首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 31 毫秒
1.
Pseudorabies virus (PRV) antibodies, detectable by indirect radioimmunoassay (IRIA), serum-virus neutralization test (NT), or microimmunodiffusion test (MIDT) were developed within 8 days after pigs were inoculated with virulent PRV or attenuated PRV vaccine. Indirect radioimmunoassay and NT titers in pigs inoculated with virulent PRV were developed at the same rate, with IRIA titers being higher than NT titers. Pigs inoculated with attenuated or inactivated PRV vaccine developed peak mean prechallenge NT antibody titers of 4 and 1 (reciprocals of serum dilutions), respectively. Pigs inoculated with attenuated PRV vaccine had peak mean prechallenge IRIA antibody titers of 6, whereas pigs inoculated with inactivated PRV vaccine had mean IRIA antibody titers of 64. Challenge exposure of swine inoculated with attenuated or inactivated PRV vaccine elicited quantitatively equivalent responses, as measured by IRIA or NT, which were higher than prechallenge titers. There were no false-positive IRIA, NT, or MIDT results obtained when sera from nonvaccinated, nonchallenge-exposed pigs were tested. It appears that the PRV infection status of a seropositive swine herd could be ascertained by serologically monitoring several representative animals from a herd, using the NT. If 2 or more tests of representative animals at 14-day intervals were done and the mean NT titer was 4 or less, it could be concluded that the herd was vaccinated against, but not infected with, virulent virus.  相似文献   

2.
Evaluation in swine of a subunit vaccine against pseudorabies   总被引：2，自引：0，他引：2  
A subunit vaccine against pseudorabies virus (PRV) was prepared by treating a mixture of pelleted virions and infected cells with the nonionic detergent Nonidet P-40 and emulsifying the extracted proteins incomplete Freund's adjuvant. Three 7-week-old pigs without antibodies against PRV were given 2 IM doses of this vaccine 3 weeks apart. Thirty days after the 2nd vaccination, 10(6) median tissue culture infective doses (TCID50) of a virulent strain of PRV were administered intranasally. Tonsillar and nasal swabs were collected daily between 2 and 10 days after challenge exposure. The pigs vaccinated with the subunit vaccine were not found to shed virulent PRV. Two groups of five 7-week-old pigs vaccinated with commercially available vaccines, either live-modified or inactivated virus, and subsequently exposed to 10(6) TCID50 of virulent PRV, shed virulent virus for up to 8 days. The subunit vaccine induced significantly higher virus-neutralizing antibody titers than either the live-modified or inactivated virus vaccine.  相似文献   

3.
Inactivated canine parvovirus (CPV) and inactivated feline panleukopenia virus (FPV) vaccines were evaluated in dogs. Maximal serologic response occurred within 1-2 weeks after vaccination. Antibody titers then declined rapidly to low levels that persisted at least 20 weeks. Immunity to CPV, defined as complete resistance to infection, was correlated with serum antibody titer and did not persist longer than 6 weeks after vaccination with inactivated virus. However, protection against generalized infection was demonstrated 20 weeks after vaccination. In unvaccinated dogs, viremia and generalized infection occurred after oronasal challenge with virulent CPV. In contrast, viral replication was restricted to the intestinal tract and gut-associated lymphoid tissue of vaccinated dogs. Canine parvovirus was inactivated by formalin, beta-propiolactone (BPL), and binary ethylenimine (BEI) in serum-free media; inactivation kinetics were determined. Formalin resulted in a greater loss of viral HA than either BEI of BPL, and antigenicity was correspondingly reduced.  相似文献   

4.
Knowledge of the dose-response relation of inactivated vaccines and of the factors that influence this relation is essential for the evaluation of existing vaccine potency assays and the development of new potency assays that are based on the antigen content of the inactivated vaccines. We quantified the relation between vaccine dose, serologic response, and clinical protection after vaccination for three different inactivated Newcastle disease (ND) vaccines. Qualitatively, similar dose-response curves were obtained for the three vaccines when either the serologic response or the clinical protection of specific-pathogen-free (SPF) chickens was plotted against the different vaccine doses applied. However, the vaccines differed quantitatively: doses of vaccines that induced similar antibody titers or clinical protection differed 2-8-fold. In contrast with the narrow range of antibody titers induced by a full vaccine dose, a very broad range of titers was obtained after dilution of the vaccines. At least 95% of the SPF chickens with detectable antibody in the serum were protected against a challenge with virulent Herts ND virus. The relation between the dosage of two different ND vaccines and the serum antibody titers remained markedly constant between 3 and 18 wk after vaccination. Vaccination of broilers instead of layers with a dilution series of inactivated ND vaccine resulted in significantly lower antibody levels and less clinical protection against virulent challenge. In conclusion, despite quantitative differences, we found comparable dose-response relations for the three inactivated ND vaccines studied.  相似文献   

5.
Protection provided by live and inactivated virus vaccination against challenge with the virulent nephropathogenic infectious bronchitis virus (NIBV) strain PA/Wolgemuth/98 was assessed. Vaccinations with combinations of live attenuated strains Massachusetts (Mass) + Connecticut (Conn) or Mass + Arkansas (Ark) were given by eyedrop to 2-wk-old specific-pathogen-free leghorn chickens. After live infectious bronchitis virus (IBV) vaccination, some chickens at 6 wk of age received an injection of either an oil emulsion vaccine containing inactivated IBV strains Mass + Ark or an autogenous vaccine prepared from NIBV PA/Wolgemuth/98. Challenge with PA/Wolgemuth/98 was given via eyedrop at 10 wk of age. Serum IBV enzyme-linked immunosorbent assay antibody geometric mean titers (GMTs) after vaccination with the combinations of live attenuated strains were low, ranging from 184 to 1,354, prior to NIBV challenge at 10 wk of age. Both inactivated vaccines induced an anamnestic response of similar magnitudes with serum GMTs of 6,232-12,241. Assessment of protection following NIBV challenge was based on several criteria virus reisolation from trachea and kidney and renal microscopic pathology and IBV-specific antigen immunohistochemistry (IHC). Live attenuated virus vaccination alone with combinations of strains Mass + Conn or Mass + Ark did not protect the respiratory tract and kidney of chickens after PA/Wolgemuth/98 challenge. Chickens given a live combination vaccination of Mass + Conn and boosted with an inactivated Mass + Ark vaccine were also susceptible to NIBV challenge on the basis of virus isolation from trachea and kidney butshowed protection on the basis of renal microscopic pathology and IHC. Live IBV-primed chickens vaccinated with an autogenous inactivated PA/Wolgemuth/98 vaccine had the highest protection against homologous virulent NIBV challenge on the basis of virus isolation.  相似文献   

6.
The antibody response of cattle to bovine respiratory syncytial virus (BRSV) immunization was investigated using 4 different commercially available mixed vaccines. Forty, 5-6 month old, beef calves, randomly assigned to groups of 10, were vaccinated on day 0 and 21 with 1 of 3 inactivated vaccines, (3 groups), or a modified live virus (MLV) vaccine. BRSV-specific antibody responses were measured prior to vaccination and on day 35 by using an enzyme linked immunosorbent assay (ELISA), virus neutralization assay (VN), a fusion inhibition assay (FI); and responses were also measured for their ability to facilitate antibody dependent, complement mediated cytotoxicity (ADCMC) of BRSV infected cells. Sera from day 35 were, in addition, analyzed by use of an IgG1, IgG2 isotype specific ELISA. All vaccines induced significant increases in BRSV specific IgG antibody as measured by ELISA, but only one inactivated and the MLV vaccine induced significant increases in VN titers. Fusion inhibiting antibody titers were low or undetected in calves vaccinated with the inactivated vaccines. Vaccination with modified live virus induced significantly higher titers of fusion inhibiting antibodies, which are considered to be most highly correlated with protection. The VN to ELISA and FI to ELISA ratio of the calves that received MLV vaccine were significantly greater than the calves receiving the 3 inactivated vaccines. Vaccination with MLV induced the highest IgG2/IgG1 ratio. This difference was small, and only significant relative to 2 of the inactivated vaccine groups, which were not significantly different from each other. The higher proportion of IgG2 isotype in the MLV sera was not associated with lower ADCMC, a function not attributed to this isotype. The VN and FI titers, but not the ELISA value of the sera, were most predictive of ADCMC. The inactivation processes apparently alter epitopes and affect the induction of functional antibodies.  相似文献   

7.
One month prior to breeding, sows were vaccinated with an attenuated pseudorabies virus vaccine or challenged with a field strain of pseudorabies virus. A third group of sows were not vaccinated or challenged before breeding. Pigs from these sows were vaccinated at 3, 6, or 12 weeks of age and challenged with virulent virus three weeks later. One pig from each litter served as an unvaccinated, unchallenged control. Serum neutralization titers of these pigs were monitored from birth until 22 weeks of age. Titers of the sows were monitored through breeding, gestation and farrowing. The maximum prefarrowing anti-pseudorabies virus titer in the field virus challenged sows occurred four weeks following challenge. A significant decline in titers occurred at farrowing. Titers rose from one week postfarrowing and then declined. Titers in the field virus infected sows were consistently two to threefold greater than those of the vaccinated sows. The maximum prefarrowing anti-pseudorabies virus titer in the vaccinated sows occurred six weeks following vaccination. The geometric mean titer in these sow's then decreased and increased for two weeks after farrowing. The results in the pigs can be summarized as follows: Pigs from control sows had a greater serological response following field virus challenge than following vaccination with a modified live virus. Pigs from control sows responded serologically to vaccination at 3, 6 and 12 weeks of age. Pigs from control sows which were challenged at 6, 9 and 15 weeks of age had similar antibody responses. Pigs from vaccinated sows had no increase in titer following vaccination at three and six weeks of age. Titers increased when these pigs were vaccinated at 12 weeks of age. There was no significant increase in mean titers of pigs from challenged sows following vaccination at 3, 6 and 12 weeks of age. Vaccinated pigs from control and vaccinated sows had a secondary response following challenge three weeks after vaccination.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

8.
The humoral antibody response of pseudorabies-immune pigs to reactivation of latent pseudorabies virus (PRV) was compared with the response following direct exposure to virulent PRV. Nine pigs that had been vaccinated for pseudorabies and later exposed to virulent virus to establish latent infection were given dexamethasone to reactivate latent virus (3 pigs), were exposed oronasally and parenterally to virulent virus (3 pigs), or were kept as nontreated controls (3 pigs). Sera collected from all 9 pigs just before and 3 weeks after treatment were tested by virus neutralization and radioimmunoprecipitation. The 3 pigs exposed directly to virulent virus and 2 of the 3 pigs given dexamethasone had a 4-fold or greater increase in neutralizing antibody titer. All 6 of these pigs had an increase in precipitating antibody activity. Precipitation patterns changed both quantitatively and qualitatively, especially for virus-coded proteins of relatively low molecular weight (less than 46 K). There were some differences in the precipitation patterns associated with sera of individual pigs. However, there was no clear indication of any difference between the 2 treatment groups and therefore no evidence that reactivation of latent virus is associated with any unique immunologic response that could be detected by radioimmunoprecipitation and used diagnostically. Clinical signs were limited to the 3 pigs that were exposed oronasally and parenterally to virulent virus even though the dexamethasone-treated pigs shed more virus for much longer than did those exposed directly to virus.  相似文献   

9.
Antibody responses were compared in guinea-pigs, rabbits and pigs following vaccination with inactivated porcine parvovirus (PPV) vaccines. Mean PPV hemagglutination inhibition (HI) antibody titers of 52, 56 and 36 at 1 week after first vaccination and 896, 640 and 512 at 2 weeks after second vaccination were detected in guinea-pigs, rabbits and pigs, respectively. PPV vaccines prepared with greater concentrations of virus, as determined by hemagglutination (HA) units, and of aluminum hydroxide gel adjuvant, induced higher HI antibody titers in guinea-pigs. Optimal concentrations for inducing consistently high antibody titers consisted of vaccine virus with a HA titer of 256/0.1 ml and gel adjuvant at a final concentration of 50%. A second vaccination at 4 weeks compared to 2 or 3 weeks after first vaccination resulted in higher mean HI titers. These data provide preliminary information on the use of guinea-pigs or rabbits as laboratory animal models for testing the potency of PPV vaccines.  相似文献   

10.
The ability of pseudorabies virus (PRV) to infect and establish latency in pigs with passively acquired (maternal) antibody for PRV was tested by exposing such pigs to the virus and subsequently attempting to reactivate latent virus by administering large doses of dexamethasone. Pigs of each of 4 litters that had nursed gilts with relatively high (512, gilts 1 and 2), moderate (32, gilt 3), and no (less than 2, gilt 4) serum titers of virus-neutralizing (VN) antibodies for PRV were allotted to 3 treatment groups (A, B, C) when they were 2 weeks old. Group-A pigs were separated from littermates and dam and thereafter kept in isolation; group-B pigs were experimentally exposed oronasally to PRV and 1 hour later returned to their dam; group-C pigs were kept with their dam and potentially exposed to PRV by contact with littermates of group B. Sera obtained from pigs at selected intervals until they were 17 weeks old were tested for VN activity and for precipitating activity for radiolabeled viral proteins. All group-A pigs remained clinically normal throughout the experiment. Depending on the initial amount of passively acquired antibody, little or no serum VN or precipitating activity remained by the time these pigs were 17 weeks old. Group-B and -C pigs, with relatively high amounts of passively acquired antibody when exposed to PRV, also remained clinically normal. However, most became latently infected as subsequently evidenced by either dexamethasone-induced or noninduced virus reactivation. Noninduced reactivation may have been initiated by weaning the pigs when they were about 8 weeks old.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

11.
Intranasal (IN) vaccination of pigs with low levels of maternally-derived antibody (MDA) has previously been shown to confer good protection against challenge with virulent Aujeszky's disease virus (ADV). The objective of the present study was to determine the efficacy of IN vaccination with an attenuated ADV, in comparison with that of an inactivated vaccine given parenterally, in pigs with higher MDA titres at the time of vaccination. In one experiment, vaccinations were done at 6 weeks of age, and in another experiment pigs were vaccinated at 4 and/or 9 weeks of age. Two months after (the last) vaccination pigs were challenged intranasally with a virulent ADV. Protection was evaluated on the basis of mortality, periods of growth arrest, fever and virus shedding after challenge. The presence of MDA markedly depressed the serum-neutralizing antibody response after vaccination. Sensitisation occurred after parenteral vaccination with an inactivated vaccine despite high MDA levels. Although the intranasally-vaccinated pigs had lower levels of neutralizing antibody at the time of challenge, they were significantly better protected than pigs given 1 or 2 doses of the inactivated vaccine. Comparing the present results with those of a previous study, it appears that the efficacy of parenteral as well as intranasal ADV vaccination decreases with increasing levels of MDA at the time of vaccination.  相似文献   

12.
Different deleted Aujeszky's disease vaccines were compared for their ability to induce an immunity which suppresses virus excretion optimally upon infection. Groups of pigs were vaccinated once with attenuated deleted Aujeszky's disease vaccine (gI, gX or gp63 negative), suspended in phosphate buffered saline. Two additional groups were vaccinated with a gI deleted vaccine virus suspended in an oil-in-water emulsion. Other groups were vaccinated twice with gI deleted inactivated vaccines. The three control groups included were: pigs immune after infection, unvaccinated pigs and pigs receiving vaccine without known deletion in the envelope. Experimental challenge took place 3 or 4 weeks after the only or the last vaccination. The number of excreting pigs, the duration of excretion and the virus titers excreted, were determined for all the groups. All the pigs vaccinated with glycoprotein deletion vaccines suspended in phosphate buffered saline, excreted virus for 2 to 6 days after challenge. A 100 to 1000 fold reduction in excreted virus titers was obtained in vaccinated pigs compared to unvaccinated ones. Some vaccines suppressed virus excretion better than others, but no correlation could be made between the type of deletion (gI, gX or gp63) and the degree of reduction in virus excretion. Similar results were obtained with two applications of inactivated vaccines. The lowest number of excreting pigs, the lowest duration of excretion and the lowest titers were obtained in groups vaccinated with the attenuated vaccine suspended in an oil-in-water emulsion. No vaccine suppressed virus excretion totally.  相似文献   

13.
Groups of pigs vaccinated with an inactivated bivalent vaccine containing porcine parvovirus (PPV) and pseudorabies virus (PRV) developed geometric mean titers (GMT) of humoral antibody for each of the viruses as high or slightly higher than those of other groups of pigs that were vaccinated with inactivated monovalent vaccines containing one or the other of the same viruses. An increase in GMT after challenge exposure of vaccinated pigs to live virus indicated that vaccination did not prevent virus replication. However, an indication that replication was less extensive in vaccinated pigs was provided by the following. Although neither vaccinated nor nonvaccinated (control) pigs had clinical signs after exposure to the live PPV, the effect of vaccination was evident by the fact that GMT were higher in nonvaccinated pigs after exposure than they were in vaccinated pigs. Conversely, all pigs exposed to live PRV had clinical signs, but these signs varied between mild-to-moderate and transient for vaccinated pigs to severe and fatal for nonvaccinated pigs.  相似文献   

14.
A latent pseudorabies virus infection was established in pigs despite vaccination with a modified-live pseudorabies virus vaccine. Although the vaccinated pigs developed high concentrations of antibody, virus was recovered from the tonsils and lungs of pigs treated with dexamethasone three months after inoculation with virulent virus. These results may explain why vaccination programs have failed to eliminate the persistence and spread of virulent pseudorabies virus in infected herds.  相似文献   

15.
The K strain of Aujeszky's disease virus (ADV) grown in Vero cells was used to vaccinate pigs. Following intramuscular inoculation, the pigs remained healthy, no vaccine virus was excreted and virus could be detected only at the inoculation site. One inoculation gave good protection against challenge with a virulent strain of ADV, and the amount of virulent ADV excreted was geatly curtailed. Following vaccination only low leads of serum neutralizing antibody were detected (geometric mean titre 1/2), but three weeks after challenge very high levels were found (GMT 1/1773). Intranasal vaccination gave similar results. There was minimal excretion of vaccine virus. The clinical reaction on challenge was less severe than in the intramuscularly challenged group, although lower antibody levels were detected three wekks following challenge (GMT 1/483). A field trial, using this strain given subcutaneously, indicated that one inoculation of this vaccine is effective.  相似文献   

16.
Broiler chickens were vaccinated at 18 days of age against infectious laryngotracheitis (ILT) using chicken-embryo-origin (CEO) and tissue-culture-origin (TCO) vaccines, each vaccine given either by drinking water, spray, or eyedrop. Controls were not vaccinated. The broilers were challenged 3 weeks later with virulent ILT virus (USDA challenge strain). Serum samples taken before challenge were analyzed by a virus neutralization (VN) test to determine titers due to vaccination. Both vaccines, regardless of route of administration, produced low VN titers, geometric mean titer (GMT) being less than 4.0 in all vaccinated groups. When administered by the same route, the CEO vaccine produced higher titers than the TCO vaccine. Titers following drinking-water or eyedrop administration of vaccines were higher than titers following spray vaccination. There was an inverse relationship between pre-challenge VN titers of groups of birds and the percentage of birds in the groups dying from ILT virus challenge. The drinking-water route of vaccination provided the most protection, while the spray provided the least.  相似文献   

17.
We compared the efficacy of 3 commercial vaccines against swine influenza A virus (SIV) and an experimental homologous vaccine in young pigs that were subsequently challenged with a variant H3N2 SIV, A/Swine/Colorado/00294/2004, selected from a repository of serologically and genetically characterized H3N2 SIV isolates obtained from recent cases of swine respiratory disease. The experimental vaccine was prepared from the challenge virus. Four groups of 8 pigs each were vaccinated intramuscularly at both 4 and 6 wk of age with commercial or homologous vaccine. Two weeks after the 2nd vaccination, those 32 pigs and 8 nonvaccinated pigs were inoculated with the challenge virus by the deep intranasal route. Another 4 pigs served as nonvaccinated, nonchallenged controls. The serum antibody responses differed markedly between groups. After the 1st vaccination, the recipients of the homologous vaccine had hemagglutination inhibition (HI) titers of 1:640 to 1:2560 against the challenge (homologous) virus. In contrast, even after 2nd vaccination, the commercial-vaccine recipients had low titers or no detectable antibody against the challenge (heterologous) virus. After the 2nd vaccination, all the groups had high titers of antibody to the reference H3N2 virus A/Swine/Texas/4199-2/98. Vaccination reduced clinical signs and lung lesion scores; however, virus was isolated 1 to 5 d after challenge from the nasal swabs of most of the pigs vaccinated with a commercial product but from none of the pigs vaccinated with the experimental product. The efficacy of the commercial vaccines may need to be improved to provide sufficient protection against emerging H3N2 variants.  相似文献   

18.
The objective of this study was to determine whether a commercially available, saponin-adjuvanted, inactivated bovine respiratory syncytial virus (BRSV) vaccine would protect calves from experimental infection with virulent BRSV. This was a randomized controlled trial comprising 14, 8- to 9-week-old calves seronegative for BRSV Group 1 calves (n = 8) were not vaccinated and group 2 calves (n = 6) were vaccinated on days 0 and 19 with an inactivated BRSV vaccine. All calves were challenged with virulent BRSV on day 46. Clinical signs, arterial PO2, and immune responses were monitored after challenge. Calves were euthanatized on day 54 (8 d after challenge) and lungs were examined for lesions. Vaccination elicited increases in BRSV-specific immunoglobulin (Ig) G and virus neutralizing antibody titers. Challenge with BRSV resulted in severe respiratory tract disease and extensive pulmonary lesions in control calves, but no signs of clinical disease and minimal or no pulmonary lesions in vaccinated calves. Arterial blood oxygen values on day 53 (7 d after challenge) in control calves were significantly lower than those in vaccinated calves, which remained within normal limits. Control calves shed BRSV for several days after challenge, whereas BRSV was not detected on deep nasal swabs from vaccinated calves. In summary, the results indicated that this inactivated BRSV vaccine provided clinical protection from experimental infection with virulent virus 27 d after vaccination and significantly decreased the prevalence and severity of pulmonary lesions. Efficacy was similar to that reported for other commercial inactivated and modified-live BRSV vaccines.  相似文献   

19.
In order to potentiate the low immunogenicity of the inactivated Newcastle disease virus immunized into chickens by mucosal route, liposomes as a drug delivery system and LPS (lipopolysaccharide) as an immuno-stimulator were evaluated. Here, we report a new nasal delivery system of inactivated Newcastle disease virus (NDV) vaccine. The intranasal vaccine was based on different lipids to form MLV (multi-lamellar vehicles) liposomes. The liposomes had combined carrier and adjuvant activities, which induced strong systemic (serum) and local (lung and nasal) humoral responses in SPF (specific-pathogen-free) chickens, and provided protective immunity. PC-Lip (phosphatidylcholine-liposome) elicited significant mucosal secretary immunoglobulin A (s-IgA) levels (p < 0.05) in tracheal lavage fluid and serum IgG levels (p < 0.05). In response to virulent viral challenge, birds treated with PBS (phosphate buffered saline) as control group died, whereas 80% of chickens which received PC-Lip, PC-Lip-LPS, PS-Lip (phosphatidylserine-liposome), and PS-Lip-LPS survived. HAI titers were 1:2560 in the PS-Lip-LPS group and 1:1280 in the PC-Lip, PC-Lip-LPS, and PS-Lip groups after two vaccinations. The results suggest that PC-Lip or PS-Lip might thus be suitable as a potential adjuvant for mucosal vaccination against NDV in chickens.  相似文献   

20.
OBJECTIVE: To evaluate duration of immunity in cats vaccinated with an inactivated vaccine of feline panleukopenia virus (FPV), feline herpesvirus (FHV), and feline calicivirus (FCV). ANIMALS: 17 cats. PROCEDURE: Immunity of 9 vaccinated and 8 unvaccinated cats (of an original 15 vaccinated and 17 unvaccinated cats) was challenged 7.5 years after vaccination. Specific-pathogen-free (SPF) cats were vaccinated at 8 and 12 weeks old and housed in isolation facilities. Offspring of vaccinated cats served as unvaccinated contact control cats. Virus neutralization tests were used to determine antibody titers yearly. Clinical responses were recorded, and titers were determined weekly after viral challenge. RESULTS: Control cats remained free of antibodies against FPV, FHV, and FCV and did not have infection before viral challenge. Vaccinated cats had high FPV titers throughout the study and solid protection against virulent FPV 7.5 years after vaccination. Vaccinated cats were seropositive against FHV and FCV for 3 to 4 years after vaccination, with gradually declining titers. Vaccinated cats were protected partially against viral challenge with virulent FHV. Relative efficacy of the vaccine, on the basis of reduction of clinical signs of disease, was 52%. Results were similar after FCV challenge, with relative efficacy of 63%. Vaccination did not prevent local mild infection or shedding of FHV or FCV. CONCLUSIONS: Duration of immunity after vaccination with an inactivated, adjuvanted vaccine was > 7 years. Protection against FPV was better than for FHV and FCV. CLINICAL IMPLICATIONS: Persistence of antibody titers against all 3 viruses for > 3 years supports recommendations that cats may be revaccinated against FPV-FHV-FCV at 3-year intervals.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号