VACCINATION OF PREGNANT COWS WITH LOW DOSES OF BRUCELLA ABORTUS STRAIN 19 VACCINE

Two groups, each of 9 Jersey cows, were vaccinated subcutaneously with reduced doses of Brucella abortus strain 19 vaccine (measured by the number of bacteria in the vaccine dose) early in their second pregnancy. Ten weeks later they were challenged, along with a similar group of non-vaccinated cows, by conjunctival instillation of a virulent strain of B. abortus biotype 1. Cows in Group 1 received 1/20th and those in Group 2 received 1/400th the recommended dose of strain 19. Marked reduction in the serological response to vaccination was seen only in Group 2. Four cows in Group 1 excreted strain 19 after parturition, one of them aborted and another calved prematurely with heavy infection of the placenta and foetus with strain 19 in both cases. Resistance to challenge was similar in both vaccinated groups, and higher than previously demonstrated after conventional calfhood vaccination with strain 19. It is concluded that pregnant cows can be effectively vaccinated by the subcutaneous administration of a dose of strain 19 vaccine containing approximately 3 x 10(8) organisms without undue interference with subsequent serological tests or inconvenience resulting from persistence of strain 19 infection.     

Clinical and immunological responses of ewes following vaccination with an experimental formalin-inactivated Chlamydia psittaci (ovis) vaccine and subsequent challenge with the live organism during pregnancy

The protection afforded by an experimental, killed, adjuvanted vaccine derived from the A22 strain of Chlamydia psittaci (ovis) against ovine enzootic abortion was studied. The vaccine was used undiluted (group A), at a dilution of 10(-3) (group B) and at a dilution of 10(-6) (group C). A fourth control group (group D) was inoculated with all components of the vaccine except the chlamydial antigen. A group of rams (group R) was also vaccinated with the chlamydial antigen diluted to 10(-3). Animals were challenged 70 days after mating with the A22 strain of C. psittaci (ovis) and were studied throughout pregnancy and the subsequent lambing period. Their cell-mediated immune responses were examined using a skin test and their humoral immune responses were studied using an ELISA. Tests for excretion of chlamydiae in their faeces and genital tract during pregnancy and after parturition and in the faeces of their lambs were made. The reproductive performance of the ewes was assessed by calculating the average weight of lambs produced per ewe in each group. The experimental vaccine protected the ewes in groups A and B against challenge with C. psittaci (ovis) as none showed clinical signs of OEA or excreted chlamydiae. The average weight of lambs produced per ewe in both groups was greater than 4 kg. Both groups seroconverted after vaccination but not all of them were positive to the skin test. The experimental vaccine at 10(-6) dilution of antigen did not protect the ewes as three of 10 ewes displayed clinical OEA and excreted chlamydiae in the products of parturition.(ABSTRACT TRUNCATED AT 250 WORDS)     

Parenteral vaccination of domestic pigs with Brucella abortus strain RB51

OBJECTIVE: To determine the immunogenicity and efficacy of Brucella abortus strain RB51 (SRB51) as a vaccine in domestic pigs. ANIMALS: Sixty-eight 6-week-old crossbred domestic pigs and twenty-four 4-month-old gilts. PROCEDURES: In experiment 1, pigs were vaccinated IM (n = 51) with 2 x 10(10) CFUs of SRB51 or sham inoculated (17). Periodic blood samples were obtained to perform blood cultures, serologic evaluations, and cell-mediated immunity assays. Necropsies were performed at selected times between weeks 1 and 23 after vaccination to determine vaccine clearance. In experiment 2, gilts were similarly vaccinated (n = 18) or sham inoculated (8) and similar samples were obtained after vaccination. Gilts were bred and challenged conjunctivally with 5.0 x 10(7) CFUs of virulent Brucella suis strain 3B. Necropsies were performed on gilts and on fetuses or neonates after abortion or parturition, respectively. Bacterial cultures and serologic evaluations were performed on samples obtained at necropsy to determine vaccine efficacy. RESULTS: Humoral and cell-mediated immune responses did not differ between vaccinates and controls. After vaccination, SRB51 was not isolated from blood cultures of either group and was isolated from lymphoid tissues of 3 pigs at 2 weeks (n = 2) and 4 weeks (1) after vaccination. No differences were found in isolation of B suis or in seroconversion between vaccinated and control gilts and between their neonates or aborted fetuses. CONCLUSIONS AND CLINICAL RElEVANCE: Parenteral vaccination with SRB51 does not induce humoral or cell-mediated immune responses. Vaccination with SRB51 did not protect gilts or their neonates and fetuses from virulent challenge with B suis.     

Pathogenicity and protective activity in pregnant goats of a Brucella melitensis Deltaomp25 deletion mutant

The Brucella melitensis mutant BM 25, which lacks the major 25 kDa outer membrane protein Omp25, has previously been found to be attenuated in the murine brucellosis model. In the present study, the capacity of the Deltaomp25 mutant to colonise and cause abortions in the caprine host was evaluated. The vaccine potential of BM 25 was also investigated in goats. Inoculation of nine pregnant goats in late gestation with the B. melitensis mutant resulted in 0/9 abortions, while the virulent parental strain, B. melitensis 16M, induced 6/6 dams to abort (P<0.001, n=6). BM 25 also colonised fewer adults (P<0.05, n=6) and kids (P<0.01, n=6) than strain 16M. The Deltaomp25 mutant was found capable of transient in vivo colonisation of non-pregnant goats for two weeks post-infection. Owing to the ability of BM 25 to colonise both non-pregnant and pregnant adults without inducing abortions, a vaccine efficacy study was performed. Vaccination of goats prior to breeding with either BM 25 or the current caprine vaccine B. melitensis strain Rev. 1 resulted in 100 per cent protection against abortion following challenge in late gestation with virulent strain 16M (P<0.05, n=7). However, unlike strain Rev. 1, BM 25 does not appear to cause abortions in late gestation based on this study with a small number of animals. The B. melitensis Deltaomp25 mutant, BM 25, may be a safe and efficacious alternative to strain Rev. 1 when dealing with goat herds of mixed age and pregnancy status.     

Experimental infection of goats at different stages of pregnancy with caprine herpesvirus 1

Three goats from a group of five caprine herpesvirus 1 (CpHV.1) seronegative pregnant goats were inoculated intranasally with a virulent BA.1 strain of CpHV.1. Goat n.1 was infected on day 45 of pregnancy, goat n.2 on day 92 and goat n.3 on day 127. Each of the three goats produced a single foetus 10-60 days after infection. Foetus n.1 was never found and so it could not be examined for virological findings. Goat n.2 delivered at term of gestation and CpHV.1 was detected by PCR and isolated from most of the foetal organs. Foetus n.3 was partially autolysed and the virus was only detected by PCR but not isolated from foetal organs. The results confirm the damaging effect of CpHV.1 infection on pregnancy, the difficulty in diagnosing the CpHV.1 induced abortion, and the importance developing appropriate prophylactic programmes.     

Abortion in humans caused by Chlamydophila abortus (Chlamydia psittaci serovar 1)

On a farm housing cattle and goats an abortion storm occurred affecting 50% of the goats during the lambing season 2000/2001. In one of three investigated caprine abortions Chlamydophila abortus could be identified as etiology. During this time a pregnant woman (pregnancy week 19/20) had contact with aborting goats. She developed a severe generalized infection and aborted. The placenta contained Chlamydophila abortus shown by immunohistochemistry and PCR. Aim of the present case report is to alert veterinarians about the potential zoonotic risk of ovine/caprine abortions.     

Experimental Coxiella burnetii infection in pregnant goats: excretion routes

Q fever is a widespread zoonosis caused by Coxiella burnetii. Infected animals, shedding bacteria by different routes, constitute contamination sources for humans and the environment. To study Coxiella excretion, pregnant goats were inoculated by the subcutaneous route in a site localized just in front of the shoulder at 90 days of gestation with 3 doses of bacteria (10(8), 10(6) or 10(4) i.d.). All the goats aborted whatever the dose used. Coxiella were found by PCR and immunofluorescence tests in all placentas and in several organs of at least one fetus per goat. At abortion, all the goats excreted bacteria in vaginal discharges up to 14 days and in milk samples up to 52 days. A few goats excreted Coxiella in their feces before abortion, and all goats, excreted bacteria in their feces after abortion. Antibody titers against Coxiella increased from 21 days post inoculation to the end of the experiment. For a Q fever diagnostic, detection by PCR and immunofluorescence tests of Coxiella in parturition products and vaginal secretions at abortion should be preferred to serological tests.     

Immune potency of lyophilized, killed vaccine for equine viral arteritis and its protection against abortion in pregnant mares

Immune potency test was conducted in horses by inoculating a killed vaccine for equine viral arteritis (EVA) which had been freeze-dried and contained aluminum hydroxide adjuvant. Serum neutralizing (SN) antibody to equine arteritis virus (EAV) was detected at maximal titers of 1:80 to 1:640, 1 to 2 weeks after 2-dose vaccination of 6 female horses. However, 6 pregnant mares inoculated with the vaccine which had been kept in storage for 1 year at 4°C produced much higher titers ranging from 1:320 to 1:1280. A maximal mean titer of 1:199.5 occurred in the 1st and 2nd week after 2-dose inoculation with the nonpreserved vaccine, whereas a maximal mean titer of 1:794.3 occurred in the 2nd week using the preserved vaccine. The horses showed no systemic or local adverse reactions clinically or hematologically after vaccination. Four of the 6 vaccinated pregnant mares were exposed to the Bucyrus strain of EAV but resisted challenge exposure, while 3 nonvaccinated control pregnant mares revealed acute EVA causing abortion and death. Isolation of EAV was positive from the body tissues of the aborted and dead fetuses and their dams, but was negative from the vaccinated mares. No significant rise of SN antibody titers was detected in the vaccinated mares following challenge exposure, suggesting that the vaccine can protect against EAV infection in pregnant mares and prevent abortion or death.     

Abortion induced by cell-associated pseudorabies virus in vaccinated sows.

Pregnant sows, immune against pseudorabies after vaccination, were inoculated at 70 days of gestation either with autologous blood mononuclear cells that had been infected in vitro with pseudorabies virus (PRV) or with cell-free PRV. The infected cells or cell-free PRV were inoculated surgically into the arteria uterina. Eight sows (A to H) had been vaccinated with an inactivated vaccine. The titer of seroneutralizing antibodies in their serum varied between 12 and 48. Five sows (A to E) were inoculated with autologous mononuclear cells, infected either with a Belgian PRV field strain or with the Northern Ireland PRV strain NIA3. These 5 sows aborted their fetuses: 2 of them (B and C) 3 days after inoculation, and the other 3 (A, D, and E) 10, 11, and 12 days after inoculation, respectively. Sows F, G, and H were inoculated with a cell-free PRV field strain. They farrowed healthy litters after normal gestation. Neutralizing antibodies were absent against PRV in the sera of the newborn pigs, which were obtained prior to the uptake of colostrum. The 23 fetuses that were aborted in sows B and C 3 days after the inoculation were homogeneous in appearance and size. Foci of necrosis were not detected in the liver. Viral antigens were located by immunofluorescence in individual cells in lungs, liver, and spleen of 15 fetuses. Virus was isolated from the liver, lungs, or body fluids of 12 fetuses. The 39 fetuses that were aborted in sows A, D, and E between 10 and 12 days after inoculation were of 2 types: 17 were mummified and 22 were normal-appearing.(ABSTRACT TRUNCATED AT 250 WORDS)     

Induction of antibodies to glycoprotein I in pigs exposed to different doses of a mildly virulent strain of Aujeszky's disease virus

It has recently been shown that the antibody response to glycoprotein I (gI) of Aujeszky's disease virus can be used to distinguish infected from vaccinated pigs. To examine whether pigs exposed to low doses of a mildly virulent strain of Aujeszky's disease virus produce antibody to gI four groups of four pigs were inoculated intranasally with 10, 10(2), 10(3) or 10(4) plaque forming units (PFU) of the Sterksel strain. Two unvaccinated pigs and two pigs vaccinated intranasally with Bartha's K strain, a gI-negative vaccine, were placed in contact with each group. The pigs given 10 PFU and the in-contact pigs in this group did not become infected. The inoculated and the unvaccinated in-contact pigs in the other groups developed mild signs of illness and produced antibody to gI. Four of six vaccinated in-contact pigs that became infected showed neither clinical signs nor virus shedding and still produced antibody to gI. The other two vaccinated pigs appeared to be resistant to contact-challenge. The antibody response to gI persisted for at least seven months. These results support the idea that Aujeszky's disease virus may be eradicated by a programme based on vaccination with gI-negative vaccines, in conjunction with the detection and subsequent removal of gI-antibody positive, infected, pigs.     

Caprine enzootic arthritis-encephalitis in France: epidemiological and experimental studies

In an epidemiological study on CAEV-induced caprine arthritis, the ELISA carried out on mixed sera appeared to be an efficient pointer to viral articular pathology in flocks; the breed and origin of goats, the selection of flocks with high milk production proved to be factors which favour viral arthritis, the serological diagnosis of which remains a flock diagnosis. In addition, in an experimental infection, only one type II caprine strain induced significant cases of arthritis; the disease could be reproduced more effectively by the intra-articular route than intravenously. Lastly, in a vaccination test followed by infectious CAEV challenge, two vaccinated goats showed more severe arthritis than did non vaccinated control goats. These observations emphasise the importance of the different viral strains, of the penetration route of the virus, of the repetition of infections and of the immune response in the induction of CAEV arthritis.     

Protection by oral administration of brucella abortus strain 19 against an oral challenge exposure with a pathogenic strain of Brucella

Twenty heifers were vaccinated orally with Brucella abortus strain 19. These heifers and 21 control heifers were challenge exposed in midgestation with strain 2308 by the oral route. Ten of 19 pregnant control heifers aborted and 14 were culture positive. Two additional heifers were seropositive at slaughter. Strain 2308 was recovered from 4 vaccinates at slaughter; none of the vaccinates aborted. Titers after oral vaccination persisted for less than 82 days.     

Effect of Vaccination with Brucella abortus Strain RB51 on Heifers and Pregnant Cattle

Thirteen cows, which had been vaccinated as calves with strain 19, were revaccinated twice or three times as adults with 1×10⁹ cfu of B. abortus strain RB51. Their serological responses following adult vaccination remained negative to conventional brucellosis surveillance tests. Vaccination with strain RB51 during the eighth month of pregnancy did not induce abortion, although strain RB51 was recovered from milk for up to 69 days after vaccination. In a parallel study, thirteen 8- to 10-month-old heifers were vaccinated as calves with 10⁹ cfu of strain RB51. The heifers remained seronegative to conventional brucellosis surveillance tests but antibody responses to RB51 could be demonstrated using an indirect ELISA. This study showed that multiple vaccination with strain RB51 did not induce seroconversion to brucellosis surveillance tests. In addition, this study suggests that 10⁹ cfu of strain RB51 is safe for use in pregnant cattle.     

Infectivity virulence and immunogenicity of Anaplasma centrale live blood vaccine

Cross-bred Bos taurus calves, aged between 6 and 8 months, were inoculated with the Onderstepoort Anaplasma centrale live blood vaccine. One group of 15 calves were inoculated once only, while a 2nd group of 15 were revaccinated 6 months later. All the animals were challenged with approximately 1 X 10(10) Anaplasma marginale parasites of a known virulent strain 8 months after the first vaccination. The results of blood smear examination and the card agglutination test indicated that only 20 out of 30 animals vaccinated contracted A. centrale infections after the first attempt, and 3 out of 5 after the second. The vaccine conferred only partial immunity to challenge with a virulent A. marginale strain.     

Experimental respiratory infection of goats with caprine herpesvirus and Pasteurella haemolytica

Groups of six male goats were inoculated intratracheally and intranasally with either caprine herpesvirus followed 6 days later by Pasteurella haemolytica, canine herpesvirus alone or P. haemolytica alone. Pneumonic lesions were observed in five of the six goats inoculated with caprine herpesvirus followed by P. haemolytica and in three of the six goats inoculated with P. haemolytica alone, but were not observed in goats inoculated with caprine herpesvirus alone or in non-infected controls. Pasteurella haemolytica was isolated from seven of eight lungs with pneumonia, but only from one of sixteen lungs without pneumonia. The lesions ranged from fatal acute exudative necrotising pneumonia to predominantly proliferative pneumonia. Half of the caprine herpesvirus-inoculated goats developed a clinical catarrhal rhinitis five days post-inoculation and the only virus-specific histopathological lesion was a mild tracheitis. Canine herpesvirus was recovered from the nasal swabs of all caprine herpesvirus- inoculated goats developed a clinical catarrhal rhinitis five days post-inoculation and the only virus-specific histopathological lesion was a mild tracheitis. Canine herpesvirus was recovered from the nasal swabs of all canine herpesvirus-inoculated goats and from the lungs of three goats inoculated with caprine herpesvirus alone. The experimental inoculations demonstrated that P. haemolytica alone can produce pneumonia in goats. In addition, the study showed that caprine herpesvirus readily proliferates in the upper respiratory tract and lungs of goats but the role of caprine herpesvirus in the aetiology of pneumonia remains uncertain.     

VACCINATION OF HEIFERS WITH A REDUCED DOSE OF BRUCELLA ABORTUS STRAIN 19 VACCINE BEFORE FIRST MATING

Ten Jersey heifers aged 14 to 23 months were vaccinated with 2.25 times 10⁸ cells of living Brucella abortus strain 19 vaccine. They and 10 similar non-vaccinated heifers were subsequently mated and when about 6 months pregnant were challenged by the conjunctival application of a virulent culture of B. abortus. The serological response to vaccination was much less than is usually seen following vaccination with the normal dose of strain 19, especially when the indirect haemolysis test was used. A persistent vaccinal reaction was observed in one heifer. Significant resistance to infection was demonstrated which was greater than that previously observed in calfhood vaccinates given the full dose but less than that shown by cows given the smaller dose in early pregnancy. The effectiveness of strain 19 vaccination appears to be related to the age of the animal at vaccination.     

Duration of immunity and efficacy of an oil emulsion Escherichia coli bacterin in cattle

An oil emulsion Escherichia coli bacterin administered in 1- and 2-dose vaccination regimens was evaluated in beef cattle. Serologic responses to the K99 pilus antigen were monitored, and suckling offspring from vaccinated and nonvaccinated cows were inoculated with virulent, K99-positive, enterotoxigenic Escherichia coli. The degree of protection and duration of immunity conferred were determined in 2 respective studies. In the first study (study A), titers of pregnant cattle were determined from time of vaccination through calving (a 6- to 20-week period). Titers of 24 cows vaccinated with a single 2-ml dose of bacterin were compared with those of 24 cows given a 2-dose regimen and with those of 23 nonvaccinated cattle (contemporary controls). Inoculum consisting of 1.2 X 10(12) viable enterotoxigenic E coli/dose administered to nursing calves from these dams yielded 0% mortality (0 deaths/20 calves) in calves from 1-dose vaccinates, 6% mortality (1 death/18 calves) in calves from 2-dose vaccinates, and 37% mortality (7 deaths/19 calves) in calves from nonvaccinated dams. Study B was an extended evaluation conducted in cattle that were kept in the study up to 87 weeks from initial vaccination until calving. Serologic titers to the K99 pilus antigen were compared in 1-dose, 2-dose, and nonvaccinated cattle in groups of 8, 6, and 6, respectively. Calves from these dams were inoculated with 8.1 X 10(11) viable enterotoxigenic E coli/dose, which resulted in 0% mortality (0 deaths/5 calves) in calves from 1-dose vaccinates, 0% mortality (0 deaths/5 calves) in calves from 2-dose vaccinates, and 80% mortality (5 deaths/6 calves) in calves from nonvaccinated dams.     

山羊痘灭活疫苗免疫保护试验

将山羊痘GT4-STV42-56种毒在犊牛睾丸细胞上繁殖,收获毒液,用0.1%甲醛溶液灭活,加适量206佐剂,制成山羊痘油佐剂灭活疫苗.将疫苗以不同剂量皮下免疫接种不同种群的山羊.免疫后21 d,用AV40株强毒进行攻毒保护试验.结果显示,免疫剂量达0.5 mL时,疫苗对内蒙绒山羊的保护率为100%,对广西黑山羊的保护率为80%.实验表明,山羊痘灭活疫苗对山羊的免疫效果确实可靠.     

Protection of ewes vaccinated with A22 strain Chlamydia psittaci (ovis) against challenge in pregnancy with homologous and heterologous strains of the organism

Fifty ewes were randomly divided into four groups. Groups A and B were vaccinated with an experimental vaccine derived from the A22 isolate of Chlamydia psittaci (ovis), an isolate known to cause ovine enzootic abortion (OEA). Groups C and D were unvaccinated controls. In mid-pregnancy, animals in group A and C were challenged with live A22 C. psittaci (ovis) and those in B and D were challenged with a field isolate of the organism (BS) against which the commercially available A22 vaccine appeared to offer poor protection. In group A, three animals showed clinical signs of OEA and six excreted chlamydiae. In group B, five ewes showed clinical signs of OEA and excreted chlamydiae. In group C, three ewes had clinical signs of OEA but seven excreted chlamydiae. In group D, all 11 ewes showed clinical signs of OEA and excreted chlamydiae in the products of parturition. This group produced only four live lambs with an average weight of viable lamb per ewe of 1.4 kg, whereas the other groups each produced 12 or 13 lambs with an average weight of viable lamb per ewe of more than 4 kg. The BS isolate was much more virulent than the A22 isolate for unvaccinated, pregnant ewes. However, the A22 vaccine offered significant protection against the heterologous BS isolate although on this occasion it did not appear to alter the course of disease produced by the less pathogenic A22 isolate.     

Mic1-3 Knockout Toxoplasma gondii is a good candidate for a vaccine against T. gondii-induced abortion in sheep

This study assessed the effectiveness of a mutant strain of Toxoplasma gondii (RH strain) lacking the mic1 and mic3 genes (Mic1-3KO) against Toxoplasma abortion in sheep. Ewes were inoculated subcutaneously with 10⁵ Mic1-3KO tachyzoïtes in three independent experiments. Following vaccination, Mic1-3KO induced a mild febrile response and serum IgG antibodies, which persisted throughout the experiments. Tissue cysts formed in the sheep, but were not, under our experimental conditions, infectious when given orally. Ewes were mated two months after vaccination and were orally challenged with the PRU strain of T. gondii at mid-gestation (400 oocysts in Experiments 1 and 2; 100 oocysts in Experiment 3). Challenge of vaccinated pregnant ewes resulted in a slight febrile response, whereas unvaccinated ewes developed a more severe, characteristic febrile response of longer duration. After challenge, all unvaccinated ewes aborted whereas 62%, 91% and 64% (Experiments 1, 2 and 3 respectively) of the lambs from vaccinated ewes were viable, with no clinical signs of infection. Mic1-3KO was as effective as S48, the strain used as a live vaccine for sheep (Toxovax^®). A dose of 10⁵ Mic1-3KO tachyzoites was sufficient to induce protection (versus a dose of 2 × 10⁶). Both subcutaneous and intraperitoneal injections were effective. Moreover, preliminary results showed the potential of Mic1-3KO to reduce the development of tissue cysts in lambs born to vaccinated ewes. This study demonstrates that Mic1-3KO is a potent vaccine candidate.