Persistence of antibodies and anamnestic response in calves vaccinated with inactivated infectious bovine rhinotracheitis virus and parainfluenza-3 virus vaccines

Persistence of antibodies in calves vaccinated with 2 types of inactivated infectious bovine rhinotracheitis (IBR) virus and parainfluenza-3 (PI-3) virus vaccines were determined. Calves seronegative for IBR and PI-3 viruses were inoculated with 2 doses of inactivated IBR virus-PI-3 virus vaccines administered 2 weeks apart. Blood samples were obtained from the calves for serum at 2 weeks, 6 months, and 1 year after vaccination. The serums were tested by serum-neutralization tests. Antibody response to the vaccines persisted on a declining scale for 1 year. The anamnestic responses to the vaccines were determined by inoculating the same calves with a booster dose of vaccine 1 year after the original 2 doses were given. Blood samples were obtained from the calves for serum 2 weeks later. The serums were tested by serum-neutralization tests. The single booster dose of vaccine elicited an anamnestic response to both IBR and PI-3 viruses.     

Effects of infection with parainfluenza-3 virus and infectious bovine rhinotracheitis virus on neutrophil functions in calves

Calves were challenge exposed in separate experiments with parainfluenza-3 (PI-3) virus or infectious bovine rhinotracheitis (IBR) virus. Blood neutrophils were assayed for functional activity every other day for at least 3 weeks by random migration, Staphylococcus aureus ingestion, antibody-dependent cell-mediated cytotoxicity, cytochrome-c reduction, iodination, and native chemiluminescence. Exposure to PI-3 virus resulted in a brief febrile response and no other clinical signs. Alterations in total or differential WBC counts were not detected. Chemiluminescence and iodination activities were reduced from activities before exposure. Exposure to IBR virus resulted in mild clinical signs and a febrile response of several days' duration. Total WBC and mononuclear cell counts were reduced. Random migration was reduced, whereas S aureus ingestion was enhanced. We concluded that infection of calves with IBR virus and PI-3 virus might directly or indirectly result in alterations of neutrophil function. The functional alterations apparently are different for each virus. These virus-induced alterations in neutrophil function might predispose calves to secondary bacterial pneumonia.     

Effect of respiratory infections caused by bovine herpesvirus-1 or parainfluenza-3 virus on bovine alveolar macrophage functions

Calves, 90 to 130 days old, were inoculated with bovine herpesvirus-1 (BHV-1) or parainfluenza-3 (PI-3) virus. Pulmonary lavage specimens obtained from calves before virus inoculation contained 98% alveolar macrophages (AM) and 1% neutrophils. Six days after inoculation, the mean percentage of neutrophils in lavage specimens had significantly increased to 7.9 +/- 6.0% in BHV-1-inoculated calves and to 18.3 +/- 9.9% in PI-3 virus-inoculated calves, reflecting viral-induced pulmonary inflammation that was confirmed histologically. Approximately 75% of AM obtained before virus inoculation had Fc surface receptors, and 60% had C3b receptors. Six days after inoculation, the percentage of AM with Fc and C3b receptors was significantly reduced to 69.7 +/- 8.6% and 27.1 +/- 19.8%, respectively, in BHV-1-inoculated calves and to 67.8 +/- 15.4% and 38.8 +/- 23.2%, respectively, in PI-3 virus-inoculated calves. Alveolar macrophages obtained after virus inoculation were significantly impaired in their ability to phagocytize opsonized Staphylococcus epidermidis, but were able to kill ingested bacteria. Alveolar macrophage dysfunctions caused by BHV-1 or PI-3 respiratory infection did not differ appreciably.     

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.     

The pulmonary clearance of Pasteurella haemolytica in calves given Corynebacterium parvum and infected with parainfluenza-3 virus.

Four control calves were aerosolized with parainfluenza-3 and one week later with Pasteurella haemolytica. Three calves were given Corynebacterium parvum at a dose of 15 mg/m2 body surface area, infected with parainfluenza-3 virus one week later, and aerosolized with P. haemolytica two weeks after C. parvum injection. All calves were killed four hours after P. haemolytica exposure and the bacterial retention in the lung was determined. Parainfluenza-3 viral infection did not exert any suppressive effect on pulmonary clearance of P. haemolytica in six out of seven calves used. However, the bacterial colony counts in the lungs of control calves were higher (P less than 0.05) than those in calves given C. parvum. Hence, C. parvum appeared to enhance bacterial clearance. Despite the marked influx of neutrophils into the lungs after the bacterial inoculation, the neutrophil:macrophage ratio in lavage samples was less in calves given C. parvum than in the control calves. The alveolar macrophages in C. parvum treated calves were generally larger but did not differ significantly (P less than 0.05) from those in the controls. There was no significant (P less than 0.05) correlation between the percentages of alveolar macrophages and the bacterial clearance. In calves given C. parvum, bacterial clearance was enhanced in those calves which had larger macrophages.     

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.     

Impaired function of bovine alveolar macrophages infected with parainfluenza-3 virus

Bovine alveolar macrophages (BAM) were harvested from nonsedated cattle, adhered to glass or plastic surfaces, and infected with parainfluenza-3 (PI-3) virus at a multiplicity of infection of 10. Control and PI-3 virus-infected BAM were compared at 24-hour intervals up to 168 hours for their ability to phagocytize antibody-coated sheep erythrocytes (EAC) and latex particles, to kill Staphylococcus epidermidis, and to alter intracellular acid phosphatase concentrations. The effect of antiviral serum on phagocytic functions of virus-infected cells was also evaluated. Compared with noninfected controls, alveolar macrophages infected with PI-3 virus were 15.3% less adherent to the glass or plastic surfaces at postinoculation hour (PIH) 72 and were 64.0% less adherent at PIH 168. Significant differences (P less than 0.05) between the numbers of control and infected BAM phagocytizing EAC were observed at PIH 24 through 72, with final values differing by approximately 50%. Similar changes were observed in the phagocytic efficiencies of individual cells. The PI-3 virus-infected BAM that were exposed to antiserum or to immunoglobulins against PI-3 virus had approximately a 2-fold greater inhibition in EAC phagocytosis than did infected BAM exposed to serum without PI-3 activity. Significant differences in latex particle phagocytosis were not observed between infected and control BAM. Compared with control BAM, the PI-3 virus-infected BAM contained significantly lower concentrations of acid phosphatase from PIH 48 through 96; at PIH 96, acid phosphatase concentrations were 4-fold less in infected than in control BAM.(ABSTRACT TRUNCATED AT 250 WORDS)     

Some characteristics of a natural infection by parainfluenza-3 virus in a group of calves.

Parainfluenza-3 (Pi3) virus infection in a group of 25 calves is described. The virus was isolated from the lungs of four calve at days 6, 7, 13 and 55 after they were housed together at birth. Intracytoplasmic inclusion bodies were seen by light microscopy in bronchial and bronchiolar epithelial cells of two of these calves. Virus infected cells were detected by electron microscopy in three of the four calves. Haemagglutination inhibition antibodies to Pi3 virus were found in the sera of the calves. Despite the virus being present in the group from one week, a significant increase in antibody titre was found in only two animals although all the calves were in contact with each other during the study period. The pulmonary lesions in the four infected calves consisted of a bronchitis and bronchiolitis with infiltration of the walls and lumena of these structures by neutrophils and an adjacent neutrophil infiltration of alveoli some of which were collapsed.     

Studies on the efficacy of intranasal vaccination for the prevention of experimentally induced parainfluenza type 3 virus pneumonia in calves.

The efficacy of intranasal vaccination in preventing or limiting disease of the lower respiratory tract induced by parainfluenza 3 (PI3) virus was evaluated under experimental conditions, using a commercially available live vaccine containing a temperature-sensitive strain of PI3 virus. In a preliminary study four colostrum-deprived calves were vaccinated intranasally at one week and again at two months of age, and two similar calves were given an intranasal placebo. After the second vaccination serum antibodies to PI3 virus were detected in all four vaccinated calves, but not in the control animals. Seventeen days after the second vaccination all six calves were challenged with virulent PI3 virus, and they were killed six days later. The clinical scores and the extent of pulmonary consolidation were reduced in the vaccinated animals; PI3 virus was detected in the upper and lower respiratory tract of the control calves but in none of the vaccinated calves. In a larger scale study with 14 colostrum-fed calves, seven were vaccinated at one week and again at five weeks of age, and seven were given an intranasal placebo. Two weeks after the second vaccination all 14 calves were challenged with virulent PI3 virus. The clinical scores and lung consolidation were significantly reduced in the vaccinated calves in comparison with the controls. Six days after infection, 10 of the 14 calves were killed; PI3 virus was detectable in the nasal secretions of all seven control calves but in only one of the vaccinated animals, and PI3 viral antigen was detected in the lungs of the control calves but not in those of the vaccinated animals. One of the vaccinated calves had developed a severe clinical response after the challenge, but it had only minor lung consolidation when killed.     

Effect of bovine herpesvirus-1 or parainfluenza-3 virus on immune receptor-mediated functions of bovine alveolar macrophages in the presence or absence of virus-specific serum or pulmonary lavage fluids collected after virus infection

The immune receptor-mediated functions of bovine alveolar macrophages (AM) inoculated in vitro with bovine herpesvirus-1 (BHV-1) or parainfluenza-3 (PI-3) virus were tested in the presence or absence of virus-specific antiserum or pulmonary lavage fluids collected from calves 6 days after inoculation with BHV-1 or PI-3 virus. The Fc and C3b phagocytic indices of noninoculated AM, collected from 6- to 16-week-old calves, ranged from 75 to 87 and 59 to 64, respectively, and the binding indices ranged from 5 to 8 and 22 to 28, respectively. Infection of AM with either BHV-1 or PI-3 virus had no significant effect on receptor-mediated phagocytosis or binding, with the exception of a significant (P less than 0.05) decrease, from 64 to 46, of the C3b phagocytic index of PI-3 virus-infected AM. The addition of lavage fluids, collected after BHV-1 or PI-3 virus infection, to AM infected with the respective virus caused a significant (P less than 0.05) decrease in phagocytic indices with values for the Fc and C3b indices in BHV-1-infected AM decreasing from 81 to 49 and from 47 to 8, respectively, and those for the PI-3 virus-infected AM from 79 to 51 and from 46 to 15, respectively. The binding indices of virus-infected AM increased with the addition of viral lavage fluids, but the only significant (P less than 0.05) increase was for C3b binding in PI-3 virus-infected cells, which increased from 33 to 56.(ABSTRACT TRUNCATED AT 250 WORDS)     

Efficacy of viral components of a nonabortigenic combination vaccine for prevention of respiratory and reproductive system diseases in cattle

Efficacy and safety of components of an IM-administered vaccine for prevention of infectious bovine rhinotracheitis virus (IBRV), parainfluenza type-3 (PI-3) virus, bovine viral diarrhea virus (BVDV), and respiratory syncytial virus (RSV) infections and campylobacteriosis and leptospirosis were evaluated in cattle, including calves and pregnant cows. Challenge of immunity tests were conducted in calves for IBRV, PI-3 virus, or BVDV vaccinal components. All inoculated calves developed serum-neutralizing antibodies and had substantially greater protection (as measured by clinical rating systems) than did controls after challenge exposure to virulent strains of IBRV, PI-3 virus, BVDV, or RSV. In in utero tests, IBRV or bovine RSV vaccinal strains were inoculated into fetuses of pregnant cows. Histologic changes or abortions did not occur after fetal inoculation of the RSV vaccinal strain, and 10 of 14 fetuses responded serologically. Of 9 fetuses, one responded serologically to the IBRV vaccinal strain after in utero inoculation and was aborted 3 weeks later. In an immunologic interference test, 10 calves vaccinated with 2 doses of the multivalent vaccine, containing the 4 viral components and a Campylobacter-Leptospira bacterin, developed serum-neutralizing antibodies to IBRV, PI-3 virus, BVDV, and RSV without evidence of serologic interference. Under field conditions, 10,771 cattle, including 4,543 pregnant cows, were vaccinated. Vaccine-related abortions did not occur.     

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.     

Association of parainfluenza-3 virus with bovine macrophages and blood cells: an in vitro study

Bovine blood cells and peritoneal and lung macrophages were exposed in vitro to parainfluenza-3 (PI-3) virus. Residual nonadsorbed PI-3 virus (expressed in percentage of input virus) in the supernate of the various cell fractions 1 hour after incubation at 37 C was as follows: lung macrophages, 11%; peritoneal macrophages, 59%; monocytes, 26%; RBC, 14%; lymphocytes, 28%; and polymorphonuclear cells (PMN), 63%. Lung macrophages, monocytes, lymphocytes, and PMN were monitored over a 72-hour period for hemadsorption of chicken RBC. Hemadsorption increased for lung macrophages and monocytes, whereas it decreased for lymphocytes and PMN. Infective virus could not be recovered from PMN, RBC, lymphocytes, or monocytes for more than 24 hours after PI-3 infection. Recovery of infective PI-3 virus from infected peritoneal and lung macrophages extended over 4 to 8 days, respectively.     

Enhancement of the immune response and virological protection of calves against bovine herpesvirus type 1 with an inactivated gE-deleted vaccine

Four immunisation protocols based on inactivated and attenuated commercially available marker vaccines for bovine herpesvirus type 1 (BHV-1) were compared. The first group of calves were vaccinated with an attenuated vaccine administered intranasally and an inactivated vaccine injected subcutaneously, four weeks apart; the second group were vaccinated twice with the attenuated vaccine, first intranasally and then intramuscularly; the third group were vaccinated twice subcutaneously with the inactivated vaccine; and the fourth group were vaccinated twice intramuscularly with the attenuated vaccine. A control group of calves were not vaccinated. The cellular and humoral immune responses were highest in the two groups which received at least one injection of the inactivated vaccine. Virological protection was observed in all the vaccinated groups after a challenge infection and reactivation by treatment with dexamethasone, but the calves which received one dose of the inactivated vaccine as a booster or two doses of the inactivated vaccine excreted significantly less of the challenge virus than the calves which were vaccinated only with the attenuated preparation.     

Induction of antigen-specific T-cell subset activation to bovine respiratory disease viruses by a modified-live virus vaccine

OBJECTIVE: To determine the efficacy of a modified-live virus vaccine containing bovine herpes virus 1 (BHV-1), bovine respiratory syncytial virus (BRSV), parainfluenza virus 3, and bovine viral diarrhea virus (BVDV) types 1 and 2 to induce neutralizing antibodies and cell-mediated immunity in na?ve cattle and protect against BHV-1 challenge. ANIMALS: 17 calves. PROCEDURES: 8 calves were mock-vaccinated with saline (0.9% NaCl) solution (control calves), and 9 calves were vaccinated at 15 to 16 weeks of age. All calves were challenged with BHV-1 25 weeks after vaccination. Neutralizing antibodies and T-cell responsiveness were tested on the day of vaccination and periodically after vaccination and BHV-1 challenge. Specific T-cell responses were evaluated by comparing CD25 upregulation and intracellular interferon-gamma expression by 5-color flow cytometry. Titration of BHV-1 in nasal secretions was performed daily after challenge. Results-Vaccinated calves seroconverted by week 4 after vaccination. Antigen-specific cell-mediated immune responses, by CD25 expression index, were significantly higher in vaccinated calves than control calves. Compared with control calves, antigen-specific interferon-gamma expression was significantly higher in calves during weeks 4 to 8 after vaccination, declining by week 24. After BHV-1 challenge, both neutralizing antibodies and T-cell responses of vaccinated calves had anamnestic responses to BHV-1. Vaccinated calves shed virus in nasal secretions at significantly lower titers for a shorter period and had significantly lower rectal temperatures than control calves. CONCLUSION AND CLINICAL RELEVANCE: A single dose of vaccine effectively induced humoral and cellular immune responses against BHV-1, BRSV, and BVDV types 1 and 2 and protected calves after BHV-1 challenge for 6 months after vaccination.     

Cytotoxicity of bovine leucocytes for parainfluenza type-3 virus-infected cells.

The cytotoxic effect of bovine neutrophils, alveolar macrophages, monocytes and lymphocytes for parainfluenza type-3 (PI-3) virus-infected cells in 51chromium-release assays is described. Specific lysis of virus-infected target cells with PI-3 virus antibody and complement was first observed 8 h after infection coincident with the appearance of haemadsorption-positive cells. Specific lysis increased rapidly reaching a peak 18-24 h after infection. This increase was paralleled by the increase in the percentage of cells with surface haemagglutinin. Target cells were subsequently used in 51chromium-release assays between 18 and 20 h after virus infection. Antibody-independent killing of PI-3 virus-infected cells was observed with neutrophils, alveolar macrophages and lymphocytes. Levels of specific lysis up to 30% for neutrophils and 68% for alveolar macrophages were observed, although there was considerable variation in activity from animal to animal. Lymphocyte preparations showed levels of cytotoxicity up to 20% in some cases while monocytes had low killing ability. Addition of PI-3 virus-specific antibodies enhanced killing by neutrophils, monocytes and lymphocytes but inhibited killing by alveolar macrophages. Complement, particularly guinea pig complement, was cytotoxic for virus-infected but not for uninfected cells, and also considerably enhanced the cytotoxic effect of neutrophils and lymphocytes.     

Bovine viral diarrhea viral infections in feeder calves with respiratory disease: interactions with Pasteurella spp., parainfluenza-3 virus, and bovine respiratory syncytial virus.

The prevalence of bovine viral diarrhea virus (BVDV) infections was determined in a group of stocker calves suffering from acute respiratory disease. The calves were assembled after purchase from Tennessee auctions and transported to western Texas. Of the 120 calves, 105 (87.5%) were treated for respiratory disease. Sixteen calves died during the study (13.3%). The calves received a modified live virus BHV-1 vaccine on day 0 of the study. During the study, approximately 5 wk in duration, sera from the cattle, collected at weekly intervals, were tested for BVDV by cell culture. Sera were also tested for neutralizing antibodies to BVDV types 1 and 2, bovine herpesvirus-1 (BHV-1), parainfluenza-3 virus (PI-3V), and bovine respiratory syncytial virus (BRSV). The lungs from the 16 calves that died during the study were collected and examined by histopathology, and lung homogenates were inoculated onto cell cultures for virus isolation. There were no calves persistently infected with BVDV detected in the study, as no animals were viremic on day 0, nor were any animals viremic at the 2 subsequent serum collections. There were, however, 4 animals with BVDV type 1 noncytopathic (NCP) strains in the sera from subsequent collections. Viruses were isolated from 9 lungs: 7 with PI-3V, 1 with NCP BVDV type 1, and 1 with both BVHV-1 and BVDV. The predominant bacterial species isolated from these lungs was Pasteurella haemolytica serotype 1. There was serologic evidence of infection with BVDV types 1 and 2, PI-3V, and BRSV, as noted by seroconversion (> or = 4-fold rise in antibody titer) in day 0 to day 34 samples collected from the 104 survivors: 40/104 (38.5%) to BVDV type 1; 29/104 (27.9%) to BVDV type 2; 71/104 (68.3%) to PI-3V; and 81/104 (77.9%) to BRSV. In several cases, the BVDV type 2 antibody titers may have been due to crossreacting BVDV type 1 antibodies; however, in 7 calves the BVDV type 2 antibodies were higher, indicating BVDV type 2 infection. At the outset of the study, the 120 calves were at risk (susceptible to viral infections) on day 0 because they were seronegative to the viruses: 98/120 (81.7%), < 1:4 to BVDV type 1; 104/120 (86.7%) < 1:4 to BVDV type 2; 86/120 (71.7%) < 1:4 to PI-3V; 87/120 (72.5%) < 1:4 to BRSV; and 111/120 (92.5%) < 1:10 to BHV-1. The results of this study indicate that BVDV types 1 and 2 are involved in acute respiratory disease of calves with pneumonic pasteurellosis. The BVDV may be detected by virus isolation from sera and/or lung tissues and by serology. The BVDV infections occurred in conjunction with infections by other viruses associated with respiratory disease, namely, PI-3V and BRSV. These other viruses may occur singly or in combination with each other. Also, the study indicates that purchased calves may be highly susceptible, after weaning, to infections by BHV-1, BVDV types 1 and 2, PI-3V, and BRSV early in the marketing channel.     

Effects of bovine parainfluenza-3 virus on phagocytosis and phagosome-lysosome fusion of cultured bovine alveolar macrophages

Bovine parainfluenza-3 virus (PI-3V) replicated in cultured bovine alveolar macrophages (BAM) in vitro. Cytopathic changes included spindle cell and giant cell formation, diffuse cell lysis, and cellular detachment progressing to total destruction of the monolayer. Direct immunofluorescent microscopy revealed viral antigen in greater than 90% of BAM on post-inoculation day (PID) 3. Virus titers in culture supernatants increased by a factor of 1.6 X 10(6) TCID50 by PID 6. Candida glabrata was phagocytized by a similar proportion of glass-adherent PI-3V-infected and sham-inoculated control BAM. However, when the number of glass-adherent cells available for assay was taken into account (normalization), the percentage of phagocytic PI-3V-infected BAM was significantly lower than that of the control cells at PID 5 and 7 (P less than 0.01). Phagosome-lysosome fusion assays had a marked reduction of fusion activity in PI-3V-infected BAM as compared with that of control BAM. Proportions of infected cells that showed fusion were approximately 50% of that of the control cells at PID 4 and 6 (P less than 0.05). Normalization of these values reduced the fusion rate of PI-3V-infected BAM to 34% of that of control BAM (P less than 0.01).     

Evaluation of a quadrivalent inactivated vaccine for the protection of cattle against diseases due to common viral infections

Efficacy of an inactivated quadrivalent vaccine containing infectious bovine rhinotracheitis (IBR) virus, parainfluenza type 3 (PI3) virus, bovine virus diarrhoea virus (BVDV) and bovine respiratory syncytial virus (BRSV) was assessed in naive bovine calves to evaluate short-term (4-18 weeks) and long-term (24-38 weeks) protection following the basic intramuscular vaccination regime of 2 inoculations a month apart. Vaccination was staggered between the long-term and the short-term groups by about 5 months so that both groups, along with a matched group of 6 unvaccinated (control) calves, could be challenged at the same time. Sequential challenges at intervals of 3-8 weeks were done in the order: IBR virus (intranasally, IN), PI3 virus (IN and intratracheally, IT), pestiviruses (IN) and BRSV (IN and IT). The IBR virus challenge produced febrile rhinotracheitis (FRT) in control calves but both the severity and the duration of FRT was significantly reduced in both vaccinated groups. The amount and the duration of IBR virus shed by the vaccinated groups was significantly reduced compared to the control group. Although PI3 virus, pooled pestivirus and BRSV challenges did not result in a noteworthy disease, challenge virus shedding (amount and duration) from the upper (all 3 viruses) and the lower (BRSV) respiratory tracts was significantly reduced in vaccinated groups. After pestivirus challenge, sera and leukocytes from all control calves were infectious for 6-9 days whereas virus was recovered only from leukocytes in vaccinated calves and only for 1.6-2.7 days. Thus a standard course of the quadrivalent vaccine afforded a significant protection against IBR virus, PI3 virus, BVDV and BRSV for at least 6 months.     

Efficacy of an intranasal modified live bovine respiratory syncytial virus and temperature-sensitive parainfluenza type 3 virus vaccine in 3-week-old calves experimentally challenged with PI3V

Two experimental parainfluenza type 3 virus (PI3V) challenge studies were undertaken to evaluate the efficacy of a single intranasal dose of an attenuated live vaccine containing modified live bovine respiratory syncytial virus (BRSV) and temperature-sensitive PI3V in 3-week-old calves. In the first study, vaccine efficacy was evaluated in colostrum deprived calves. Nasal shedding of PI3V was highly significantly reduced in vaccinated calves challenged 10 days or 21 days after vaccination. In the second study, vaccine efficacy was assessed in calves with maternal antibodies against PI3V by challenge 66 days post-vaccination. Vaccination also significantly reduced PI3V excretion after challenge in this study. In both studies, clinical signs after challenge were very mild and were not different between vaccinated and control calves.