Duration of immunity in dogs vaccinated against leptospirosis with a bivalent inactivated vaccine

Duration of immunity in dogs induced with current commercial inactivated leptospirosis vaccines and evaluated against experimental infection, to date, has hardly been documented. The purpose of the present work was to assess the duration of immunity in dogs that is attainable with a commercial inactivated bivalent leptospirosis vaccine. For this purpose, young dogs were vaccinated twice followed by challenge with either Leptospira interrogans serovar canicola or L. interrogans serovar icterohaemorrhagiae 5 weeks, 27 weeks or 56 weeks after the second vaccination. For assessment of the duration of immunity, titres of agglutinating serum antibodies were measured before and after challenge, and the effects of challenge on a variety of parameters were determined including reisolation of challenge organisms from blood, urine and kidney. Both challenge strains induced a generalised infection in control dogs, the canicola strain being most virulent. From the results with different parameters it appeared that the two vaccinations induced a high rate of protection from generalised infection with canicola and icterohaemorrhagiae at 5, 27 and 56 weeks after the second vaccination. In addition, after 56 weeks, still a high level of immunity against renal infection with sv. canicola and, as a consequence, urinary shedding of sv. canicola bacteria, was demonstrated. It was, therefore, concluded that with this vaccine, using this vaccination schedule, a duration of immunity of 1 year can be attained against infection with both serovars.     

Long-term follow-up study of cats vaccinated with a temperature-sensitive feline infectious peritonitis vaccine.

The long-term safety of a temperature-sensitive feline infectious peritonitis (FIP) vaccine was evaluated. Five hundred eighty-two healthy cats of various age groups were vaccinated with 2 doses of the vaccine. Seventy-eight percent, or 453 cats, were available for follow-up. The mean follow-up period was 541 days. At the end of the follow-up period, 427 cats (94%) were alive. FIP was not diagnosed in any cat during the follow-up period, but 1 cat died of FIP after completion of the follow-up period. Fifty cats (11%) presented with a problem during the follow-up period, but there were typical of those seen in a feline practice. The temperature-sensitive FIP vaccine appears to be safe for use in the general cat population. It does not appear to sensitize cats to develop FIP, nor do there appear to be any other systemic problems associated with use of the vaccine.     

Efficacy of trivalent inactivated encephalomyelitis virus vaccine in horses

Twenty-nine horses were vaccinated with a trivalent (Venezuelan, eastern, and western) inactivated equine encephalomyelitis virus vaccine. The vaccine purchased for this study was the only one licensed and commercially available in May, 1975. Plaque-neutralizing and hemagglutinin-inhibiting antibodies in response to each of the 3 equine encephalomyelitis viruses were determined after vaccination. Horses had rising levels of plaque-neutralizing and hemagglutinin-inhibiting antibodies shortly after injection with the 1st and 2nd doses of the vaccine (given 3 weeks apart) and were refractory to challenge of immunity with virulent homologous virus at 3, 8, and 12 months after vaccination. After 12 months, 8 horses were revaccinated; maximum antigenic stimulation was achieved with the 1st dose of the 2nd series of vaccinations.     

Duration of immunity in foxes vaccinated orally with ERA vaccine in a bait.

Red foxes (Vulpes vulpes) vaccinated orally with the ERA strain of rabies vaccine in a bait were challenged after 83 mo. Ten of 11 foxes that had seroconverted following vaccination resisted challenge with a virulent rabies virus which produced clinical signs of rabies in 6 of 6 unvaccinated foxes. Five of 11 vaccinated animals retained titers of rabies virus neutralizing antibody throughout the period. Although 6 of 11 had no detectable antibody at the time of challenge, 5 of these 6 resisted challenge and had an anamnestic response, as indicated by elevated titers of antibody when measured at day 77 postchallenge. These results show that foxes can be immunized successfully with a single oral dose of ERA vaccine, probably with protection against a lethal rabies challenge, for at least 7 y.     

Investigation of antigen specific lymphocyte responses in healthy horses vaccinated with an inactivated West Nile virus vaccine

West Nile virus (WNV) is a single-stranded, enveloped RNA virus capable of causing encephalitic disease in horses. Unvaccinated horses are at risk for developing WNV disease in endemic geographic regions. Effective vaccination reduces disease frequency and diminishes disease severity in vaccinated individuals that become infected with WNV. Recent data indicate CD4+ lymphocytes are required for effective protection against disease; in particular, cross talk between CD4+ and CD8+ lymphocytes must be functional. The objective of this project was to investigate immune responses in horses throughout a series of three vaccinations using a commercial inactivated vaccine under natural conditions. Immune responses to vaccination were determined by neutralizing antibody titers with plaque reduction neutralization test (PRNT), IgM titer (capture ELISA), WNV specific antibody Ig subclass responses, WNV lymphocyte proliferative responses and intracellular cytokine expression. Horses were vaccinated with a series of three vaccines at 3-week intervals using an inactivated product. An initial measure of immune activation following vaccination was determined by evaluating changes in lymphocyte cytokine expression. Interferon (IFN) gamma and interleukin (IL)-4 expressing CD4+ lymphocytes significantly increased 14 days following initial vaccination compared to unvaccinated horses (P<0.05). IFN-gamma expressing CD8+ lymphocytes also increased and remained elevated for 110 days. Antigen specific lymphocyte proliferative responses were significantly increased up to 90 days following the third vaccination (P<0.05). As expected, vaccinated horses produced increased neutralizing antibody based on PRNT data and WNV antigen-specific Ig subclass responses compared with unvaccinated horses (P<0.05). Our data indicate that WNV vaccination with an inactivated product effectively induced an antigen-specific antibody responses, as well as CD4+ and CD8+ lymphocyte activation.     

Vaccination of swine with an inactivated porcine parvovirus vaccine in the presence of passive immunity

A study was conducted to determine whether low hemagglutination inhibiting (HI) titers (1:5) for porcine parvovirus (PPV) block the development of immune response to a PPV vaccine. Pigs with low (1:5), medium (1:10 or 1:20), or high (1:40 or 1:80) titers were obtained by IV injections with various amounts of PPV immune serum. Pigs were inoculated with 1 or 2 doses of vaccine and were monitored for serum HI antibodies to PPV. Pigs with low titers responded to vaccine just as well as did the seronegative pigs. The HI titers of pigs with medium titers did not increase after first vaccination. After the second vaccination, however, their titers increased and were similar to those of pigs with low titers. High titers blocked the response to vaccination. The pigs that received 2 doses of vaccine had higher titers than did those of pigs that received 1 dose of vaccine. The results indicated that low titers, which would be expected in gilts at the time of vaccination, do not interfere with immunization by the inactivated PPV vaccine, and that 2 doses of vaccine may provide better and longer lasting immune response to inactivated PPV vaccine and probably longer lasting immunity against PPV-induced reproductive failure.     

Detection of African horsesickness (AHS) in recently vaccinated horses with inactivated vaccine in Qatar

Two 7-year old Arabian racing horses were reported to show typical AHS symptoms in Qatar and died shortly after. The horses had been vaccinated with formol inactivated vaccine approximately 10 days before the onset of the disease. Blood samples from these horses were collected and AHS virus isolated from one sample after intracerebral (i.c.) inoculation into suckling mice. The virus identity was confirmed by complement fixation test (CFT) using the virus antigen and reference type 9 of AHS virus hyperimmune serum. The serotype of the isolated virus was identified by serum neutralization test (SNT) using reference types of AHS virus. Two possibilities of the original source of this infection were suggested. The infection might be due first to the natural endemic occurrence of the virus in the country and secondly, to the presence of residual infectious virus in the inactivated vaccine.     

猪链球菌多价灭活疫苗安全性和免疫原性试验

猪的链球菌感染已成为世界性的猪传染病。在国外 ,多由 D群链球菌的某些血清型特别是 2型猪链球菌 (Streptococci suis)引起猪的败血型和脑炎型链球菌病 [2、3、6、7、8]。而在国内对猪链球菌致病菌的研究证实 ,以 C群的兽疫链球菌为主 ,D群较少[1、4、5] ,E群链球菌则引起慢性链球菌病的关节炎和淋巴结炎 (脓肿 ) [2 ] 。近几年来我们发现 ,有些猪场对各类猪群均进行过链球菌苗的接种 ,但仍然大批发生链球菌病 ,造成大量死亡 ,后来经过对分离的致病菌作分群鉴定 ,同时对发病猪群采血检测群特异性抗体 ,结果发现免疫的疫苗抗原的菌群与当…     

猪蓝耳病灭活疫苗与弱毒疫苗免疫后的抗体水平比较

为比较猪蓝耳病灭活疫苗与弱毒疫苗的免疫抗体水平,本试验在惠城区某猪场随机选取100头仔猪,分成两组,分别免疫猪蓝耳病灭活疫苗与弱毒疫苗,采用ELISA方法检测血清中的抗体水平,并对两组抗体的S/P值进行比较。结果表明,猪蓝耳病弱毒疫苗产生的抗体水平比灭活疫苗高,灭活疫苗免疫效果较差,且抗体持续时间短。本研究为猪场蓝耳病的防控及免疫程序的制定提供参考依据。     

Duration of immunity induced in chickens by an attenuated live Salmonella enteritidis vaccine and an inactivated Salmonella enteritidis/typhimurium vaccine

The aim of this study was to examine the duration of immunity of different vaccination schemes using the S. enteritidis live vaccine Gallivac Se and the S. enteritidis-S. typhimurium inactivated vaccine Gallimune Se+St. Three groups of Lohman Brown chickens were used. Group one was vaccinated three times orally with Gallivac Se at weeks one, seven and 13 of age. Group two was vaccinated twice orally with Gallivac Se in weeks one and seven and once i.m. with Gallimune Se+St in week 14 of age. A third group was not vaccinated and served as the control group. Eight randomly selected chickens from each of the three groups were challenged with a nalidixic acid resistant S. enteritidis PT4 strain in weeks 24, 51 and 71 of age and the same number of animals were challenged with a S. typhimurium DT 104 strain in weeks 26, 54 and 73 (75) of age.The chickens were euthanised seven days post challenge and the number of challenge strain organisms (log10 cfu) in the liver and on caecal mucosa was determined.The quantitative investigation of the challenge strain in the liver and caecal mucosa revealed a statistically significant (p < 0.05) lower challenge strain burden in the vaccinated groups compared with the non-vaccinated control group up to week 71 (73) of age. The protective effects were demonstrated for both challenge strains.     

The anamnestic serologic response to vaccination with a canarypox virus-vectored recombinant West Nile virus (WNV) vaccine in horses previously vaccinated with an inactivated WNV vaccine

A new recombinant West Nile virus (WNV) vaccine has been licensed for use in horses. Prior to the availability of the recombinant vaccine in 2004, the only equine WNV vaccine available on the market had been an inactivated vaccine. Since the recombinant vaccine only expresses selected viral genes, the question could be posed as to whether a single dose of the recombinant vaccine would be effective in producing an anamnestic serologic response in horses previously vaccinated with an inactivated WNV vaccine. In this study we demonstrate that vaccination of horses with a canarypox-vectored recombinant vaccine, under field conditions, results in a marked anamnestic response in horses previously vaccinated with an inactivated WNV vaccine.     

Experiements with an inactivated hepatitis leptospirosis vaccine in vaccination programmes for dogs.

A fluid adjuvanted vaccine consisting of inactivated hepatitis virus (iH) and leptospirae antigens (L) was developed. The vaccine (Kavak iHL; Duphar) was tested in several vaccination programmes both alone and in combination with freeze dried measles (M) or distemper (D) vaccines. The results demonstrate that this new vaccine is also effective in pups with maternally derived antibodies, although a second vaccination at 14 weeks of age is recommended to boost the first vaccination. For the booster vaccination either the iHL-vaccine or the liver attenuated hepatitis vaccine (H) can be used.