year. In 17 herds either all calves were vaccinated (nine groups) or all calves received a placebo (eight groups). In 10 herds half the number of calves were vaccinated and the other half kept as non-vaccinated controls. Calves were vaccinated intramuscularly twice with an interval of four to five weeks. These groups were under regular clinical observation and animals were tested periodically for antibodies to bovine respiratory syncytial virus and parainfluenza type 3 virus. Serological examination indicated that no bovine respiratory syncytial virus infection had occurred prior to the first vaccination in August. Vaccination did not cause adverse reactions. Low concentrations of neutralising and complement fixing antibodies were induced by vaccination and a sharp increase of antibody titres was observed after natural infection of vaccinated animals. Infections with bovine respiratory syncytial virus occurred in six out of eight non-vaccinated groups, in nine out of 10 partly vaccinated groups and in only two out of nine completely vaccinated groups. Virus infection in completely vaccinated groups was significantly reduced compared with partly vaccinated and non-vaccinated groups. The incidence of bovine respiratory syncytial virus lower respiratory disease was significantly reduced in completely vaccinated groups compared to non-vaccinated groups. Generally only mild signs of upper respiratory disease were present in completely vaccinated groups after bovine respiratory syncytial virus infection.(ABSTRACT TRUNCATED AT 250 WORDS)     

Prevalence of antibodies to four bovine rotavirus strains in different age groups of cattle

Neutralizing antibody titers to four bovine rotavirus strains, representing three serotypes, were measured in 160 sera from cattle of different age groups. Age-specific seroprevalence analysis revealed serotype 6, represented by bovine rotavirus (BRV) NCDV, as the predominant rotavirus serotype infecting German cattle and serotype 10, represented by BRV V1005, as the least prominent. Infections with serotype 8, represented by BRV 678, occurred with intermediate frequency. Antibodies of young calves distinguished between NCDV and UK virus, two serotype 6 BRV strains differing in VP4 antigen.     

Prolonged excretion and failure of cross-protection between distinct serotypes of bovine rotavirus

Four newborn calves were experimentally infected with two distinct serotypes of bovine rotavirus (BRV-1 and BRV-2). Initially, three colostrum-deprived calves were inoculated orally with either BRV-1 or BRV-2; all developed severe diarrhea and produced serotype-specific neutralizing antibodies. Fecal virus was first demonstrated by immunofluorescence the day after inoculation. The virus titers reached a maximum of 10(5.2)-10(6.6) fluorescent focus forming units g-1 of feces 2-5 days after inoculation and then decreased. Fecal virus was detected in low titers beyond 28 days after inoculation despite the development of serum neutralizing antibodies. One calf, which had acquired specific active immunity against BRV-1 following oral infection, was further infected orally with BRV-2 4 weeks later. The calf again manifested diarrhea, excreted BRV-2 and showed an increase in serum neutralizing antibody against BRV-2. These results indicated that calves infected with either BRV-1 or BRV-2 do not have cross-protection to infection with heterologous BRV, and that recurrence of the disease can occur. The possible mechanisms of the persistence of BRV in calves and its role in the epidemiology of this infection are discussed.     

In vitro and in vivo immune responses in neonatally thymectomized holstein-friesian calves exposed to bovine viral diarrhea virus

Neonatally thymectomized and normal Holstein-Friesian calves were exposed to bovine viral diarrhea virus and challenged 22 days later. Baseline values in non-specific mitogen induced lymphocyte blastogenesis and serologic responses to tetanus toxoid and Brucella abortus strain 19 were established in neonatally thymectomized and normal calves.Neither viral recovery nor protective antibody production followed the very low level primary exposure to bovine viral diarrhea virus. The expected clinical response to an appropriate challenge inoculum did not occur, however, suggesting an immune response to bovine viral diarrhea virus had been initiated by the primary exposure. Five of eight calves developed protective serum levels of bovine viral diarrhea antibody. This may represent an example of immunologic priming. Exposure to low levels of bovine viral diarrhea virus also has potential implications in the pathogenesis of chronic bovine viral diarrhea wherein low level exposure may interfere with the development of protective levels of bovine viral diarrhea antibody as was observed in three calves.Circulating lymphocyte concentrations and results of non-specific mitogen stimulation of lymphocytes revealed a reduced phytohemagglutinin response in conjunction with a slightly increased response to bacterial lipopolysaccharide and pokeweed mitogen in the presence of moderate lymphopenia. The capacity of lymphocytes to respond to phytohemagglutinin was unchanged but an increased total response, as occurred in control thymectomized and intact calves, did not occur.The response to tetanus toxoid, a thymus-independent antigen, was increased following exposure to bovine viral diarrhea virus, perhaps reflecting an alteration in thymic-independent regulation. The lack of a differential response to Brucella abortus strain 19 implied competence in thymus-dependent helper cells.     

Studies on cross protection induced in calves by rotaviruses of calves, children and foals.

Inoculation at birth with a live attenuated strain of a bovine rotavirus isolated in the USA (scourvax-reo) induced protection in five gnotobiotic calves seven to 21 days later against a UK isolate of pathogenic bovine rotavirus. However, no protection was induced in three calves challenged three to five days after vaccination. There was a close antigenic relationship demonstrated between the two bovine rotavirus isolates. In contrast only one of three gnotobiotic calves inoculated with foal rotavirus, and one of three with human rotavirus, were protected against bovine rotavirus challenge. Protection in these two calves correlated with high heterologous immunofluorescent antibody titre (320 or greater), although the neutralising antibody titres was less than 20.     

Establishment of an attenuated strain of bovine respiratory syncytial virus for live virus vaccine

To develop a live virus vaccine for the prevention of bovine respiratory syncytial (BRS) virus infection in calves, an attempt was made to produce an attenuated virus. The RS-52 strain of BRS virus, isolated from the nasal secretions of a naturally infected calf, was subjected to serial passages in adult hamster lung established (HAL) cells at 30 degrees C and the attenuated rs-52 strain as a live virus vaccine was established. The rs-52 strain multiplied better at 30 degrees C than at 34 or 37 degrees C in HAL cells. The differences in the highest virus titers of this strain between the culture temperature of 30 degrees C and that of 34 or 37 degrees C were more than 2.25 log TCID50. Colostrum-deprived newborn calves and 2 approximately 4 months old calves inoculated with the rs-52 strain manifested no abnormal clinical sings at all. However, all inoculated calves produced serum neutralization antibody. When the colostrum-deprived newborn calves immunized with the rs-52 strain were challenged with the virulent NMK7 strain of BRS virus, they exhibited no pyrexia or other abnormal clinical signs at all. An attempt was made to recover the virus from nasal secretions of these calves, but in vain. On the other hand, a nonimmunized control colostrum-deprived newborn calf developed slight fever, mild cough, and slight serous nasal discharge after challenge exposure. The virus was recovered from nasal secretions of this calf. From these results, it was considered that the rs-52 strain could be used as an attenuated live virus vaccine for prevention of BRS virus infection.     

Association of bovine viral diarrhea virus with multiple viral infections in bovine respiratory disease outbreaks

We investigated eleven outbreaks of naturally occurring bovine respiratory diseases in calves and adult animals in the St-Hyacinthe area of Quebec. Specific antibodies to bovine herpesvirus-1, bovine viral diarrhea virus, respiratory syncytial virus, parainfluenza type 3 virus, reovirus type 3, and serotypes 1 to 7 of bovine adenovirus were found in paired sera from diseased animals. Several bovine viruses with respiratory tropism were involved concomitantly in herds during an outbreak of bovine respiratory disease. In addition, concomitant fourfold rises of antibody titers were frequently observed to two or more viral agents in seroconverted calves (61%) or adult animals (38%). Bovine viral diarrhea virus was found to be the most frequent viral agent associated with multiple viral infection in calves only (92%).     

Comparative study of rotavirus strains of bovine and rabbit origin

Newborn calves were susceptible to infection with a rotavirus strain isolated from rabbits and, conversely, rabbits 4–5 weeks of age became ill and some died when inoculated with the rotavirus strain of bovine origin. However, the latter isolate appeared to be more virulent than the rabbit isolate in either calves or rabbits. Moreover, in reciprocal cross protection tests, carried out in calves and in rabbits, the rabbit rotavirus antiserum afforded only weak protection to challenge infection with either the homologous or the heterologous virus. By contrast, the protective level of the bovine rotavirus antiserum was relatively high.     

A new polyvalent vaccine against enteral infections in newborn calves

The most frequent microbial causative agents of massive diarrheas in new-born calves kept on large cattle farms in the CSSR are rotaviruses, coronaviruses and enterotoxigenic strains of E. coli, manifesting themselves as complicated virus-bacterial infections. An inactivated polyvalent adjuvant vaccine has been developed for the prevention and specific prophylaxis of these enteral infections; the vaccine contains bovine rotavirus, bovine coronavirus and three enterotoxigenic serotypes of E. coli with protective antigen K 99. The rotavirus and coronavirus are propagated on the stable cellular line MDBK and inactivated with 0.2% formalin, the Escherichia strains are submersed in the MINCA culture medium during their cultivation and inactivated with 0.5% formalin. The vaccine was prepared as a blend of the same amounts of rotavirus and coronavirus and of such an amount of bacterin so that 1 ml of the vaccine will contain 10(9) bacteria. One part of oil adjuvant was added to five parts of the virus-bacterial blend and the blend was homogenized in the Ultraturax apparatus. The vaccine is to be used for immunization of pregnant cows and heifers; in these animals it induces the production of specific antibodies to all antigens contained in the vaccine. Its immunogenic effects were checked in 32 calves and 38 cows in the herds with the occurrence of diarrheas caused by both enteropathogenic viruses and enterotoxigenic escherichia. It was demonstrated that the inactivation did not influence in either of the viruses the process of inducing the production of specific antibodies, and the antibody response of the calves and heifers after application of 2 ml of complete inactivated vaccine was equally strong as after application of live vaccine containing only rotavirus and coronavirus. The level of the rotavirus antibodies increased on the average 30 times and 200 times, coronavirus antibodies twice and four times. The antibody response to coronavirus was negatively influenced by the relatively high levels of antibodies before vaccination. The antibody response to antigen K 99 was expressive in all cases.     

DNA sequence analysis of glycoprotein G gene of bovine ephemeral fever virus and development of a double oil emulsion vaccine against bovine ephemeral fever

The surface glycoprotein G is considered as the major neutralizing and protective antigen of bovine ephemeral fever virus (BEFV). Comparison of the deduced amino acid sequence of G protein of BEFV isolates during the period 1984-2004 outbreaks in Taiwan showed amino acid substitutions in the neutralizing epitopes. All the isolates differ markedly in the neutralizing epitope at the same amino acid positions compared to the currently available killed vaccine strain (Tn73). Tn88128 strain isolated in 1999 showed the maximum variability of 12 amino acids, 5 amino acid in the neutralization epitope and 7 apart from, respectively. Combinations of both Tn88128 (1999) and commercially available vaccine strain (Tn73) were developed and its safety was evaluated in mice, guinea pigs, calves, and pregnant cows. None of the animals showed any adverse effect or clinical signs. Calves were immunized with commercial vaccine (Tn73) and, combined vaccine (Tn73 and Tn88128), respectively, with adjuvants such as Al-gel and water-in-oil-in-water (w/o/w) oil and PBS alone and challenged with Tn88128 strains. Except PBS administered animals, all the vaccinated animals showed protective immune response. However, animals immunized with combined vaccine plus w/o/w adjuvant elicited stronger neutralization antibodies and long lasting immunity compared to other vaccines.     

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.     

Cytotoxic interactions between bovine parainfluenza type 3 virus and bovine alveolar macrophages

This paper describes an investigation of the cytotoxic activity of bovine alveolar macrophages for parainfluenza type 3 (PI-3) virus-infected target cells, using 51Cr release assays. Alveolar macrophages from uninfected calves were shown to be capable of killing PI-3 virus infected cells without the presence of antibody or complement (antibody-independent cell-mediated cytotoxicity). The level of killing was shown to vary from animal to animal with specific lysis values ranging from <5% to 70%. Presence of PI-3 virus antiserum was shown to inhibit, rather than enhance macrophage cytotoxicity in a dose-dependent manner, suggesting that bovine alveolar macrophages do not always exhibit antibody-dependent lysis in all cases. Following intranasal and intratracheal inoculation of calves with PI-3 virus, the level of cytotoxicity by macrophages lavaged from the lungs of the calves increased substantially, and by Day 5 post inoculation, levels of 95% to 98% specific lysis were recorded. After Day 5, the killing ability decreased rapidly to low levels. Cell-free lavage fluids, collected from PI-3 virus infected and control calves at various times throughout the experiment, were incubated with aliquots of an alveolar macrophage population from an uninfected donor calf, which initially showed a low level of killing, and were subsequently added to PI-3 virus infected target cells. The recorded levels of cytotoxicity, mirrored those which were seen with the initial macrophage effector cells from the infected and control animals, suggesting that macrophage cytotoxicity was largely controlled by extracellular factors.     

Isolation and preliminary characterisation of some bovine enteric viruses

Fifty-eight faeces samples from calves and yearling cattle with diarrhoea were subject to a virus cultural study in monkey kidney cells and bovine embryonic kidney and lung cells. The properties of the 6 viruses isolated indicated that 5 were bovine enteroviruses belonging to 2 biologically different groups, and the remaining virus was probably a rotavirus (reo-like virus).