Safety, efficacy and cross-protectivity of a live intranasal aerosol haemorrhagic septicaemia vaccine

The safety, efficacy and cross-protectivity of a live intranasal aerosol haemorrhagic septicaemia vaccine containing Pasteurella multocida serotype B:3,4 were tested in young cattle and buffaloes in Myanmar, where more than 1.5 million animals had been inoculated with this vaccine between 1989 and 1999. A recommended dose of 2 x 10(7) viable organisms was used for the efficacy test. The administration of 100 times the recommended dose to 50 cattle and 39 buffalo calves was innocuous. Seven months after they were vaccinated, three of three buffaloes were protected and 12 months after they were vaccinated, three of four buffaloes were protected against a subcutaneous challenge with serotype B:2 which killed three of three unvaccinated buffaloes. Twelve months after they were vaccinated, eight of eight cattle survived a serotype B:2 challenge, which killed four of four unvaccinated controls. The vaccinated cattle had developed serum antibodies detectable by the passive mouse protection test. Indirect haemagglutination tests on sera taken from cattle 10 days and five weeks after they were vaccinated showed high titres of antibodies. The serum of vaccinated cattle cross-protected passively immunised mice against infection with P. multocida serotypes E:2, F:3,4 and A:3,4.     

The effect of dose, route and virulence of bovine herpesvirus 1 vaccine on experimental respiratory disease in cattle.

Three experiments were conducted with calves in which, following intramuscular or intranasal vaccination with virulent or attenuated bovine herpesvirus 1, calves were protected against bovine herpesvirus 1 -- Pasteurella haemolytica challenge. Calves receiving low doses of vaccine had lower levels of antibody and greater evidence of virus replication upon challenge than those receiving higher doses. In contrast 11/13 unvaccinated controls had fibrino-purulent pneumonia following challenge. The immune response developed later in younger calves and those given low doses of vaccine. Neutralizing antibodies to bovine herpes-virus 1 were not found in nasal secretions, but were present in serum seven days after vaccination. Bovine herpesvirus 1 was isolated before challenge from nasal secretions of calves vaccinated intranasally or intramuscularly with virulent virus but not those vaccinated intramuscularly with vaccine virus. It was concluded that both routes of vaccination with either virulent or attenuated bovine herpesvirus 1 provided protection from challenge with homologous or heterologous bovine herpesvirus 1 and that live vaccines should contain at least 10(3) plaque forming units/dose for effective immunization.     

The immunization of calves against heartwater: subsequent immunity both in the absence and presence of natural tick challenge

Cattle, vaccinated as calves with Cowdria ruminantium-infected tick stabilate, were challenged 6, 12 and 24 months later. In the absence of tick challenge, vaccination of calves induced a partial immunity against subsequent challenge at 12 and 24 months. In animals exposed to ticks, the resistance was no better than that of control, unvaccinated cattle. When they were challenged at 6 months of age there was no difference between vaccinated and unvaccinated calves, either in the absence or presence of tick challenge, and all the animals manifested a high degree of natural resistance. This study therefore suggests that the value of vaccinating Afrikander-cross calves in heartwater endemic areas should be further investigated. The indirect fluorescent antibody (IFA) test proved to be a valuable means of monitoring the serological response of vaccinated animals and detecting the sero-conversion of animals exposed to tick infection. On one hand, there was good correlation between the febrile reaction and the results of the IFA test on the sera of vaccinated and control cattle challenged with the heartwater agent, in that all sero-positive animals were resistant to challenge. On the other hand, though, a considerable percentage of the animals that were serologically negative were also resistant to challenge.     

Prevention of haemorrhagic septicaemia in buffaloes and cattle with a live vaccine

Young cattle and buffaloes were vaccinated subcutaneously and intradermally with a live vaccine containing Pasteurella multocida serotype B:3,4. Twelve months after vaccination three of five young cattle in the subcutaneously vaccinated group and three of four in the intradermally vaccinated group were protected against serotype B:2 challenge. Eleven buffaloes vaccinated subcutaneously and two vaccinated intradermally survived the same challenge 13 months after vaccination.     

Protection of piglets against atrophic rhinitis by vaccinating the sow with a vaccine against Pasteurella multocida and Bordetella bronchiseptica

The efficacy of a new vaccine against atrophic rhinitis in pigs was tested in the Netherlands and Denmark. The vaccine contained protein dO (a truncated Pasteurella multocida toxin which is immunogenic and non-toxic), inactivated Bordetella bronchiseptica whole cells, and an adjuvant. The sows were either vaccinated intramuscularly with 2 ml of the vaccine at six to eight and two to four weeks before expected farrowing or left unvaccinated as controls. All the piglets were challenged intranasally with B bronchiseptica when three to seven days old and with P multocida three to four days later. Pigs born to the vaccinated sows performed significantly better than pigs born to the control sows when judged on growth, average daily weight gain and snout scores. The challenge organisms were reisolated more frequently from the control pigs than from the pigs in the vaccinated group. The vaccinated sows and their progeny developed high titres of antibodies against B bronchiseptica and P multocida toxin.     

Update on vaccination of cattle and wildlife populations against tuberculosis

A recombinant bovine herpesvirus 5 lacking thymidine kinase and glycoprotein E genes (BoHV-5gEΔTKΔ) was evaluated as a live experimental vaccine. In a first experiment, ten-months-old calves were vaccinated intramuscularly (n=9) or remained as controls (n=8) and 42 days later were challenged with BoHV-5 or BoHV-1 intranasally. The four control calves challenged with BoHV-5 developed severe depression and neurological signs and were euthanized in extremis at days 13 and 14 pos-infection (pi); the five vaccinated animals challenged with BoHV-5 remained healthy. The titers of virus shedding were reduced (p<0.01) from days 3 to 7 post-infection (pi) in vaccinated animals. Control and vaccinated calves challenged with BoHV-1 presented mild transient respiratory signs; yet the magnitude of virus shedding was reduced (p<0.05) in vaccinated animals (days 5, 9 and 11pi). In a second experiment, young calves (100-120 days-old) were vaccinated (n=15) or kept as controls (n=5) and subsequently challenged with a BoHV-1 isolate. Control calves developed moderate to severe rhinitis and respiratory distress; two were euthanized in extremis at days 5 and 9 pi, respectively. In contrast, vaccinated animals were protected from challenge and only a few developed mild and transient nasal signs. The duration and titers of virus shedding after challenge were reduced (p<0.05) in vaccinated animals comparing to controls. In both experiments, vaccinated animals developed antibodies to gE only after challenge. These results demonstrate homologous and heterologous protection and are promising towards the use of the recombinant BoHV-5gEΔTKΔ in vaccine formulations to control BoHV-5 and BoHV-1 infections.     

Assessment of efficacy of a bivalent BTV-2 and BTV-4 inactivated vaccine by vaccination and challenge in cattle

The efficacy of a bivalent inactivated vaccine against bluetongue virus (BTV) serotypes 2 (BTV-2) and 4 (BTV-4) was evaluated in cattle by general and local examination, serological follow-up, and challenge. Thirty-two 4-month-old calves were randomly allocated into 2 groups of 16 animals each. One group was vaccinated subcutaneously (s/c) with two injections of bivalent inactivated vaccine at a 28-day interval, and the second group was left unvaccinated and used as control. Sixty-five days after first vaccination, 8 vaccinated and 8 unvaccinated calves were s/c challenged with 1 mL of 6.2 Log10 TCID50/mL of an Italian field isolate of BTV serotype 2, while the remaining 8 vaccinated and 8 unvaccinated animals were challenged by 1 mL of 6.2 Log10 TCID50/mL of an Italian field isolate of BTV serotype 4. Three additional calves were included in the study and used as sentinels to confirm that no BTV was circulating locally. At the time of the challenge, only one vaccinated animal did not have neutralizing antibodies against BTV-4, while the remaining 15 showed titres of at least 1:10 for either BTV-2 or BTV-4. However, the BTV-2 component of the inactivated vaccine elicited a stronger immune response in terms of both the number of virus neutralization (VN) positive animals and antibody titres. After challenge, no animal showed signs of disease. Similarly, none of the vaccinated animals developed detectable viraemia while bluetongue virus serotype 2 and 4 titres were detected in the circulating blood of all unvaccinated animals, commencing on day 3 post-challenge and lasting 16 days. It is concluded that administration of the bivalent BTV-2 and BTV-4 inactivated vaccine resulted in a complete prevention of detectable viraemia in all calves when challenged with high doses of BTV-2 or BTV-4.     

Efficacy of intranasal vaccination of field buffaloes against haemorrhagic septicaemia with a live gdhA derivative Pasteurella multocida B:2

The efficacy of an intranasal haemorrhagic septicaemia vaccine containing live gdhA derivative Pasteurella multocida B:2 was tested in buffaloes in Sabah. Sixty buffaloes, kept grazing in the field with minimal human intervention were devided into three groups of 20 buffaloes per group. Buffaloes of group 1 were exposed intranasal to 5 ml vaccine containing 10(6) CFU/ml of live gdhA derivative P multocida B:2. Buffaloes of group 2 were not exposed to the vaccine but exposed to PBS and were allowed to commingle and graze in the same field as the buffaloes of group 1 while buffaloes of group 3 were similarly exposed to PBS and were grazing separately. Booster was on group 1, two weeks later. Twelve months after the first vaccination, three buffaloes from each group were brought into the experimental house and challenged subcutaneously with 10(9) CFU/ml of live wild-type P multocida B:2. All challenged buffaloes of groups 1 and 2 survived with only mild, transient signs while all control unvaccinated buffaloes developed severe signs of haemorrhagic septicaemia and were euthanased between 28 hours and 38 hours postchallenge with signs and lesions typical of haemorrhagic septicaemia. These data showed that the gdhA mutant strain, given intranasally as two doses two weeks apart, successfully induced systemic immunity in exposed buffaloes and also led to spread of vaccine strain to the in-contact animals, where it acted as an effective live vaccine to protect both exposed buffaloes and in-contact buffaloes against challenge with the virulent parent strain.     

Vaccination of calves with a diaminopimelic acid mutant of Salmonella typhimurium.

The purpose of this study was to evaluate the safety and efficacy of a diaminopimelic acid mutant of Salmonella typhimurium as a vaccine for calves. Transposon techniques were used to create a stable nonreverting diaminopimelic acid mutant of a virulent S. typhimurium strain. Calves were vaccinated at weekly intervals with the diaminopimelic acid mutant given as an oral dose of 10(10) organisms, followed by two subcutaneous doses of 10(9) organisms. The calves tolerated vaccination well and the vaccine strain was eliminated from the feces within four days. Of five vaccinated calves, three survived challenge with 5 X 10(9) organisms of the parent strain whereas all five unvaccinated calves that were challenged died. The surviving calves eliminated the challenge organism from the feces within three weeks.     

An evaluation in pigs of Nobi-Vac AR and an experimental atrophic rhinitis vaccine containing P multocida DNT-toxoid and B bronchiseptica

The trial involved eight large white sows obtained from a closed experimental specific pathogen free herd. Four sows (two each for an experimental vaccine and for Nobi-Vac AR) were vaccinated twice (eight weeks and two weeks before parturition) with 2 ml of vaccine administered intramuscularly. Two unvaccinated sows were used as an infected control group and two unvaccinated sows served as an uninfected control group. Forty-six piglets (28 from vaccinated sows and 18 from unvaccinated sows) were challenged by intranasal instillation of Bordetella bronchiseptica at two days of age and Pasteurella multocida type D, dermonecrotic toxin at seven days of age. Among the infected control group some piglets died and there were clinical signs of pneumonia and severe turbinate atrophy. In the vaccinated groups the results showed that immunisation of the pregnant sows had provided a good level of antibodies, which were transmitted to their offspring. There was a significant reduction in the clinical signs and no lesions were observed in the group vaccinated with the experimental vaccine and only moderate atrophy of the turbinates in the Nobi-Vac AR group. B bronchiseptica and P multocida were never recovered from the lungs of the vaccinated groups and in the nasal cavities their frequency declined with age.     

Intranasal vaccination of pigs against Aujeszky's disease: comparison with one or two doses of attenuated vaccines in pigs with high maternal antibody titres

Ten-week-old pigs with high levels of maternally derived antibody (MDA) against Aujeszky's disease virus (ADV) were given either a single intranasal vaccination or one or two doses (with an interval of three weeks) of commercially available attenuated ADV vaccines intramuscularly. The pigs did not produce a clear neutralising antibody response to ADV. However, pigs vaccinated intranasally and pigs given two doses of attenuated ADV vaccines were protected against intranasal challenge with virulent ADV two months after the first vaccination. Pigs given one parenteral dose of attenuated ADV vaccine were insufficiently protected. Protection was shown by shorter periods of growth arrest and fever and a greater reduction of virulent virus shedding after challenge in vaccinated pigs than in unvaccinated control pigs. Although intranasal vaccination conferred protection comparable to two parenteral doses of attenuated vaccines, it reduced shedding of virulent virus much more effectively. These results, together with those of other studies, show that intranasal vaccination confers better protection against Aujeszky's disease in pigs with MDA than parenteral vaccination. However, the efficacy of intranasal vaccination also decreases with increasing levels of MDA at the time of vaccination.     

Effect of maternal antibodies on induction and persistence of vaccine-induced immune responses against bovine viral diarrhea virus type II in young calves

OBJECTIVE: To determine the effect of maternally derived antibodies on induction of protective immune responses against bovine viral diarrhea virus (BVDV) type II in young calves vaccinated with a modified-live bovine viral diarrhea virus (BVDV) type I vaccine. DESIGN: Blinded controlled challenge study. ANIMALS: 24 neonatal Holstein and Holstein-cross calves that were deprived of maternal colostrum and fed pooled colostrum that contained a high concentration of (n = 6) or no (18) antibodies to BVDV. PROCEDURE: At 10 to 14 days of age, 6 seropositive and 6 seronegative calves were given a combination vaccine containing modified-live BVDV type I. All calves were kept in isolation for 4.5 months. Six calves of the remaining 12 untreated calves were vaccinated with the same combination vaccine at approximately 4 months of age. Three weeks later, all calves were challenged intranasally with a virulent BVDV type II. RESULTS: Seronegative unvaccinated calves and seropositive calves that were vaccinated at 2 weeks of age developed severe disease, and 4 calves in each of these groups required euthanasia. Seronegative calves that were vaccinated at 2 weeks or 4 months of age developed only mild or no clinical signs of disease. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicate that a single dose of a modified-live BVDV type-I vaccine given at 10 to 14 days of age can protect susceptible young calves from virulent BVDV type II infection for at least 4 months, but high concentrations of BVDV-specific maternally derived antibodies can block the induction of the response.     

Duration of the protection of an E2 subunit marker vaccine against classical swine fever after a single vaccination

The period during which pigs are protected after vaccination is important for the successful usage of a marker vaccine against classical swine fever virus (CSFV) in an eradication programme. In four animal experiments with different vaccination-challenge intervals we determined the duration of protection of an E2 subunit marker vaccine in pigs after a single vaccination. Unvaccinated pigs were included in each group to detect transmission of the challenge virus.Three groups of six pigs were vaccinated once and subsequently inoculated with the virulent CSFV strain Brescia after a vaccination-challenge interval of 3, 51/2, 6 or 13 months. All vaccinated pigs, 16 out of 18, with neutralising antibodies against CSFV at the moment of challenge, 3, 51/2, 6 or 13 months later, survived, whereas unvaccinated control pigs died from acute CSF or were killed being moribund. A proportion of the vaccinated pigs did however develop fever or cytopenia after challenge and two vaccinated pigs were viremic after challenge. Virus transmission of vaccinated and challenged pigs to unvaccinated sentinel pigs did not occur in groups of pigs which were challenged 3 or 6 months after a single vaccination. Two out of eight vaccinated pigs that were found negative for CSFV neutralising antibody at 13 months after vaccination died after subsequent challenge.The findings in this study demonstrate that pigs can be protected against a lethal challenge of CSFV for up to 13 months after a single vaccination with an E2 subunit marker vaccine.     

Experimental infections with Dictyocaulus viviparus in vaccinated and unvaccinated red deer

Four of eight red deer calves which had been artificially reared and were lungworm free were vaccinated with bovine lungworm oral vaccine when eight weeks old; the other four were not vaccinated. Three of each category were challenged daily with 500 Dictyocaulus viviparus infective stage larvae per kg liveweight for 17 days when six months old while one in each category was left as an unchallenged control. The effects of challenge were monitored and all challenged deer and one control were killed for post mortem assessment. Challenge with D viviparus was associated with reduced food intakes and weight gains but vaccinated calves were less affected than unvaccinated ones. The reaction of the alveolar tissue of red deer lung to D viviparus was mild in vaccinated and unvaccinated animals and differed from that of bovine lung in that alveolar epithelialisation was limited and hyaline membrane formation and interstitial emphysema were not seen. The disease was most evident in and around airways and was less in vaccinated calves. It was concluded that young red deer are tolerant to D viviparus but will readily acquire infection.     

Mycoplasma gallisepticum vaccination: effects on egg transmission and egg production

The effects of Mycoplasma gallisepticum (MG) vaccination on egg transmission of MG and egg production were evaluated. Leghorn hens vaccinated with live MG (strain F), with strain F plus MG bacterin, with one dose of MG bacterin, or with two doses of MG bacterin all transmitted MG through the egg at a significantly lower level than unvaccinated controls. Hens vaccinated with two doses of MG bacterin had the longest lag before detectable transmission of MG through the egg. All vaccinated groups were protected against the egg-production drop seen in unvaccinated hens challenged with virulent MG.     

Intranasal vaccination of pigs against Aujeszky's disease: protective immunity at 2 weeks, 2 months and 4 months after vaccination in pigs with maternal antibodies.

The purpose of the study was to evaluate the short- and long-term immunity after intranasal vaccination in pigs with maternally derived antibodies (MDA). In two experiments, 10-week-old pigs with moderate MDA titres against Aujeszky's disease virus (ADV) were vaccinated intranasally with the Bartha strain of ADV to evaluate the protective immunity conferred at 2 weeks, 2 months and 4 months after vaccination. Protection was evaluated on the basis of severity of clinical signs, periods of fever and growth arrest, and duration and amount of virus excreted after challenge with a virulent ADV. During the first 2-3 weeks after vaccination, antibodies to ADV continued to decline as in unvaccinated control pigs. After that, antibody titres stabilized or gradually increased. At 2 weeks, 2 months and 4 months after vaccination, vaccinated pigs were significantly better protected than unvaccinated controls. The vaccinated pigs challenged 2 weeks after vaccination hardly developed any sign of disease. Mild signs of Aujeszky's disease and a growth arrest period of 5 days were observed in vaccinated pigs challenged 2 months after vaccination, whereas vaccinated pigs challenged 4 months after vaccination developed severe signs of disease and a growth arrest period of 13 days. Vaccinated pigs challenged 2 weeks after vaccination did not excrete challenge virus, and pigs challenged 2 or 4 months after vaccination excreted far less virus than unvaccinated controls. The results demonstrate that intranasal ADV vaccination of pigs with moderate MDA titres protected them from 2 weeks to at least 4 months after vaccination. Immunity steadily declined, however, after vaccination.     

Immunization against bovine herpesvirus-1 infection. Preliminary tests in calves with a DNA vaccine

A bovine herpesvirus-1 (BHV-1) vaccine expressing glycoprotein D, the form with the transmembrane anchor removed, was evaluated for inducing immunity in calves. The plasmid encoding gD of BHV-1 was injected three times to nine calves, using three animals for each of the following routes: intramuscularly (i.m.), intradermally (i.d.), or intranasally (i.n.). Three additional calves were given the plasmid vector only and served as unvaccinated controls. When calves were subjected to challenge infection with BHV-1, all vaccinated calves as well as the controls developed a typical severe form of infectious bovine rhinotracheitis. However, compared to the controls, the vaccinated calves showed earlier clearance of challenge virus. Moreover, the calves given the vaccine i.m. developed neutralizing antibody to BHV-1 between 21 and 42 days following the first injection of vaccine, whereas in calves vaccinated either i.d. or i.n., as well as the controls, antibody first appeared in their sera 14 days post-challenge infection.     

Evaluation of efficacy of an inactivated vaccine against bovine respiratory syncytial virus in calves with maternal antibodies

OBJECTIVE: To assess short- and long-term efficacy of an inactivated bovine respiratory syncytial virus (BRSV) vaccine administered i.m. to calves with maternally derived antibodies. ANIMALS: 28 two-week-old calves with neutralizing, maternally derived antibodies against BRSV. PROCEDURE: For evaluation of short-term efficacy, 6 calves were vaccinated i.m. at 2 and 6 weeks of age and challenged intranasally and intratracheally along with a matched group of 4 unvaccinated control calves at 10 weeks of age. For evaluation of long-term efficacy, 2 groups of 6 calves each were vaccinated i.m. at 2, 6, and 18 weeks of age or 14 and 18 weeks of age; these calves were challenged intranasally and intratracheally along with 6 matched unvaccinated control calves at 43 weeks of age. Serum virus neutralizing antibody titer, clinical reactions, and virus shedding in nasal mucus and lung washings were assessed. RESULTS: None of the vaccination regimens resulted in a significant increase in serum virus neutralizing antibody titer. As judged by virus shedding in nasal mucus and lung washings, vaccinated calves were protected against challenge, compared with unvaccinated control groups. Clinical signs attributable to challenge were coughing (short-term efficacy study) and tachypnea and dyspnea (long-term efficacy study). The severity and incidence of disease were significantly lower in the vaccinated groups, compared with that in the unvaccinated groups. CONCLUSIONS AND CLINICAL RELEVANCE: Through vaccination, it is possible to protect vulnerable calves with maternal antibodies against BRSV infection and reduce respiratory tract disease.     

Pasteurella multocida infection in the domestic rabbit: immunization with a streptomycin-dependent mutant.

Fourteen Pasteurella multocida-free rabbits were inoculated intranasally with a streptomycin-dependent mutant of P. multocida serotype 12:A. Vaccinations with approximately 10(8) colony forming units were done on days 0, 14 and 28. Two weeks later the animals were separated into groups, which included 12 rabbits divided into two control groups of six unvaccinated Pasteurella-free animals. Seven vaccinated rabbits were challenged intranasally with the homologous virulent parent strain and the other seven vaccinates were challenged with a virulent strain of serotype 3:A. Rabbits were necropsied two weeks later. The vaccinated group challenged with the parent strain showed a more rapid nasal clearance of the organism than the vaccinated group challenged with the heterologous strain. However, the number of positive cultures of P. multocida recovered from tissues post-challenge were similar in vaccinated and control animals. In a significant number of animals, vaccination with serotype 12:A induced detectable antibody production to somatic antigens of both 12:A and heterologous strain 3:A.     

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.