重组禽流感灭活苗和禽流感灭活苗对鸡免疫效果的观察

用重组禽流感灭活苗接种10日龄、14日龄和21日龄的SPF鸡,接种后HI抗体效价无显著差异。将H5N1和H5N2疫苗分别接种21日龄SPF鸡,结果表明,H5N1和H5N2均能刺激SPF鸡产生较高的HI抗体;分别接种三黄鸡,接种后21 d,H5N1能刺激三黄鸡产生较高的HI抗体;而H5N2不能刺激三黄鸡产生合格的HI抗体,与SPF鸡免疫组相比差异显著。经过二次接种,HI抗体平均为8.9 log2,与SPF鸡组接种后42 d的各组相比差异不显著,而与一免后21 d的各组HI抗体效价相比差异显著。表明应用禽流感灭活苗对三黄鸡免疫接种,必须进行二免方可达到理想免疫效果,而应用重组禽流感灭活苗对三黄鸡进行免疫接种,一次免疫即可获得较高的HI抗体效价。     

Evaluation of a bovine virus diarrhea vaccine.

Singer Strain bovine virus diarrhea (BVD) modified live-virus vaccine, produced in a continuous bovine cell line using equine serum in the growth medium, evoked a high level of serum antibodies and protected against virulent challenge in vaccinated calves. Transmission of vaccinal virus from vaccinated cattle to susceptible controls did not occur when vaccinated and nonvaccinated cattle were kept in constant contact for 23 days. Postvaccinal reactions to the viral vaccine were not observed in vaccinated cattle from 10 feedlots or in cattle vaccinated with multiple doses of the experimental vaccine.     

Effects of porcine reproductive and respiratory syndrome vaccination in breeding-age animals

Little is known about the safety and efficacy of extra-label use of the modified live porcine reproductive-and-respiratory syndrome (PRRS) virus vaccine in gestating sows. Our purpose was to determine the impact of vaccination on reproductive performance in 54 herds in Ontario, Manitoba (Canada) and the mid-western United States that were PRRS-positive, PRRS-negative, or concurrently affected by an outbreak of PRRS when initially vaccinated. Majority-vaccinated herds vaccinated ≥50% but <100% of sows at one time, and limit-vaccinated herds vaccinated <50% of sows at one time. Most majority-vaccinated herds did not vaccinate sows in late gestation, and none vaccinated during the initial PRRS outbreak. Numbers of pigs born alive and weaned decreased when pregnant sows were vaccinated. The effect of vaccination on productivity in the gestation following vaccination depended on the vaccination protocol.     

Vaccination of turkey breeder hens and toms for fowl cholera with CU strain

Unvaccinated laying breeder hens and semen-producing toms were susceptible to the CU strain of Pasteurella multocida and highly susceptible to a virulent strain of P. multocida. Laying breeders vaccinated with CU strain when environmental temperatures were low ceased egg production during the first week after vaccination and had 29% mortality, whereas those vaccinated when temperatures were moderate had only a 25% decrease in egg production and 17% mortality. Comparable nonlaying breeders vaccinated during moderate temperatures did not die. Although few semen-producing toms died postvaccination and the quantity and quality of semen was not affected, 21.7% developed torticollis. Laying breeders were protected against CU vaccine and challenge with virulent P. multocida if vaccinated every 4 weeks beginning when 7 weeks old. Potential breeders vaccinated before laying with combinations of 3 vaccinations via drinking water, wing-web puncture, or inoculation into the air spaces of the head through the auditory tube were protected against challenge after the onset of laying. However, vaccination via wing-web puncture at 25 weeks of age resulted in abscesses that failed to resolve. The combination of vaccinations most effective in protecting laying breeders was vaccination in the drinking water at 7 and 11 weeks and inoculation into the air spaces of the head at 15 weeks.     

Maternal antibody passively transferred interferes with rabies vaccination in hamsters

Transference and interference of maternal immunity to offspring after rabies vaccination were studied in hamsters. Females were vaccinated or not before mating and offspring were vaccinated at the age of 7, 14, 21 and 30 days. Other pups were maintained as controls. Thirty days after vaccination pups were challenged intracerebrally with CVS virus. Mouse neutralization tests were used to verify antibody titers. Mortality of 97.0, 76.9, 60.9 and 24.0% was observed in pups vaccinated at 7, 14, 21 and 30 days respectively, born from vaccinated dams, while in pups from non-vaccinated dams, mortality was 51.4, 28.6, 8.7 and 0.0%. Statistically significant associations were found between mortality and age at vaccination, by simple linear regression with y=-3.1169x + 120.8 (p = 0.008; r2=0.98) for litters vaccinated and born from vaccinated dams and y=-2.2541x + 62.7495 (p = 0.03; r2=0.93) for pups vaccinated and born from non-vaccinated dams. Immunological response to vaccination in pups born from vaccinated mothers was delayed 11 days, when compared to that observed in pups of non-vaccinated mothers.     

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.     

Effect of vaccination with live or killed Pasteurella haemolytica on resistance to experimental bovine pneumonic pasteurellosis

Using 6- to 8-month-old beef calves, 3 experiments were conducted to compare the effect of vaccination with live or killed Pasteurella haemolytica on resistance to a transthoracic challenge exposure with the organism and to correlate serum antibody response with resistance. In each experiment, calves were vaccinated twice at 1-week intervals and were challenge exposed 21 days after the first inoculation. Lung lesions were evaluated by a system, such that higher scores indicated the more severe lesions. In each experiment, calves immunized with live P haemolytica had lower lesion scores than calves vaccinated with saline solution or bacterin. In 2 of the experiments, the differences were significant (P less than 0.05). In all experiments, calves vaccinated parenterally with a commercial P haemolytica/P multocida bacterin or with a formalin-killed P haemolytica bacterin had lesion scores that were not significantly different (P greater than 0.05) than for control calves vaccinated with saline solution. Live and killed bacterial preparations induced a significant serum antibody response to P haemolytica as measured by a quantitative fluorometric immunoassay. The antibody response to vaccination was not affected by preexisting titers to P haemolytica. Serum antibody titers were not consistently as high for calves vaccinated with bacterins as for calves vaccinated with live organisms. Although high antibody titers correlated with low lesion scores when calves vaccinated with saline solution or live organisms were analyzed collectively, there was not a significant correlation between the 2 variables when calves, vaccinated with saline solution or with bacterin, were analyzed collectively. These data indicate that, although bacterins may induce a detectable serum antibody response, they do not induce protection against transthoracic challenge exposure to P haemolytica.     

The reproductive performance of sows after PRRS vaccination depends on stage of gestation

In order to minimize the effects of porcine reproductive and respiratory syndrome (PRRS) on stillbirth, mummification, and neonatal mortality in swine herds, many producers have vaccinated their herds using a modified-live virus vaccine. The purpose of this study was to determine the association of the PRRS modified-live vaccine and reproductive performance by stage of gestation when the vaccine was administered. A total of 47 swine herds from Ontario and Manitoba, Canada, and from the mid-western USA were included in the study. Participating farms had vaccinated all of their sows at one point in time when they used the vaccine for the first time. The reproductive performance of sows that farrowed in the year prior to use of the vaccine was compared to that of sows vaccinated in each of five stages of gestation and in the gestation that followed the initial use of the vaccine. Sows vaccinated at any time during gestation had a reduced number of pigs born alive, a reduced number of pigs weaned per litter, and increased number of stillborn pigs and an increased number of mummified pigs compared to the sows that farrowed prior to use of the vaccine. The largest association was seen in sows that were vaccinated in the last four weeks of gestation. The largest losses were observed in those herds that were vaccinated concurrently with the initial PRRS herd outbreak. These results suggest that the modified-live vaccine should only be administered to non-gestating sows.     

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.     

Evaluation of an atrophic rhinitis vaccine under controlled conditions.

A vaccine containing inactivated cultures of Bordetella bronchiseptica, toxigenic Pasteurella multocida type D and dermonecrotic P multocida type D toxoid in an oil-in-water adjuvant was given to seven sows, with seven others acting as controls. Half the piglets in each litter were exposed intranasally when four days old to B bronchiseptica and when eight days old to toxigenic P multocida type D. There was considerably less sneezing in the litters of the vaccinated sows and when the piglets were 10 weeks old, only 18 per cent had deformed snouts compared with 74 per cent in the litters of the control sows. The average liveweight gain of the piglets born to vaccinated sows was significantly better (P less than 0.05) between two and 10 weeks of age than that of the piglets born to unvaccinated sows, although there were no significant lower respiratory tract lesions in either group. The conchal atrophy scores were significantly lower (P less than 0.001) in the piglets from the vaccinated sows and were negatively correlated (r = -0.37) with increasing liveweight gain. In the liters of the vaccinated sows, P multocida was not isolated from the nasal passages of the in-contact piglets and from only 7 per cent of those deliberately exposed compared with 65 per cent and 79 per cent, respectively, in the litters of the control sows. P multocida was isolated post mortem from the tonsils of 23 per cent of the piglets of vaccinated sows and from 87 per cent of those from unvaccinated sows.     

Infectious bovine keratoconjunctivitis: evidence for genetic modulation of resistance in purebred Hereford cattle

A vaccination study was conducted in a herd of purebred Hereford cattle representing 4 selection (genetic) lines. For each of 2 years, half of the cattle were vaccinated with a pilus-enriched Moraxella bovis bacterin. Cows were vaccinated before parturition, and calves were vaccinated at 2 to 3 months of age. None of the cattle was vaccinated for 1 year preceding and 1 year after the 2 years in which cattle were vaccinated. There was a significantly (P less than 0.05) lower percentage of infectious bovine keratoconjunctivitis (IBK) in calves during years cattle were vaccinated than during years cattle were not vaccinated. During years cattle were vaccinated, there were lower percentages of IBK in vaccinated calves when compared with the percentages of IBK in nonvaccinated calves. When calves were compared on the basis of selection lines, regardless of the vaccination group, there were consistent differences in the percentages that developed IBK. Although calves with pigmented and nonpigmented eyes (representing all 4 genetic lines) developed IBK, the genetic line of calves with the most pigmented eyes had the lowest (P less than 0.05) percentage of IBK. Also, across all genetic lines, there was less IBK in pigmented eyes than in nonpigmented eyes. Seemingly, vaccination of dams, before parturition, and young calves reduced the occurrence of severe IBK in a herd situation under natural exposure conditions. The resistance or susceptibility in cattle under good management may be influenced by genetic factors.     

Vaccination of dairy calves with bovine adenovirus type 3

A field study was undertaken to determine the efficacy of vaccinating dairy calves with a killed bovine adenovirus type 3 (BA3) vaccine in a herd where pneumonia associated with BA3 infection had been a severe problem. Calves were first vaccinated when they were less than one week old; a second dose was given 10-14 days later. Efficacy of the vaccine was evaluated following natural exposure to the virus by comparing prevalence of pneumonia in control (n = 21) and vaccinated (n = 21) calves. Seroconversion to BA3 was shown in 9 of 12 control calves that developed pneumonia, 4 of these calves subsequently died as a result of the disease. Four additional control calves had a subclinical infection with the virus. All calves in the vaccinated group developed virus-neutralizing antibodies which averaged 1:20 eight weeks after the second vaccination. The serologic response to vaccination was not inhibited in calves possessing low levels of colostral antibodies. Two vaccinated calves developed pneumonia but they did not succumb to the disease. The prevalence of pneumonia in vaccinated calves was significantly reduced (P less than 0.05) when compared to control calves.     

Effect of in ovo administered reovirus vaccines on immune responses of specific-pathogen-free chickens

We investigated the effect of in ovo administered reovirus vaccines on the immune responses of specific-pathogen-free chickens. T-cell mitogenic responses to concanavalin A were numerically lower at 9 and 12 days of age and significantly lower at 6 days of age in birds vaccinated with a commercial reovirus vaccine compared with unvaccinated birds or birds vaccinated with an experimental reovirus-antibody complex vaccine. There were no significant differences in proportions of subpopulations of helper (CD4+CD8-) or cytotoxic (CD4-CD8+) T cells except at 12 days of age, when the percentages of CD4-CD8+ cells in the two vaccinated groups were statistically higher than in the nonvaccinated group. B-cell populations were not different among vaccine groups except at 9 days of age, when the vaccinated groups had the highest level of B cells. This commercial reovirus vaccine should not be given in ovo to embryos having little or no maternal antibody, otherwise immunosuppression may occur in the chicks. The addition of the antibody complex to the vaccine prevented this T-cell immunosuppression.     

Immunogenicity of a temperature sensitive mutant Mycoplasma gaffisepticum vaccine

The immunogenicity of the ts-11 vaccine strain of Mycoplasma gallisepticum was assessed following eye drop or coarse aerosol administration in chickens of various ages. Protection was evalualted following intra-abdominal (IA) or fine droplet aerosol administration of virulent M. gallisepticum, usually the Ap3AS strain and was measured mainly by the scoring of gross air sac lesions or by egg production. Vaccination of chickens with ts-11 did not elicit a substantial serum antibody response as measured by rapid serum agglutination test, or ELISA. Protection was never demonstrated when no M. gallisepticum serum antibody response was detected in a vaccinated group of chickens. Failure to protect occurred usually, although not invariably, following aerosol administration of the vaccine. Vaccination by eye drop usually, although not invariably provided protection against challenge. In one experiment, chickens vaccinated by eye drop at 8-weeks were as susceptible as non vaccinated controls when challenged by IA inoculation at 13-weeks-of-age. Yet other birds from the same vaccinated group were resistant when challenged in an identical way at 23-weeks. No measurable increase in M. gallisepticum specific serum antibody concentrations occurred in the intervening period. Equally surprising was the response of another group of birds in the same experiment that had been vaccinated with a higher dose of ts-11. An antibody response was detected in this group, but they were susceptible to challenge at 23-weeks. Interestingly, a drop in egg production commenced 4 weeks after challenge, 2 weeks later than that observed in a non vaccinated group challenged at the same time.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cell-mediated and humoral immune response to Mycoplasma hyopneumoniae in pigs enhanced by dextran sulfate

The effect of dextran sulfate (DS), known to be cytotoxic to macrophages, on the cell-mediated and humoral immune response to nonviable Mycoplasma hyopneumoniae in pigs was investigated. The cell-mediated immune response was determined by means of lymphocyte transformation a test, using uptake of [3H]thymidine in a microculture system and the humoral immune response by means of a microplate complement-fixation test. Peripheral blood lymphocytes from pigs vaccinated with nonviable M hyopneumoniae and DS incorporated substantially more [3H]thymidine than did those from pigs given Mycoplasma or DS alone. The transformation of lymphocytes from M hyopneumoniae-DS vaccinated pigs was enhanced when M hyopneumoniae cells used in the assay system were heated at 60 C for 30 minutes. Similarly prepared M flocculare and M hyorhinis cells also stimulated lymphocytes from M hyopneumoniae-DS vaccinated pigs, but not nearly as great as when M hyopneumoniae cells were used. The humoral antibody response and the cell-mediated immune response to nonviable M hyopneumoniae was markedly enhanced by DS. Pigs were vaccinated with nonviable M hyopneumoniae and/or DS 4 times and challenge exposed intratracheally with viable M hyopneumoniae. Pigs vaccinated with M hyopneumoniae and DS had less severe pneumonia than did nonvaccinated pigs.     

Comparative evaluation of cell culture-adapted and chicken embryo-adapted fowl pox vaccine strains

Two types of vaccines, chicken embryo adapted (VacCE) and cell culture adapted (VacCC), were tested for their efficacy to elicite the immune response in birds vaccinated at 2 and 8 wk of age. The cell-mediated immune response studied by blastogenesis assay showed that birds vaccinated at the second week of age by both VacCE and VacCC vaccines had significant increase in T-lymphocyte count at 21 days postvaccination (PV) and 7 days postchallenge (PC), whereas in birds vaccinated at 8 wk of age, a significant increase was seen at 21 days PV and 7 days PC with the VacCC vaccine. The rise in passive hemagglutination titers was observed up to 21 days PV and 7 days PC in birds vaccinated at 2 wk of age. However, only the birds vaccinated with VacCC at 8 wk of age showed rise in titers at days 21 PV and 7 PC. Birds were challenged 90 days PV by scarification on the thigh region, and the birds vaccinated with VacCC showed 90% and 70% protection when vaccinated at 2 and 8 wk, respectively. The birds vaccinated with VacCE showed only 60% and 20% protection at the corresponding levels, respectively.     

Immunization against feline calicivirus infection.

Forty-three cats (experiments 1 and 2) were vaccinated (2 doses, 27 and 30 days between doses) with the F-9 strain of feline calicivirus by the intramuscular route. There was no untoward response in any of the cats to the administration of the vaccinal virus nor was there spread of the virus from 20 vaccinated cats to nonvaccinated cats held in contact during the next 6 months (experiment 2). The vaccinated cats developed serum-neutralizing antibodies that were increased further after the 2nd vaccination. The level of serum-neutralizing antibodies was related to the quantity of vaccinal virus administered. Twenty-three cats vaccinated with the F-9 strain were protected to a significant degree when challenge exposed to virulent calicivirus strain FPV-255 (experiment 1).     

Lesions of transmissible gastroenteritis virus infection in experimentally inoculated pigs suckling immunized sows

Intestinal lesions of transmissible gastroenteritis (TGE) virus infection in conventionally reared pigs suckling either nonvaccinated, vaccinated, or previously infected sows were studied by scanning electron microscopy, light microscopy, and immunofluorescent microscopy for TGE viral antigen. Pigs were inoculated with virulent TGE virus when they were 5 or 21 days old and were euthanatized shortly after the onset of diarrhea or 96 hours after inoculation if no diarrhea developed. Pigs inoculated when they were either 5 or 21 days old and suckling nonvaccinated sows developed severe lesions, including swelling and necrosis of enterocytes and severe villus atrophy. Pigs inoculated when they were 5 days old and suckling sows vaccinated with attenuated vaccines developed less-severe villus atrophy, and those suckling sows immunized by exposure to nonattenuated TGE virus developed moderate or no villus atrophy. Pigs inoculated when they were 21 days old and suckling sows vaccinated with attenuated vaccines had severe villus atrophy, whereas those suckling sows immunized by exposure to nonattenuated virus had more-moderate villus lesions. Villus atrophy was inhibited to various degrees in pigs suckling immunized sows, depending in part on the antibody titer in the colostrum and milk.     

Responses of horses vaccinated with avirulent modified-live equine arteritis virus propagated in the E. Derm (NBL-6) cell line to nasal inoculation with virulent virus

Nineteen horses with no prior experience with equine arteritis virus (EAV) were inoculated IM with an avirulent live-virus vaccine against equine viral arteritis; the vaccinal virus had been passaged serially 131 times in primary cell cultures of equine kidney, 111 times in primary cell cultures of rabbit kidney, and 16 times in an equine dermis cell line (EAV HK-131/RK-111/ED-16). Three or 4 of the vaccinated horses each, along with appropriate nonvaccinated controls, were inoculated nasally with virulent EAV at each of months 3, 6, 9, 12, 18, and 24 after they were vaccinated. The following was concluded: Vaccination did not induce clinical signs of disease in any horse and, thus, seemed safe for use in the field. All vaccinated horses (n = 19) developed serum-neutralizing antibodies to EAV. Fourteen of the vaccinated horses were completely protected from clinical arteritis when exposed to large doses of virulent EAV. Four were partially protected, and one had little or no protection. Six of 13 nonvaccinated horses died of acute arteritis, and the remaining 7 horses experienced severe signs of disease, but survived the infection. All horses (n = 32), whether vaccinated or not, became infected when inoculated nasally with virulent EAV. Virus was recovered from 17 of the 19 vaccinated horses, and all 19 had a secondary humoral immune response. The duration and severity of thermal reaction and persistence of virus were more transitory in vaccinated horses than in the nonvaccinated controls. Protection afforded by this vaccine can persist for at least 24 months, the maximal time after horses were vaccinated that immunity was challenged in the present study.(ABSTRACT TRUNCATED AT 250 WORDS)     

Mycoplasma gallisepticum vaccination: further studies on egg transmission and egg production

Leghorn hens vaccinated twice with an inactivated Mycoplasma gallisepticum (MG) bacterin before egg production and subsequently challenged with virulent MG were protected against transmission of MG through the egg. Unvaccinated control hens transmitted MG through the egg at a high rate. When unvaccinated hens were vaccinated with MG bacterin 2 weeks after challenge with MG, there was no significant decrease in egg transmission. Hens vaccinated twice before laying did not suffer as severe egg-production drops as unvaccinated hens did when challenged with virulent MG. In a natural MG outbreak in a leghorn breeder flock, 50 hens were separated from the remainder of the flock and vaccinated with MG bacterin approximately 3 weeks after initial exposure. The unvaccinated hens transmitted MG through the egg at a rate three times higher than the rate of transmission of the vaccinated hens.