Ornithobacterium rhinotracheale infection in turkeys: immunoprophylaxis studies

Ornithobacterium rhinotracheale has been shown to cause serious clinical illness and is a significant concern to the turkey industry because of its potential economic impact. In this study, 6-wk-old turkeys were vaccinated intranasally with a live or subcutaneously with a killed O. rhinotracheale vaccine. At 14 or 21 wk of age, the birds were challenged intratracheally with live O. rhinotracheale. Airsacculitis and pneumonia occurred less frequently in vaccinated birds than in unvaccinated birds after challenge with O. rhinotracheale. Ornithobacterium rhinotracheale was recovered from unvaccinated, challenged birds but not from vaccinated, challenged or from unchallenged birds. Thus, turkeys inoculated with live or killed O. rhinotracheale vaccine were protected from pathologic changes.     

Immunogenicity of an oil-emulsified Escherichia coli bacterin against heterologous challenge

Immunogenicity of an oil-emulsified Escherichia coli bacterin against heterologous challenge was investigated. In Expts. 1 and 2, chickens were vaccinated with E. coli serotype O1 bacterin and challenged with E. coli serotype O2 (Expt. 1) and O78 (Expt. 2). Positive control chickens were not vaccinated but challenged with E. coli serotype O2 or O78; unvaccinated unchallenged chickens served as negative controls. When challenged with E. coli serotype O2, unvaccinated chickens showed a higher morbidity than vaccinated chickens. There was no mortality in either group. Although average gross lesion scores were generally higher in the unvaccinated chickens, they were not significantly different (P greater than or equal to 0.05) from those in the vaccinated chickens. In Expt. 2, morbidity was slightly higher in the unvaccinated challenged chickens. No mortality occurred in either group. There was no significant difference (P greater than or equal to 0.05) between vaccinated and unvaccinated chickens in average gross lesion scores. In general, E. coli recovery was higher in the unvaccinated challenged chickens, being highest in the air sacs followed by the liver, heart blood, and pericardial sacs. There was no morbidity, mortality, or gross lesions in the unvaccinated unchallenged chickens. No E. coli was recovered from the tissues cultured. The results of these laboratory trials revealed that an oilemulsified monovalent E. coli bacterin did not protect chickens against other E. coli serotypes associated with colibacillosis.     

Efficacy of a type 2 PRRSV modified live vaccine (PrimePac™ PRRS) against a Thai HP-PRRSV challenge

The Chinese highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV) has caused a severe threat to the pig population in Southeast Asian countries. The purpose of this study was to investigate the efficacy of a type 2 PRRSV modified live vaccine (PrimePac? PRRS, lineage 7) against a Thai HP-PRRSV (10PL01, lineage 8). Three-week-old PRRSV-free pigs were randomly assigned into three groups. Vaccinated challenged group (group 1, n?=?16) was immunized with PrimePac? PRRS vaccine at 3 weeks old. The unvaccinated challenged group (group 2, n?=?16) was injected with PBS at 3 weeks old, and unvaccinated unchallenged group (group 3, n?=?10) was served as a negative control. At 9 weeks old, all groups, except the negative control group, were challenged with the Thai HP-PRRSV. All pigs were monitored daily during 10 days post-infection (dpi) and were necropsied at 10 and 17 dpi. The results revealed that vaccinated challenged pigs showed significantly lower (p?<?0.05) mean rectal temperatures, clinical respiratory scores, lung lesion scores, and levels of virus load in serum and lung tissue compared with the unvaccinated challenged pigs. Moreover, vaccinated challenged pigs exhibited PRRSV-specific serum neutralizing antibodies at the end of the experiment. Our findings indicated that the studied type 2 PRRSV vaccine provided partial protection against the Thai HP-PRRSV infection based on the body temperature, levels of viremia, and the severity of lung lesions. These results demonstrated that partial protection of PrimePac? PRRS vaccine might be useful for controlling HP-PRRSV infection in the endemic area.     

The efficacy of a temperature-sensitive mutant vaccine against Northwest Arkansas isolates of Alcaligenes faecalis

The efficacy of a commercially produced temperature-sensitive mutant Alcaligenes faecalis vaccine was evaluated in turkeys contact-challenged with one of three strains of A. faecalis. In the vaccinated control group, the vaccine strain of A. faecalis colonized the nasal turbinates but not the trachea, caused no clinical signs of turkey coryza, and induced humoral antibodies. In the vaccinated challenged groups, the vaccine reduced both the severity of lesions and the number of birds exhibiting lesions compared with unvaccinated challenged groups, but it did not prevent colonization of challenge strains of A. faecalis.     

Vaccination against infectious bronchitis in young chickens--carriers or not of maternal antibodies

The immunity to infectious bronchitis afforded by spray vaccination of mycoplasma free two days-old broilers with maternal antibodies to infectious bronchitis virus was tested by comparing zootechnical scores, clinical signs, macroscopical and microscopical changes, frequency of infectious bronchitis virus isolation following challenge at one, three and five weeks of age in vaccinated, unvaccinated, challenged and unchallenged birds. This vaccination gave a very good protection to infectious bronchitis for the most part of broiler economical life; growth delays were especially avoided. However, vaccinated and unvaccinated one-week-old birds were not protected enough. No correlation was observed between haemagglutinating antibodies titres and protection. At last this vaccination caused a notable reaction in specific pathogen free control birds of the same age.     

Immunization of turkeys with a DNA vaccine expressing either the F or N gene of avian metapneumovirus

In this study we compared protection by DNA vaccination with the F (pCMV-F) or N (pCMV-N) gene from avian metapneumovirus (aMPV) in turkeys. One-week-old turkey poults received two intramuscular injections 2 wk apart. Birds were challenged with a turkey-embryo-adapted aMPV at 5 wk of age. Birds vaccinated with pCMV-F had decreased clinical signs of disease as well as significantly reduced virus load in tracheal swabs compared with birds vaccinated with pCMV-N or unvaccinated control birds. Serum neutralizing antibodies were significantly higher in birds receiving pCMV-F compared with all other groups. These results indicate that DNA vaccination with the F, but not N, gene of aMPV can induce significant protection against aMPV infection.     

The live attenuated bovine viral diarrhea virus components of a multi-valent vaccine confer protection against fetal infection

Fetal infection with bovine virus diarrhea virus (BVDV) causes severe economic loss and virus spread in cattle. This study investigated the ability of modified live BVDV I and II components of a commercially available modified live virus (MLV) vaccine (Breed-Back FP 10, Boehringer Ingelheim Vetmedica Inc.) to prevent fetal infection and abortion, and therefore the birth of persistently infected animals. Heifers immunized with vaccine 4-8 weeks before insemination showed no adverse effects. All vaccinated animals had seroconverted to BVDV 4 weeks after immunization. Pregnant heifers were divided into two vaccination and two control groups and challenged with type I or II BVDV on days 60-90 of gestation. Seroconversion, clinical signs, immunosuppression, viremia, mortality, abortion rate, and fetal infection were studied. Post-challenge, 6/11 (type I challenged) and 8/11 (type II challenged) vaccinated heifers were free from clinical signs of BVD. Post-challenge clinical signs noted in the vaccinated groups were mild to moderate, while all unvaccinated controls had clinical signs ranging from moderate to severe. Viremia was not detected post-challenge in any of the vaccinated heifers. However, 100% of the controls were BVDV viremic on at least 1 day post-challenge. One of 22 vaccinated heifers had transient leukopenia, whereas 2/8 and 6/7 unvaccinated heifers in control groups I and II, respectively, had transient leukopenia. Type II BVDV infection led to abortion or death in 86% of unvaccinated heifers. The corresponding vaccinated group showed no deaths or abortions. All control group fetuses were infected with BVDV. The test vaccine gave 91% (type I BVDV challenged) and 100% (type II BVDV challenged) protection from fetal infection. This vaccine is safe and effective against fetal infection, abortion (type II BVDV) and the birth of persistently infected animals.     

The effects of caseous lymphadenitis on wool production and bodyweight in young sheep

Two hundred Merino wether hoggets were used to examine the effect of Corynebacterium pseudotuberculosis infection (caseous lymphadenitis) on wool production and bodyweight. Sheep which were challenged with C. pseudotuberculosis (artificially infected) and not vaccinated against this disease produced 0.20 kg less clean wool than unchallenged controls during the following 12 months. The incidence of sheep with lesions in the group that was vaccinated prior to challenge was 55% lower than in unvaccinated challenged sheep but their wool production was not significantly different from either the controls or the unvaccinated challenged sheep. Vaccinated sheep were also heavier than unvaccinated sheep 12 months after challenge. These results indicate that caseous lymphadenitis infection may reduce wool production.     

Response of domestic geese to lentogenic and velogenic strains of Newcastle disease virus

A total of 54 domestic white meat-type geese were included in vaccination/challenge trials to evaluate susceptibility to disease and humoral immune responses using the haemagglutination inhibition (HI) and virus neutralization (VN) tests against Newcastle disease (ND). Two groups of twenty geese, five weeks of age, were conjunctivally vaccinated with either 100 x 10(6) or 2.5 x 10(6) EID50 (egg infectious dose 50 per cent) per bird of live La Sota virus, respectively, and 14 geese remained unvaccinated. At 15 weeks of age all vaccinated geese and seven unvaccinated geese were subcutaneously injected with 0.5 ml of inactivated oil emulsion ND vaccine, whereas seven geese remained as negative controls. At an age of 20 weeks, all 54 geese were challenged with 10(8.0) EID50 per bird of the viscerotropic velogenic NDV strain Herts 33/56. Live virus application as well as the oil emulsion vaccine did not induce discernible clinical signs and have no detrimental effect on body weight gains. At days 1, 3, 5, 8, 13, 16, 20, 23 and 27 after the application of lentogenic vaccine pharyngeal and cloacal swabs were taken, after challenge samples were taken at days 2, 5 and 8. Lentogenic as well as velogenic virus were never reisolated. Low and shortlived antibody responses post vaccination were equally well measured in HI and VN tests. Only two out of seven unvaccinated but challenged geese developed signs of ND whereas all vaccinated/challenged geese remained normal but developed high to moderate levels of HI and VN antibodies. Since domestic geese do not readily excrete NDV's in detectable amounts and since they do not contain detectable amounts of the challenge virus fourteen days post challenge in their tissues the assumption is promoted that geese do not play a major role in the epidemiology of Newcastle disease.     

Trial of a novel experimental Toxoplasma iscom vaccine in pregnant sheep

Fifteen vaccinated ewes (group 1) and 13 unvaccinated ewes (group 2) were each challenged orally with 2000 sporulated Toxoplasma gondii oocysts at 91 (+/- 1) days' gestation. Another four pregnant ewes acted as unvaccinated unchallenged controls. Lamb mortality in group 1 was 36.4% after a mean gestation of 141 days while in group 2 it was 64.7% after a mean gestation of 131.5 days. These differences were not statistically significant. However, substantially more specific antibody was detected in precolostral sera from live lambs from vaccinated ewes than in live lambs from unvaccinated ewes in group 2.     

马立克氏病胚胎免疫雏鸡体重和免疫器官增重变化

１８日龄鸡胚免疫接种火鸡疱疹病毒（ＨＶＴ）疫苗后,对出壳后雏鸡及其用马立克氏病（ＭＤ）病毒攻毒鸡体重与免疫器官增长效果的对比研究表明：相同饲养条件下胚胎免疫雏鸡的增长速度高于非免疫对照鸡,而且胚胎免疫组雏鸡免疫器官的生长发育普遍较相应的对照组雏鸡快。     

Partial protection against tissue cysts formation in pigs vaccinated with crude rhoptry proteins of Toxoplasma gondii

A vaccine containing crude Toxoplasma gondii rhoptry proteins incorporated in the immunostimulating complexes (ISCOM) adjuvant was tested in pigs for protecting against tissue cyst formation. For this, 38 mixed breed pigs were divided into four groups, G1 (vaccinated challenged, n=10) received two doses (100 microg/dose) of the rhoptry vaccine at days 0 and 21, G2 (vaccinated challenged, n=10) received viable tachyzoites (7 x 10(7)) of the RH strain at day 0, G3 (unvaccinated challenged, n=10) and G4 (unvaccinated unchallenged, n=8). Pigs were challenged with 4 x 10(4) VEG strain oocysts 57 days later. The G1 pigs produced high IgG antibody levels in the indirect enzyme-linked immunosorbent assay (ELISA) after the second dose of rhoptry vaccine, but were not clinically protected against a high dose oocyst challenge. Partial protection was observed in G1 at the chronic phase of infection, when compared with G3. Pigs in group 2 developed high antibody levels and were protected against clinic signs. T. gondii was not detected in two (G1) and three (G2) pigs by mouse bioassay. The results indicate partial protection in pigs vaccinated with a rhoptry vaccine.     

Effects of differences in virulence of different serovars of Haemophilus paragallinarum on perceived vaccine efficacy

The virulence of four South African field isolates of NAD-dependent Haemophilus paragallinarum and two field isolates of NAD-independent H. paragallinarum has previously been tested in unvaccinated chickens. In this study, the disease profiles caused by the NAD-dependent isolates of H. paragallinarum in vaccinated chickens were studied. It was shown that the clinical signs induced in the vaccinated chickens were substantially less severe than were those in unvaccinated chickens, as was expected. However, due to the high virulence of the serovar C-3 isolates, clinical signs in the vaccinated chickens challenged with this isolate were still detected. These were as severe as those occurring in unvaccinated chickens challenged with serovar B-1 isolates. Although the clinical signs induced in unvaccinated birds challenged with serovar A-1 were more severe than those occurring when vaccinated birds were challenged with serovar C-3, the overall disease profiles were similar. Substantial clinical signs were recorded in vaccinated birds challenged with serovar C-3. This could be interpreted as vaccination failure if the disease profile obtained in unvaccinated birds is not considered. It was found that a high level of protection was provided by this vaccine against challenge by serovar C-3. The high virulence of this serovar resulted in the development of clinical signs in vaccinated birds. These findings could possibly explain the large number of so-called vaccination failures that are reported in South Africa.     

Effects of adjuvant-augmented germling vaccines in turkey poults challenged with Aspergillus fumigatus

Turkey poults were vaccinated with combinations of two different germling preparations and three adjuvants (N-acetylmuranyl-L-alanyl-D-isoglutamine, Pasteurella multocida lipopolysaccharide [LPS], and avridine) at 1 and 2 weeks of age, and their immunity was challenged by sublethal exposure to aerosols of Aspergillus fumigatus conidia at 1 month of age. Fewer turkeys in the groups given vaccines prepared from germlings grown on Dorset's and Henley's medium (D&H) had organisms in lung tissue at 2 weeks after challenge exposure as compared with those vaccinated with germling grown on neopeptone dialysate (Neo). The LPS of P. multocida appeared to be the most efficacious of the adjuvants in the D&H vaccine group, as A. fumigatus was isolated from only one of eight turkeys in this group; the number of organisms per gram of lung tissue was low compared with other vaccine groups at 2 weeks after challenge exposure; and poults given D&H vaccine with LPS as adjuvant had less-severe lung lesions than other groups. These differences in lung lesions were more marked at 2 weeks than at 8 weeks after challenge exposure. The only difference among other parameters in the vaccinated turkeys was lower heterophil counts in the turkeys given D&H-prepared vaccines than in unvaccinated controls. This was probably due to less-severe infections resulting from protective effects of these vaccines.     

Efficacy of viable and inactivated Newcastle disease virus vaccines in turkeys

Market turkeys spray-vaccinated at 20 days of age with viable Newcastle disease virus (NDV) vaccine and challenged 7 weeks postvaccination failed to yield NDV by tracheal swabbing 4 days postchallenge but demonstrated serologic evidence of infection. Birds vaccinated subcutaneously with inactivated oil-emulsion (OE) NDV vaccine had virologic and serologic evidence of infection. Breeder hens vaccinated by spray with commercial La Sota vaccine at 19 weeks of age and revaccinated subcutaneously with OE vaccine at 32 weeks of age had an adequate level of resistance against a drop in egg production but demonstrated serologic evidence of infection when challenged with velogenic NDV at 38 weeks of age.     

Cold-adapted strain of avian pneumovirus as a vaccine in one-day-old turkeys and the effect of inoculation routes

To determine the optimum route of vaccination, we inoculated 1-day-old turkeys with a cold-adapted strain of avian pneumovirus (APV) by oculonasal, oral, or aerosol route. Another two groups served as nonvaccinated-challenged and nonvaccinated-nonchallenged groups. Birds in all vaccinated and nonvaccinated-challenged groups were challenged with virulent APV 3 wk postvaccination. After challenge, no vaccinated bird developed clinical signs or virus shedding, whereas nonvaccinated-challenged birds developed clinical signs (clinical score = 11.2/bird) and shed virus from their choanal cleft. Birds in all three vaccinated groups seroconverted at 3 wk postvaccination. The nonvaccinated-nonchallenged group remained free of clinical signs and virus shedding and did not develop APV antibodies throughout the course of the study. These results suggest that this cold-adapted strain of APV is safe and effective in 1-day-old turkeys when given by any of the three routes.     

Study of infection with an Iranian field-isolated H9N2 avian influenza virus in vaccinated and unvaccinated Japanese quail

In the present study, we examined the mortality rate, egg production, and clinical signs of quail experimentally infected with a field isolate of A/Chicken/Iran/339/02 (H9N2) avian influenza virus obtained from an infected commercial layer farm with severe morbidity and mortality. A total of 120 quail at 14 days old were randomly divided into four groups of vaccinated (B and C) and unvaccinated (A and D) birds. Vaccination was done on days 20 and 32, and viral inoculation of birds in groups C and D was then carried out on day 43. For evaluation of viral transmission, at 24 hr postinoculation additional unvaccinated birds were placed in direct contact with challenged birds. All the birds were evaluated for clinical signs, egg production, antibody production, viral titration in lung homogenates, and viral transmission following inoculation. All unvaccinated-challenged birds were infected and showed clinical signs, whereas the infection rate along with clinical signs of vaccinated-challenged birds reached 30%-40%. Although vaccination induced high antibody titers, reduction in food and water consumption was evident in this vaccinated-challenged group compared with the unchallenged control group. These results could indicate that inactivated vaccine did not fully prevent the infection, although it was capable of protecting birds against clinical signs and significantly decreased viral titers in lungs after intranasal challenge.     

Efficacy in turkeys of spray vaccination with a temperature-sensitive mutant of Bordetella avium (Art Vax)

Broad-breasted white turkeys were vaccinated with a temperature-sensitive mutant of Bordetella avium (Art Vax) at 2 and 15 days of age and challenged at 22 days of age by contact with infected birds. Necropsy was performed at 35 days of age. Two vaccination protocols (eyedrop/oral and spray cabinet/spray bottle) and two challenge isolates (Arkansas 105 and North Carolina [NC] isolates) were used. Neither the spray nor the eyedrop/oral methods of vaccination prevented infection of the anterior trachea with either of the virulent challenge strains. The spray and eyedrop/oral methods of vaccination were equally effective in reducing the severity of gross lesions in the trachea. The vaccine reduced the severity of gross lesions in the tracheas of turkeys challenged with the NC isolate to a level approximately equal to that observed in unchallenged vaccinated controls, but the vaccine only moderately reduced the severity of lesions in birds challenged with the 105 isolate.     

Protective efficacy of commercial inactivated Newcastle disease virus vaccines in chickens against a recent Korean epizootic strain

Despite the intensive vaccination policy that has been put in place to control Newcastle disease virus (NDV), the recent emergence of NDV genotype VII strains in Korea has led to significant economic losses in the poultry industry. We assessed the ability of inactivated, oil-emulsion vaccines derived from La Sota or Ulster 2C NDV strains to protect chickens from challenge with Kr-005/00, which is a recently isolated Korean epizootic genotype VII strain. Six-week-old SPF chickens were vaccinated once and challenged three weeks later via the eye drop/intranasal route. All vaccinated birds were fully protected from disease, regardless of the vaccine strains used. All vaccinated and challenged groups showed significant sero-conversion 14 days after challenge. However, some vaccinated birds, despite being protected from disease, shed the challenge virus from their oro-pharynx and cloaca, albeit at significantly lower titers than the unvaccinated challenged control birds. The virological, serological, and epidemiological significance of our observations with regard to NDV disease eradication is discussed.     

Field vaccination against hemorrhagic enteritis of turkeys by a cell-culture live-virus vaccine

A cell-culture-propagated (CC) live-virus hemorrhagic enteritis (HE) vaccine was evaluated for efficacy and safety in two field trials conducted in North Carolina (NC) and Minnesota (MN). At 4 or 5 1/2 weeks of age, 9,839 poults in NC and 15,857 poults in MN were vaccinated with a CC HE vaccine administered via the drinking water. A comparable number of poults were maintained as unvaccinated controls. Vaccinated and unvaccinated poults were compared for seroconversion, response to laboratory challenge with a virulent HE virus at 3 weeks postvaccination, livability, percentage graded A, and average weight at marketing. In both trials, vaccination with the CC HE vaccine resulted in immunity against HE as indicated by seroconversion and by resistance to HE lesions following laboratory challenge with virulent HE virus. Compared with unvaccinated groups, vaccinated groups had a significantly higher percentage of turkeys graded A in the NC trial and in two of three flocks in the MN trial (P less than 0.005). Further, in the NC trial, livability was significantly higher (P less than 0.005) in vaccinated turkeys than in unvaccinated turkeys. These data indicate that the CC HE vaccine is efficacious and safe to use in the field.