Rabies Antibodies in Vaccinated Dogs

Forty-seven healthy, owned dogs were vaccinated with Madivak and 85 with Rabisin. Geometric mean titres of 17.40 and 1.03 IU/ml were measured by the rapid immunofluorescent focus inhibition test 30–40 and 350–370 days, respectively, after a single injection. Four out of 130 (3.1%) and 18 out of 106 (17% ) dogs had a titre of less than 0.5 IU/ml in serum 30–40 and 350–370 days after vaccination. Twenty-one dogs (19.8%) had a titre of 0.5 IU/ml 350–370 days after vaccinaton. There was no significant difference in antibody levels between animals vaccinated with Rabisin or Madivak. Our results indicate that a booster is always necessary after a single injection to ensure that all dogs have a lasting antibody titre.     

Estimation of post-vaccination antibody titre against goat pox and determination of protective antibody titre

Goats maintained in farm/under rural condition by individual owners with definite history of vaccination were vaccinated with Freeze Dried Tissue Culture Goat Pox Vaccine and antibody titre was determined up to 1 year post-vaccination period. A few experimental goats were vaccinated and subsequently challenged with isolated virulent field virus and antibody titre of vaccinated animals observed at different intervals was compared with the antibody titre observed in the experimental goats. Post-vaccination serum neutralizing antibody titre was 1:32 at 1 year post-vaccination. All the vaccinated experimental goats withstood virulent field virus challenge on 21st day with serum neutralizing antibody titre of 1:16.     

Immunogenicity and protective efficacy of solubilized merozoite-enriched Theileria sergenti immunogens. I: Protection against homologous stabilate challenge.

Theileria sergenti were isolated from infected erythrocytes by hypotonic lysis, and soluble merozoite antigens were purified by sonication and differential centrifugation. The preparation contained 29, 34, 35 and 105 kD immuno-dominant poly-peptides. The soluble antigens (0.5 mg/ml) were prepared and fortified with Freund's adjuvant. Five month old naive Korean calves were subcutaneously inoculated with the preparation and a booster dose was administered 4 weeks later. Nine weeks after the booster dose, vaccinates and controls were challenged with a homologous stabilate (5.6 x 10(6) RBC/dose, 40% Parasitemia). All animals were monitored for hematocrit, total erythrocyte count, parasitemia and for the specific antibody by Western immunoblot (WB) and indirect immuno-fluorescent antibody (IFA) test. By 18 weeks after vaccination (6 weeks after the challenge), vaccinated cattle had an average IFA titer of 1:10,240 compared with 1:1,280 of the controls. The vaccinates showed negligible change in hematocrit and total RBC count whereas control animals showed significant (p less than 0.05) hematological changes and associated anemia. After vaccination and challenge, the antibody responses demonstrated that vaccination had induced significant production of antibody to the 29 and 35 kD polypeptides. The latter polypeptide was much more strongly recognized by the vaccinated animals, and thus it may be a potential candidate for the vaccine.     

Rubella vaccination: persistence of antibodies for up to 16 years.

Sera from 123 volunteers vaccinated six to 16 years previously with one of four rubella vaccines (Cendehill, RA27/3, HPV77-DE5, and To-336) were tested for rubella antibodies by single radial haemolysis and radioimmunoassay. By radioimmunoassay 110 (89.4%) of the vaccinees had antibody concentrations greater than the minimum immune titre (that is, greater than 15,000 IU/1), 11 (8.9%) were seropositive but had concentrations less than or equal to 15,000 IU/1, and two (1.6%) were seronegative. Eight (6.5%) were seronegative by single radial haemolysis, of whom five had received Cendehill vaccine. Six to eight years after vaccination subjects who had received Cendehill vaccine had the lowest geometric mean titre of antibody by radioimmunoassay while the subjects who had received HPV77-DE5 vaccine had the highest. Although antibody concentrations less than or equal to 15,000 IU/1 were not detected among subjects given RA27/3 vaccine six to eight years previously, such low levels were detected in two (15.4%) vaccinated 11-16 years previously. These results emphasise the importance of long-term surveillance programmes so that vaccination policies may be reviewed.     

Immunogenicity and Safety in Adults of a New Chromatographically Purified Vero-cell Rabies Vaccine (CPRV): a Randomized, Double-blind Trial with Purified Vero-cell Rabies Vaccine (PVRV)

Recent improvements in chromatographic purification procedures have made it possible to develop a new chromatographically purified rabies vaccine (CPRV) by further purifying the current rabies vaccine prepared from Vero-cell culture (Verorab; Pasteur Mérieux Connaught). The immunogenicity and safety of primary immunization, followed by a booster at one year, with CPRV was compared to that of the purified Vero cell vaccine (PVRV) in a randomized, double-blind study carried out at four veterinary schools in France. A total of 330 healthy, male and female, first-year veterinary students, aged at least 18 years and who required pre-exposure rabies prophylaxis, were enrolled in this study. Included subjects were randomly assigned either CPRV (n = 163) or PVRV (n = 167) to be given as a primary immunization series of three intramuscular injections (D0, D7, D28), followed by a booster after 1 year (D365). Blood samples for serological analysis were taken at D0 (before first injection), D28, D42, D180, D365 (before booster) and D379. All subjects developed a strong immune response to the primary series, and at D42, all subjects had seroconverted for rabies neutralizing antibody (serum titre > or = 0.5 IU/ml). The rabies virus-neutralizing antibody GMT value at D42 in the CPRV group (23.0 IU/ml) was non-inferior to that in the PVRV group (29.6 IU/ml), according to a one-sided non-inferiority test. While antibody titres tended to decrease over the period of follow-up, at D365 (before booster), 97.5% subjects in the CPRV group and 98.8% of subjects in the PVRV group remained seroconverted. After booster, although the rabies antibody GMT value in the CPRV group was lower than that in the PVRV group, all subjects in both groups were seroconverted, and the difference is probably not clinically important. The incidence of local and systemic reactions tended to decrease with each dose during the primary immunization series, followed by a slight increase after booster (significant time-effect in an exploratory logistic regression analysis). Although mild or moderate local reactions tended to be more frequent after injection with CPRV compared to PVRV, systemic reactions were reported less often (significant group-effects in exploratory logistic regression analyses). One serious adverse event possibly related to vaccine occurred during this study (severe asthenia after the third dose of PVRV). This comparative study in healthy young adults demonstrates that the new chromatographically purified rabies vaccine is as immunogenic as PVRV, and seems to be associated with fewer systemic reactions.     

Seroresponse (IgG) after Vaccination and Natural Infection of Cattle with Babesia Divergens

The antibody response against Babesia divergens in vaccinated calves and in unvaccinated sentinels on farms where vaccination had been practiced routinely, was investigated using a live vaccine. Sera were obtained before and 3 weeks after vaccination in March and April, approximately 1 month before the animals were put out on pasture. Additional blood samples were collected at the end of the grazing season and again the next spring. At that time previously unvaccinated sentinel calves were vaccinated and their antibody response was tested 3 weeks later. All sera were analysed by an IF-technique. All of the vaccinated calves (100%) were seropositive 3 weeks after vaccination. The seroresponse did not differ signifacantly between animals vaccinated before their first or second grazing season although the age difference was about 12 months. No clinical symptoms of babesiosis were seen in vaccinated animals. The titres were, however, significantly higher 3 weeks after vaccination than 6 months later. After the grazing season about 42% of the unvaccinated sentinel calves were sero–positve. Two of these calves had clinical babesiosis on pasture in July and September respectively. The number of sentinel calves which became infected on pasture showed a large farm-to-farm variation although all cattle on the farms once had been infected-/vaccinated with B. divergens. Probably the different number of calves infected was a reflection of a variation in tick density on the different pastures. All calves, which were seropositive after the grazing season, were also seropositive after 6 months indoors. The titres declined during the winter period, but they were still within the range of 2 doubling dilution steps.     

麻疹减毒活疫苗不同剂量初免及复种后的免疫效果研究

目的评价麻疹减毒活疫苗（Measles Attenuated Live Vaccine,MV）不同接种剂量在初免及复种后的免疫效果及差异性。方法在同一观察区域、不同时段对适龄儿童分成两组采用MV0.2 ml与0.5 ml接种剂量分别在初免和复种后进行麻疹IgG抗体滴度测定。结果初免后,0.5 ml组较0.2 ml组IgG抗体阳性率、保护率分别提高5.28%与9.79%,抗体几何平均滴度（GMT）由1：543.03提高至1：813.51;初免加复种后,0.5 ml组较0.2 ml组阳性率、保护率分别提高5.32%与3.98%,GMT由1：740.49提高至1：1098.30;初免加复种较单一初免的阳性率、GMT差异有统计学意义。结论初免接种剂量0.5 ml可提高IgG抗体阳转率;复种0.5 ml与0.2 ml组的保护率差异无统计学意义,但0.5 ml组抗体阳性率、GMT较高。     

Immunity to diphtheria, six to 15 years after a basic three-dose immunization schedule

The results of a study of the immunity to diphtheria of 283 girls (9-18 years of age) vaccinated at the age of two years with three doses of vaccine, are reported. The rabbit skin test was used to determine the titre of serum diphtheria antitoxin. 55.8% of the subjects were found to be protected (titre greater than or equal to 0.1 IU/ml), 38.9% were only relatively immune (titre greater than or equal to 0.01- less than 0.01 IU/ml), and 5.3% were unprotected (titre less than 0.01 IU/ml). The antitoxin titres showed a tendency to decrease with time. Even so, 6-15 years after vaccination, the percentages of protected and partially protected subjects were still high (95%).     

Detection of rabies virus antibodies in Brazilian free-ranging wild carnivores

Rabies virus is a pathogen of major concern in free-ranging wild carnivores in several regions of the world, but little is known about its circulation in Brazilian wild carnivores. Sera from 211 free-ranging wild carnivores, captured from 2000 to 2006 in four locations of two Brazilian biomes (Pantanal and Cerrado), were tested for rabies antibodies. Twenty-six individuals (12.3%) had neutralizing antibody titers ≥0.10 IU/ml. The four sampled locations had antibody-positive animals, suggesting that Rabies virus circulates in all of these regions. Results underscore the risk posed by rabies for conservation of Brazilian carnivores and the possibility of the animals acting as reservoirs for the Rabies virus.     

Antibody Response to a Human Diploid Cell Rabies Vaccine

An experimentally killed rabies virus vaccine prepared in a human diploid cell strain (WI-38)—Wyeth rabies vaccine (WRV)—was used by various injection schedules in two separate studies to define more closely in human volunteer subjects an effective vaccination schedule for pre- or postexposure immunization, particularly for donors of rabies-hyperimmune plasma. To permit valid comparisons between our results and those of other workers, antibody levels achieved were expressed in terms of international units (IU) per milliliter of serum. Antibody response of previously nonvaccinated persons were only modest after a single dose of WRV, never reaching a level higher than 0.80 IU/ml over a 56-day testing period. Moreover, antibody was not detected at 0.16 IU/ml before the 14th day, either after a single dose or after two doses given 3 days apart. The best response followed four doses of WRV given within 4 weeks. This schedule resulted in the highest rate of seroconversion to the ≥6 IU/ml antibody level required of potential rabies-immune plasma donors. Giving the first vaccine dose in aluminum hydroxide diluent did not enhance the antibody response. There was a definite suggestion in the various injection schedules that higher and more sustained antibody levels were reached when the interval between the first and second vaccine doses was longest. The greater immunogenicity of WRV as compared with duck embryo vaccine was best demonstrated by the fact that a single booster dose of duck embryo vaccine to previously vaccinated individuals resulted in only a sevenfold antibody rise during the following 56 days, whereas a booster dose of WRV elicited a 69-fold rise. Al(OH)₃ in the first dose of WRV had no effect, but the enhancing effect of a longer interval between vaccine doses was noted once again; 20 of 20 subjects who received three doses of WRV with 4 weeks between doses developed good levels of rabies antibody, and 19 exceeded 6 IU/ml.     

ELISA for the routine determination of antitoxic immunity to tetanus

Serum samples from 727 persons with different vaccination histories were assessed for tetanus antitoxin content in an enzyme linked immunosorbent assay (ELISA) and tested for tetanus toxin neutralization activity in mice in order to compare the results obtained by the two methods. Neutralizing antibody activities in sera from individuals previously completely vaccinated correlated well with results obtained by ELISA and the accuracy increased with increasing antitoxin concentration in serum. This correlation was observed in sera from persons vaccinated recently as well as in sera from persons vaccinated many years ago. In sera from persons with an incomplete vaccination history ELISA was found to be an unreliable tool for the prediction of in vivo results. Many of these sera had antitoxin levels by ELISA far above the in vivo values, probably due to the presence of non specific or low avidity antitoxin which is detected in ELISA. The lowest ELISA value reliably predictive of protective antibody activity in serum irrespective of vaccination history was found to be 0.16 IU/ml. It was concluded that ELISA is useful for larger population studies as an initial test, but sera with an antitoxin content below 0.16 IU/ml should also be assessed in a neutralization system.     

Effect of vaccination against gonadotropin-releasing factor (GnRF) with Bopriva® in the prepubertal bull calf

The aim of this study was to evaluate the effect of immunization against gonadotropin-releasing factor (GnRF) with Bopriva(?) (Pfizer Animal Health, Parkville, Australia) in prepubertal bull calves. For the study, 6 calves were vaccinated at the age of 3 and 6 weeks with 1 mL Bopriva(?), and 6 animals served as matched controls. Concentrations of GnRF antibodies, testosterone and LH were determined in serum samples out to 30 weeks after the first immunization. Body weight and scrotal circumference were measured for 59 weeks. At slaughter, 65 weeks after the first immunization, the quality of epididymal sperm was evaluated. The results showed that vaccination against GnRF influenced (P<0.05) anti-GnRF titer, LH and testosterone concentrations as well as scrotal circumference. Antibody titers significantly (P<0.05) increased after the booster vaccination and reached peak values 2 weeks later. Compared to control animals, inhibition (P<0.05) of the prepubertal LH secretion was observed in vaccinated calves at weeks 10 and 12-14 after the first vaccination. In vaccinated calves testosterone concentrations decreased after the booster injection to values below 0.5 ng/mL serum and remained for at least 22 weeks at this low level. Animals vaccinated with Bopriva(?) showed a delay in testes growth and smaller scrotal circumference. Puberty occurred at the age between 46 and 55 weeks in vaccinated and between 38 and 52 weeks in control animals and body weight gain was similar in both groups. All vaccinated bulls attained spermatogenic capacity at slaughter when they were 68 weeks old.     

Booster vaccination with live attenuated Vibrio anguillarum elicits strong protection despite weak specific antibody response in zebrafish

A live attenuated Vibrio anguillarum vaccine was recently established in the laboratory that induced immunoprotection against vibriosis in zebrafish, Danio rerio. To improve immunogenicity, the effects of different booster vaccination regimens were investigated using bath‐vaccination in a zebrafish model. Zebrafish receiving booster doses at 2 weeks or at both 2 and 4 weeks after primary vaccination were better protected in comparison to fish that received a single vaccination. In addition, the booster vaccination induced a prolonged specific antibody response. No correlation between a weak specific antibody response and a strong protection was observed, indicating that the booster vaccination could enhance the affinity of Immunoglobulin M (IgM) rather than the amount. Moreover, changes in the immune‐related gene expression of the booster‐vaccinated group suggested that the booster enhanced the adaptive immune responses.     

Use of the toxin-binding inhibition test for estimation of tetanus antitoxin in serum

The usefulness of the toxin binding inhibition test (ToBI) for the titration of tetanus antibody in human sera was assessed. Sera from 80 healthy people with different vaccination histories that had been previously tested by the in vivo toxin neutralization (TN) test were retested by the ToBI test. The lowest tetanus antibody titre which could be detected by using 0.1 Lf/ml tetanus toxin was 0.01 IU/ml. Comparison between the estimates obtained by the ToBI test and those obtained by the TN test (r = 0.93 and r = 0.7 for titration low titre sera) showed good correlation. No overestimation of antibody content was seen in titrating low titre sera by the ToBI test. It is concluded that the ToBI-test is a reliable alternative to toxin neutralization test in mice.     

Assessing immune competence in pigs by immunization with tetanus toxoid

Immune competence can be tested by challenging organisms with a set of infectious agents. However, disease control requirements impose restrictions on the infliction of infections upon domestic pigs. Alternatively, vaccinations induce detectable immune responses that reflect immune competence. Here, we tested this approach with tetanus toxoid (TT) in young domestic pigs. To optimize the vaccination protocol, we immunized the pigs with a commercial TT vaccine at the age of 21 or 35 days. Booster immunizations were performed either 14 or 21 days later. TT-specific antibodies in plasma as well as lymphoproliferative responses were determined both 7 and 14 days after booster immunization using ELISA and lymphocyte transformation tests, respectively. In addition, general IgG and IgM plasma concentrations and mitogen-induced proliferation were measured. The highest TT-specific antibody responses were detected when blood samples were collected 1 week after a booster immunization conducted 21 days after primary immunization. The pigs’ age at primary immunization did not have a significant influence on TT-specific antibody responses. Similarly, the TT-specific proliferative responses were highest when blood samples were collected 1 week after booster immunization, while age and time of primary and booster immunization were irrelevant in our setup. While general IgG and IgM plasma levels were highly age dependent, there were no significant age effects for TT-specific immune responses. In addition, mitogen-induced proliferation was independent of immunization as well as blood sampling protocols. In summary, our model of TT vaccination provides an interesting approach for the assessment of immune competence in young pigs. The detected vaccination effects were not biased by age, even though our data were acquired from immune systems that were under development during our tests.     

Evaluation of rabies virus neutralizing antibody titres induced by intramuscular inoculation of rabies DNA vaccine in mice and Bonnet monkeys (Macaca radiata)

A rabies DNA vaccine consisting of plasmid DNA expressing the rabies virus surface glycoprotein was injected (im) twice at two week interval to outbred swiss mice or Bonnet monkeys (Macaca radiata) and the levels of rabies virus neutralizing antibody (VNA) titres were examined over a one year period. In mice, the VNA titre was maintained above the minimum protective level (0.5 I.U./ml) up to 10 months after primary immunization, while in monkeys, the titre dropped below the protective level by 6 months. An anamnestic B cell response was seen in both mice and monkeys following the administration of a booster dose, 10 and 6 months after the primary immunization, respectively. These results indicate that im injection of rabies DNA vaccine induces VNA in nonhuman primates and mice unlike intradermal (id) immunization, which was shown to induce VNA only in mice but not in monkeys. This is the first report on the induction of VNA in nonhuman primates by im inoculation of rabies DNA vaccine.     

Vaccination against gonadotropin-releasing factor (GnRF) with Bopriva significantly decreases testicular development, serum testosterone levels and physical activity in pubertal bulls

The aim of this study was to evaluate the effects of vaccination against gonadotropin-releasing factor (GnRF) on testicular development, testosterone secretion, and physical activity in pubertal bulls. The experiment was performed using 44 bulls aged between 6 and 7 mo. Twenty-three animals were vaccinated twice 4 wk apart with 1 mL of Bopriva (Pfizer, Animal Health, Parkville, Australia) and 21 bulls served as matched controls. Serum GnRF antibody titer and testosterone concentration as well as body weight and scrotal circumference were determined in all bulls for 24 wk from the first vaccination. In addition, physical activity was analyzed in 11 vaccinated and in 10 control animals using the ALPRO DeLaval activity meter system (DeLaval AG, Sursee, Switzerland). The results show that vaccination significantly (P < 0.05) influenced all parameters evaluated except body weight. Antibody titers to GnRF began to rise 2 wk after the first vaccination and reached peak values 2 wk after the second injection. Significant group differences in anti-GnRF titer were present for 22 wk following the first vaccination. Testosterone concentrations were significantly lower between weeks 6 to 24 after first vaccination in bulls with Bopriva compared with control animals. In vaccinated bulls testicular development was impaired after the second injection and scrotal circumference was significantly smaller between weeks 8 to 24 after first vaccination. Physical activity of vaccinated bulls was reduced after the booster injection with significant group differences for a continuous period of 106 days. In conclusion, vaccination against GnRF with Bopriva in pubertal bulls decreased testosterone levels in peripheral blood, testicular development, and physical activity but did not affect weight gain.     

Reproductive and safety assessment of vaccination with Gavac against the cattle tick (Boophilus microplus)

Recent developments in cattle tick control have incorporated the use of recombinant Bm86 vaccines against this ectoparasite. The vaccine developed by our group (Gavac) contains an antigen expressed in Pichia pastoris, and has been successfully employed for the control of tick infestations and transmission of tick-borne diseases. Here, we examined the safety and effect of the Gavac vaccine on reproductive parameters in cattle. Toxicity tests in mice and guinea pigs demonstrated the safety of Gavac. To study the adverse effects of vaccination on reproduction, a field trial involving 9,500 animals in Cuba was conducted. The cattle at 3 farms were vaccinated while those on a fourth farm were left unvaccinated and served as the control. Following vaccination, the control of tick infestation and the transmission of babesiosis were used to demonstrate the efficacy of the vaccine. No adverse effects were observed in any of the reproductive parameters studied when comparing the data before and after vaccination with Gavac and between the vaccinated farms and the control farm. These results demonstrate that under the conditions of our study vaccination with Gavac is safe for use on cattle.     

Efficacy of an Inactivated Porcine Parvovirus (PPV) Vaccine under Field Conditions

Dose response experiments were carried out by vaccinating groups of seronegative gilts (7 months of age) and groups of gilts with residual maternal serum antibodies to PPV (5 months of age). PPV vaccines containing different amounts of inactivated virions were used. Vaccinations were carried out twice with 3 weeks intervals. It was demonstrated, that a single vaccination even with a vaccine with low antigen content elicited an antibody response to PPV in seronegative gilts. The titer values increased after the 2nd vaccination. When the gilts had residual maternal serum antibodies at the time of vaccination the antibody response was generally lower. In some animals the titer values decreased after the 1st vaccination, but except for 2 gilts vaccinated with vaccines with a low antigen content an increase of titer values followed after the 2nd vaccination. During a field trial performed in a herd with enzootic PPV infection all the gilts were vaccinated with PPV vaccine before mating. Blood samples were examined for HI antibodies before and after vaccination and at weaning time of each of the resulting 5 litters. In total 24 batches of gilts comprising 326 animals mated during a 2 year period were examined. It was demonstrated, that the applied vaccine preparations used under field conditions gave a relatively high and long lasting antibody response, even when the gilts were vaccinated as early as at about 5 months of age.     

Vaccination with F1-V fusion protein protects black-footed ferrets (Mustela nigripes) against plague upon oral challenge with Yersinia pestis

Previous studies have established that vaccination of black-footed ferrets (Mustela nigripes) with F1-V fusion protein by subcutaneous (SC) injection protects the animals against plague upon injection of the bacterium Yersinia pestis. This study demonstrates that the F1-V antigen can also protect ferrets against plague contracted via ingestion of a Y. pestis-infected mouse, a probable route for natural infection. Eight black-footed ferret kits were vaccinated with F1-V protein by SC injection at approximately 60 days-of-age. A booster vaccination was administered 3 mo later via SC injection. Four additional ferret kits received placebos. The animals were challenged 6 wk after the boost by feeding each one a Y. pestis-infected mouse. All eight vaccinates survived challenge, while the four controls succumbed to plague within 3 days after exposure. To determine the duration of antibody postvaccination, 18 additional black-footed ferret kits were vaccinated and boosted with F1-V by SC injection at 60 and 120 days-of-age. High titers to both F1 and V (mean reciprocal titers of 18,552 and 99,862, respectively) were found in all vaccinates up to 2 yr postvaccination, whereas seven control animals remained antibody negative throughout the same time period.