Genomic and antigenic characterization of bovine parainfluenza-3 viruses in the United States including modified live virus vaccine (MLV) strains and field strains from cattle.

This study investigated the genetic and antigenic characterization of parainfluenza-3 virus (PI3V) of cattle. Using molecular tests including real time PCR and viral genome sequencing, PI3V strains could be separated into PI3V types, including PI3V A, PI3V B, and PI3V C. Isolates from cattle with bovine respiratory disease clinical signs and commercial vaccines in the U.S. with MLV PI3V were typed using these molecular tests. All the MLV vaccine strains tested were PI3V A. In most cases PI3V field strains from calves receiving MLV vaccines were types heterologous to the vaccine type A. Also antigenic differences were noted as PI3V C strains had lower antibody levels than PI3V A in serums from cattle receiving MLV PI3V A vaccines. This study further demonstrates there is genetic variability of U.S. PI3V strains and also antigenic variability. In addition, isolates from cattle with BRD signs and receiving MLV vaccines may have heterologous types to the vaccines, and molecular tests should be performed to differentiate field from vaccine strains. Potentially the efficacy of current PI3V A vaccines should be evaluated with other types such a PI3V B and PI3V C.

Detection and characterization of viruses as field and vaccine strains in feedlot cattle with bovine respiratory disease.

This study investigated viruses in bovine respiratory disease (BRD) cases in feedlots, including bovine herpesvirus-1 (BoHV-1), bovine viral diarrhea virus (BVDV), bovine respiratory syncytial virus (BRSV), bovine coronaviruses (BoCV) and parainfluenza-3 virus (PI3V). Nasal swabs were collected from 114 cattle on initial BRD treatment. Processing included modified live virus (MLV) vaccination. Seven BRD necropsy cases were included for 121 total cases. Mean number of days on feed before first sample was 14.9 days. Swabs and tissue homogenates were tested by gel based PCR (G-PCR), quantitative-PCR (qPCR) and quantitative real time reverse transcriptase PCR (qRT-PCR) and viral culture. There were 87/114 (76.3%) swabs positive for at least one virus by at least one test. All necropsy cases were positive for at least one virus. Of 121 cases, positives included 18/121 (14.9%) BoHV-1; 19/121 (15.7%) BVDV; 76/121 (62.8%) BoCV; 11/121 (9.1%) BRSV; and 10/121 (8.3%) PI3V. For nasal swabs, G-PCR (5 viruses) detected 44/114 (38.6%); q-PCR and qRT-PCR (4 viruses) detected 81/114 (71.6%); and virus isolation detected 40/114 (35.1%). Most were positive for only one or two tests, but not all three tests. Necropsy cases had positives: 5/7 G-PCR, 5/7 q-PCR and qRT-PCR, and all were positive by cell culture. In some cases, G-PCR and both real time PCR were negative for BoHV-1, BVDV, and PI3V in samples positive by culture. PCR did not differentiate field from vaccines strains of BoHV-1, BVDV, and PI3V. However based on sequencing and analysis, field and vaccine strains of culture positive BoHV-1, BoCV, BVDV, and PI3V, 11/18 (61.1%) of BoHV-1 isolates, 6/17 (35.3%) BVDV isolates, and 1/10 (10.0%) PI3V identified as vaccine. BRSV was only identified by PCR testing. Interpretation of laboratory tests is appropriate as molecular based tests and virus isolation cannot separate field from vaccine strains. Additional testing using sequencing appears appropriate for identifying vaccine strains.

Bovine coronaviruses from the respiratory tract: antigenic and genetic diversity.

BoCV isolated from respiratory tract, nasal swab and broncho alveolar washing fluid samples were evaluated for genetic and antigenic differences. These BoCV from the respiratory tract of healthy and clinically ill cattle with BRD signs were compared to reference and vaccine strains based on Spike protein coding sequences and VNT using convalescent antisera. Based on this study, the BoCV isolates belong to one of two genomic clades (clade 1 and 2) which can be differentiated antigenically. The respiratory isolates from Oklahoma in this study were further divided by genetic differences into three subclades, 2a, 2b, and 2c. Reference enteric BoCV strains and a vaccine strain were in clade 1. Currently available vaccines designed to control enteric disease are based on viruses from one clade while viruses isolated from respiratory tracts, in this study, belong to the other clade.

Humoral immune response and assessment of vaccine virus shedding in calves receiving modified live virus vaccines containing bovine herpesvirus-1 and bovine viral diarrhoea virus 1a.

Susceptible calves were administered modified live virus (MLV) vaccines containing bovine herpesvirus-1 (BHV1) and bovine viral diarrhoea type 1 (BVDV1a) strains intramuscularly, with one vaccine containing both MLV and inactivated BHV-1 and inactivated BVDV1a. There was no evidence of transmission of vaccine (BHV-1 and BVDV1a) strains to susceptible non-vaccinated controls commingled with vaccinates. No vaccinates had detectable BHV-1 in peripheral blood leucocytes (PBL) after vaccination. Each of three vaccines containing an MLV BVDV1a strain caused a transient BVDV vaccine induced viremia in PBL after vaccination, which was cleared as the calves developed serum BVDV1 antibodies. The vaccine containing both MLV and inactivated BHV-1 induced serum BHV-1 antibodies more rapid than MLV BHV-1 vaccine. Two doses of MLV BHV-1 (days 0 and 28) in some cases induced serum BHV-1 antibodies to higher levels and greater duration than one dose.

Bovine viral diarrhea virus types 1 and 2 antibody response in calves receiving modified live virus or inactivated vaccines.

Serums from calves receiving eight different commercial vaccines containing modified live virus (MLV) or inactivated bovine viral diarrhea virus (BVDV) immunogens were assayed for antibodies to types 1 and 2 BVDV strains. The immune response to the types 1 and 2 BVDV strains were evaluated in 48 calves receiving one of the eight vaccines for each group. For 7/8 vaccines, the BVDV vaccine immunogen was only type 1 whereas the remaining vaccine contained both types 1 and 2 immunogens. Calves administered MLV vaccine received only one dose at day 0, whereas those calves receiving the inactivated vaccines were administered two doses initially at days 0 and 28. Selected calves were revaccinated with only one dose at day 140. Animals vaccinated with type 1 vaccines developed titers to a broad range of type 1 BVDV, both cytopathic (CP) and noncytopathic (NCP) biotypes, with lower titers evident to type 2 BVDV strains. For some animals, the BVDV serum antibodies did not persist. Revaccination at day 140 induced a significant four-fold increase in animals with intermediate to low antibody titers. There did not appear to be any clear differences in antibody responses between type 1 MLV or inactivated vaccines. The calves receiving the inactivated vaccine containing types 1 and 2 had similar antibody levels to both types.

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.

Bovine viral diarrhea virus cytopathic and noncytopathic biotypes and type 1 and 2 genotypes in diagnostic laboratory accessions: clinical and necropsy samples from cattle.

One hundred three bovine samples submitted to the Oklahoma Animal Disease Diagnostic Laboratory (OADDL) that were positive for bovine viral diarrhea virus (BVDV) were typed by a nested reverse transcription-polymerase chain reaction for BVDV genotypes. These BVDV samples included supernatants from virus isolation (79), serums (17), and buffy coats (7). The biotype, cytopathic (CP) or noncytopathic (NCP), was determined by cell culture virus isolation. Twenty-eight of 103 samples were submitted for herd screening for BVDV, 32 from OADDL necropsy cases, and 43 from live cattle with varied clinical conditions. Two samples contained 2 bands indicating presence of both BVDV types 1 and 2. Of the 105 BVDV samples, 26 were type 1 CP strains (24.8%), 38 were type 1 NCP strains (36.2%), 10 were type 2 CP strains (9.5%), and 31 were type 2 NCP strains (29.5%). From the 105 BVDV isolates, NCP biotypes were isolated more frequently (69, 65.7%) than CP biotypes (36, 34.3%), and type 1 genotypes were more frequently isolated (64, 61.00%) than type 2 genotypes (41, 39.0%). The NCP strains were more common than CP in herd screening samples. Cattle with respiratory disease history at time of sampling had more NCP than CP biotypes and more type 1 than type 2 genotypes. Of the necropsy cases, more were type 1 than type 2 genotypes for the respiratory cases with fibrinous pneumonia, more were type 1 than type 2 genotypes in cattle with enteritis/colitis without systemic lesions, and more were CP than NCP biotypes in cattle with enteritis/colitis with systemic lesions. No CP biotype was isolated from serum samples.

Nested reverse transcriptase-polymerase chain reaction (RT-PCR) for typing ruminant pestiviruses: bovine viral diarrhea viruses and border disease virus.

A nested reverse transcription (RT) polymerase chain reaction (PCR) assay was evaluated for differentiating reference bovine viral diarrhea virus (BVDV) strains, BVDV from diagnostic accessions, modified-live virus (MLV) BVDV strains in bovine viral vaccines, and a reference border disease virus (BDV). The detection level of this assay was compared to viral infection in cell culture. The PCR assay was used to distinguish 3 ruminant pestiviruses, types 1 and 2 BVDV, and type 3 BDV. The consensus (first) PCR assay detected all 3 ruminant pestiviruses, a result of the shared sequence homology. The consensus PCR product was subjected to a second (nested) PCR which used type-specific primers. The nested PCR was able to differentiate the 3 ruminant pestiviruses. Viral stocks of BVDV were diluted 10-fold and processed for the 2-step PCR assay. The sensitivity of this 2-step PCR assay was compared to viral infectivity in cell culture based on identical volumes of the system tested (cell culture assay and processing for RNA). The RT-PCR type-specific assay differentiated BVDV laboratory reference strains (12), diagnostic laboratory isolates (15), 2 MLV BVDV vaccine strains, and a BDV strain. The 30 ruminant pestiviruses typed included: (1) 27 reference strains and diagnostic laboratory isolates; 18 cytopathic (CP) type 1 strains, 3 CP type 2 strains, 3 noncytopathic (NCP) type 1 strains, and 3 NCP type 2 strains; (2) 2 MLV strains, type 1; and (3) 1 CP BDV type 3. The PCR assay had a detection limit of 10 TCID50/0.025 mL of virus when 3 separate BVDV were tested. This 2 step RT-PCR assay would be useful for the typing of ruminant pestiviruses, particularly BVDV isolates from the diagnostic laboratory.

Neutralizing antibodies to type 1 and 2 bovine viral diarrhea viruses: detection by inhibition of viral cytopathology and infectivity by immunoperoxidase assay.

Neutralizing antibodies to type 1 and 2 bovine viral diarrhea virus (BVDV) strains were measured by a microtiter virus neutralization test (MVNT) in cell culture. Antibodies (neutralizing) were detected by inhibition of viral infectivity, by the absence of viral cytopathology for cytopathic strains, or by immunoperoxidase staining for noncytopathic strains. The immunoperoxidase-stained monolayers could be detected without the aid of light microscopy. Twenty BVDV strains were used as challenge viruses in the in vitro MVNT, including 14 type 1 and 6 type 2 strains. Representative noncytopathic and cytopathic strains of both types were used. Positive control serum samples available for diagnostic testing contained both type 1 and type 2 BVDV antibodies. There did not appear to be major differences in antibody titers among the respective type strains, regardless of biotype (cytopathic or noncytopathic). In a study with sera from calves receiving a modified live virus or inactivated BVDV vaccine, the calves receiving type 1 strains responded with higher antibody titers to type 1 strains than to type 2 strains.

Action of quail and chicken interferons on a quail cell line, QT35.

Production of interferon (IFN) in quail cells (QT35) and the activity of quail IFN and heterologous avian IFN (chicken) on QT35 cells were examined. Quail cells produced IFN after induction by bluetongue virus serotype 10; chicken and quail IFN conferred antiviral resistance on the quail cells. Both chicken and quail IFN induced increased levels of 2',5'-oligoadenylate synthetase (2',5'-OAS) in QT35 cells and reduced levels of intracellular Salmonella typhimurium postchallenge. These results indicate that the quail cells produce IFN and respond to homologous and heterologous avian IFN as evidenced by enhanced (1) resistance to viral infection, (2) production of 2',5'-OAS, and (3) resistance to invasion by bacteria. QT35 quail cell monolayer cultures offer an alternative to primary chicken embryo fibroblasts cultures used for avian IFN studies.

Antibody responses by cattle after vaccination with commercial viral vaccines containing bovine herpesvirus-1, bovine viral diarrhea virus, parainfluenza-3 virus, and bovine respiratory syncytial virus immunogens and subsequent revaccination at day 140.

Calves were vaccinated with four different commercial viral vaccines containing bovine herpesvirus-1 (BHV-1), bovine viral diarrhea (BVDV), parainfluenza-3 virus (PI-3V), and bovine respiratory syncytial virus (BRSV) immunogens. For the initial vaccination certain vaccines were given twice (days 0 and 28), whereas other vaccines were given on day 0. The calves received another injection on day 140 with the vaccine originally given on day 0. The sera were collected at days 0, 7, 14, 21, 28, 42, 56, 84, 112, 140, 154, 168, and 196 and assayed for viral neutralizing antibodies. The calves were seronegative to BHV-1, BVDV, and BRSV at the onset of the experiment; however, the calves were PI-3V antibody positive due to prior active infection. The commercial vaccines were: (I) inactivated; (II) modified live virus (MLV); (III) combination of chemically altered live virus, MLV, and inactivated virus; and (IV) combination of inactivated and MLV. Among the vaccine groups there were differences in onset and duration of antibodies as measured by geometric mean titers to each immunogen in postvaccination collection dates compared to day 0 titers; and likewise compared to day 140 titers after revaccination at day 140. There were also differences in antibody titers to the various viruses among the vaccine groups on specific collection dates. All four vaccines induced increased BHV-1 antibodies by day 14 after the initial injection. The antibody titers induced by MLV BHV-1 and the chemically altered BHV-1 vaccines had greater duration than those induced by the inactivated vaccine.(ABSTRACT TRUNCATED AT 250 WORDS)

The role of NMDA and sigma systems in the behavioral effects of phencyclidine in preweanling rats.

To determine the role of NMDA receptor blockade and sigma receptors in the behavioral effects of PCP during development, we assessed the behavioral effects of PCP, (+)-MK-801 and 1,3-Di(2-tolyl)guanidine (DTG) in preweanling rats. In the first experiment, rats were injected sc on postnatal day (PND) 19 with 0.5-4.5 mg/kg PCP, and locomotor activity and wall climbing behavior were scored. PCP induced high levels of locomotor activity on PND 19 in a dose dependent manner with the 2.0 mg/kg dose producing the greatest activity. In the second experiment, rats were injected on PND 12 or 19 with 1.0-4.0 mg/kg PCP or 0.1-0.4 mg/kg (+)-MK-801 and tested using the same procedures. Both PCP and (+)-MK-801 induced activity increases on PND 19 in a dose dependent manner, with 2.0 and 3.0 mg/kg PCP and 0.2 mg/kg (+)-MK-801 inducing the highest activity levels. Peak activity levels on PND 12 were approximately 30% of those observed on PND 19, with the lowest dose of PCP and (+)-MK-801 producing the greatest activity. Large amounts of wall climbing behavior were elicited by PCP on PND 12, whereas (+)-MK-801 induced only minor amounts of wall climbing. In the third experiment, the effects of 0, 1, 3, 6, or 12 mg/kg DTG were examined in PND 13-14 and 16-17 rats. DTG had little effect on locomotor activity on PND 13-14, although the highest dose did inhibit activity. On PND 16-17, all doses of DTG tended to increase locomotor activity. The results suggest (1) the robust locomotor effects of PCP on PND 19 are mediated in part by NMDA mechanisms (2) this period of increased sensitivity to both PCP and (+)-MK-801 might represent a critical period of development when systems mediating locomotor activity are vulnerable to neurotoxic insult (3) NMDA blockade alone does not mediate PCP-induced wall climbing behavior and (4) that at the doses of DTG and the ages tested, sigma receptors do not play a role in the locomotor-inducing effects of PCP.

Effects of labetalol on cocaine pharmacokinetics in neonatal piglets.

Developmental exposure to cocaine can produce adverse neurobehavioral and cardiovascular effects. Few animal models of human neonatal exposure have been established. A pharmacokinetic study was therefore conducted to characterize the disposition of cocaine and a major metabolite benzoylecgonine (BE) using piglets as an animal model. Eight piglets (postnatal days 8-9) were instrumented with a jugular cannula for drug administration and blood sampling. One group of subjects (controls) received 6.0 mg/kg of cocaine-HCl (i.v.) and blood samples were drawn over 0-24 h. In another group (labetalol), 0.25 mg/kg labetalol-HCl was coadministered 15 min following cocaine dosing. Plasma levels of cocaine and BE were determined using GC-MS methods. Pharmacokinetics were evaluated by using a model-independent approach and compartmental modeling. For controls model-independent results were as follows: AUC = 148.9 +/- 9.0 mg/l x min, systemic clearance = 0.041 +/- 0.003 liters/min/kg, volume of distribution = 1.543 +/- 0.470 liters/kg, and t1/2 beta = 29.4 +/- 6.8 min. Cocaine followed two-compartment model kinetics with distribution and elimination half-lives of 0.3 +/- 0.1 and 58.0 +/- 18.0 min, respectively. Labetalol significantly decreased systemic clearance to 0.029 +/- 0.004 liters/min/kg. BE kinetics revealed a elimination half-life of 230.0 +/- 83.2 min. The results demonstrate a rapid distribution and metabolism of cocaine to BE followed by a prolonged elimination phase which is extended by labetalol treatment.

The ontogeny of phencyclidine-induced wall climbing and locomotor activity.

Wall climbing behavior is an age-specific behavior that is elicited during postnatal Days 7 through 17 by various stimuli that include heat, odors, shock, and the catecholaminergic agonists apomorphine, amphetamine, and clonidine. In a previous study, a significant amount of wall climbing behavior was observed during ataxia and activity testing following phencyclidine (PCP) administration in Day 19 but not Day 40 rat pups. The present study describes the ontogeny of PCP-induced wall climbing behavior and locomotor activity. Frequency and duration of wall climbing bouts and locomotor activity were recorded on Days 5, 12, 19, 26, 33, or 40 following PCP treatment. On Day 12, all doses of PCP induced significant amounts of wall climbing behavior. A similar pattern of results was observed on Day 5 although these effects were not statistically significant. After Day 12, PCP-induced wall climbing behavior declined precipitously. PCP increased locomotor activity at all ages tested with maximum activities observed on Day 19. These results demonstrate that PCP-elicited wall climbing behavior follows an ontogenetic profile similar to that previously reported for other stimuli and that there are robust ontogenetic differences in the locomotor response to PCP.

Interferon and 2',5'-oligo(A) synthetase activities in serum and blood mononuclear leukocytes of cattle after injection of bovine interferon-alpha 1.

Cell extracts that were prepared from blood mononuclear leukocytes from 66 samples obtained from 6 clinically normal calves contained mean 2',5'-oligoadenylate (2',5'-oligo[A]) synthetase activity sufficient to synthesize 186 +/- 82 pmol of 2',5'-oligo(A)/h/10(6) cells. Calves had no measurable serum interferon (IFN) activity. Five calves were given IM injections of 10(4), 10(5), 5 x 10(5), 10(6), and 10(7) U of bovine IFN-alpha 1/kg of body weight at 2-week intervals. Five dosing sequences were used with a 5 x 5 Latin square design so that each calf received each dose once. Activity of 2',5'-oligo(A) synthetase increased at 24 hours in response to all dosages of IFN and then declined following first-order kinetics, with an apparent half-life (t1/2) of 2.1 +/- 0.5 days. The area under the concentration-time curve for 2',5'-oligo(A) synthetase increased with dose of IFN more rapidly than did peak response. Serum IFN that was measured at 1-day intervals following administration of IFN was consistently measurable only at dosages above 10(6) U of IFN/kg. The t1/2 for circulating IFN was 12.4 +/- 1.0 hours. Over all dosages, increases in 2',5'-oligo(A) synthetase activity were measurable for 3.5 days longer than were increases in IFN following IM injection of IFN. None of the calves developed detectable anti-IFN antibodies.

Neutralizing antibody responses to bluetongue and epizootic hemorrhagic disease virus serotypes in beef cattle.

Blood samples were obtained from sentinel beef cattle at monthly intervals, and the sera were tested for antibodies, using a bluetongue virus (BTV) immunodiffusion test (IDT) and virus-neutralization test (VNT), for 5 BTV serotypes (2, 10, 11, 13, and 17) and 2 epizootic hemorrhagic disease virus (EHDV) serotypes (1 and 2). The cattle tested were transported from Tennessee to Texas in 1984 and 1985. All cattle were seronegative by the BTV IDT at the initial bleeding in Texas in 1984 and 1985. In 1984, 16 of 40 (40%) cattle seroconverted as assessed by results of the BTV IDT. In the 16 seropositive cattle in 1984, neutralizing antibodies were detected to BTV serotypes 10 (n = 7), 11 (n = 3), and 17 (n = 11), and EHDV serotypes 1 (n = 1) and 2 (n = 7). In 1984, no cattle seroconverted to BTV-2 or BTV-13. In 1985, 10 of 36 (27.8%) cattle seroconverted as assessed by results of the IDT. Of the 10 seropositive cattle in 1985, neutralizing antibodies were detected to BTV serotypes 10 (n = 10), 11 (n = 10), 13 (n = 7), and 17 (n = 5), and EHDV serotypes 1 (n = 1) and 2 (n = 7). In 1985, no cattle seroconverted to BTV-2. Clinical diseases attributable to BTV or EHDV was not detected in these cattle in 1984 or 1985.

Effect of recombinant DNA-derived bovine and human interferons on replication of bovine herpesvirus-1, parainfluenza-3, and respiratory syncytial viruses.

Antiviral effects of recombinant DNA-derived bovine (Bo) and human (Hu) interferons (IFN) on the replication of bovine herpesvirus-1, parainfluenza-3, and respiratory syncytial viruses were studied. Bovine monolayer cultures were treated with recombinant DNA-produced Bo IFN-alpha 1, Bo IFN-beta 2, Hu IFN-alpha A, or Hu IFN-alpha A/D and then challenge exposed with bovine herpesvirus-1, bovine parainfluenza-3 virus, bovine respiratory syncytial virus, or vesicular stomatitis virus. Treatment with each IFN reduced the viral yield for each of these viruses, compared with that of control cultures.

Susceptibility of feline herpesvirus 1 and a feline calicivirus to feline interferon and recombinant human leukocyte interferons.

Feline lung monolayer cultures were treated with either a feline interferon (IFN) or one of two recombinant human alpha-IFNs and then challenged with feline herpesvirus 1 (FHV-1), feline calicivirus (F-9 strain), or vesicular stomatitis virus. Treatment with these IFNs reduced the viral yield for each of these three viruses as compared with that of control cultures. Vesicular stomatitis virus was more sensitive to each IFN than were FHV-1 or feline calicivirus F-9.