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1.
We analysed genogroups of four feline calcivirus (FCV) isolates (FCV-S, H10, Ao198-1 and ML89) obtained from cats that experienced FCV infection after having been vaccinated against FCV. New PCR primer sets (8F/8R, Ao-S/Ao-A, cp-S/cp-A) were also designed, since the conventional Seal primer failed to amplify the target sequences in two samples. The genogroups of the four isolates as well as eight global and 17 domestic strains were determined by phylogenetic analysis of their amino acid sequences. One out of the four strains (25%) isolated in this study, H10, was grouped into genogroup I, along with the vaccine strains F9 and FCV-255. The other three isolates (75%) belonged to genogroup II. Thus, there were more isolates in genogroup II than in genogroup I. However, the antibody values of the four isolates against cat anti-F9 antisera were significantly decreased. There may be no relationship between the neutralizing antibody titre and genogroup. Amino acid sequence alignment of the four isolates showed that only a single amino acid in region C, which is involved in neutralization epitopes, was different in ML89 strain from that of F9. The other three strains, H10, Ao198-1 and FCV-B, shared the same amino acid sequence with F9. Alignment of amino acids for linear epitopes in the F9 strain, which are located at regions D and E, showed variations in 5' hypervariable region (HVR) of E, whereas D and conE had only synonymous substitutions i.e. no change in the amino acid sequence. This mutation in 5' HVR of region E suggested a vaccine breakdown, as the region is known to be essential for antigenicity. The genogroup II FCV is likely to be the cause of the FCV infection in this study, while the vaccine strains belong to genogroup I. Thus, the existing vaccine may need reevaluation for its effectiveness.  相似文献   

2.
Feline calicivirus (FCV) comprises a large number of strains which are related antigenically to varying degrees. The antigenic variability creates problems for choosing antigens to include in vaccines. Historically, these have been selected for use based on their cross-reactivity with a high proportion of field strains. However, it is important to determine the current level of cross-reactivity of vaccines and whether or not this may be decreasing owing to widespread vaccine use. In this in vitro study, we have compared the ability of antisera to two vaccine viruses (FCV strain F9 and FCV strain 255) to neutralise a panel of 40 recent UK field isolates. These 40 isolates were obtained by randomised, cross-sectional sampling of veterinary practices in different geographical regions of the UK so as to ensure they were representative of viruses circulating in the veterinary-visiting population of cats in the UK. Virus neutralisation assays showed that both vaccine strains are still broadly cross-reactive, with F9 antiserum neutralising 87.5% and 255 antiserum 75% of isolates tested with antiserum dilutions of 1 in 2 or greater. However, when antibody units were used, in order to take account of differences in homologous titres between antisera, fewer isolates were neutralised, with F9 antiserum showing a slightly higher proportion of isolates neutralised than 255. Multivariable analysis of the sample population of 1206 cats from which the 40 isolates were derived found that vaccinated cats were at a decreased risk of being positive for FCV, whereas cats from households with more than one cat, and cats with mouth ulcers were at increased risk. In addition as cats became older their risk of shedding FCV decreased.  相似文献   

3.
An attenuated respiratory disease vaccine against feline viral rhinotracheitis (FVR) and feline calicivirus (FCV) disease was evaluated for safety and efficacy in specific-pathogen-free cats. Twenty cats were vaccinated twice intramuscularly, with 28 days between vaccinations. Ten unvaccinated cats were used as contact controls. Adverse effects were not noticed after vaccination, and the vaccinal virus did not spread to contact controls. Arithmetical mean serum-neutralizing titers against vaccinal FCV strain F9 and challenge FCV strain 255 were 1:13 and 1:15 at 28 days after the 1st inoculation. These titers increased to 1:45 and 1:196 after the 2nd inoculation. After challenge exposure of vaccinated cats to virulent FCV 255 virus, mean titers increased to 1:129 and 1:865, respectively for F9 and 255 viruses. The F9 postchallenge mean titer for vaccinated cats was 21.5 times higher than that for the 8 contact controls that survived challenge exposure. The arithmetical mean serum neutralizing titer for FVR was low (1:2) after the 1st vaccination, but increased to 1:35 after the 2nd vaccination. Challenge exposure to virulent FVR virus resulted in a marked anamnestic immune response (mean titer of 1:207, compared with 1:12 for contact controls). In general, vaccinated cats remained alert and healthy after challenge exposure with FCV-255, whereas unvaccinated contact control cats developed definite signs of FCV disease, including central nervous system (CNS) depression (6 of 10) and dyspnea indicative of pneumonia (5 of 10). Two controls died of severe pneumonia. A mild fibrile response was detected in 28% of vaccinated cats, compared with a more severe febrile response in 78% of control cats. Some vaccinated cats developed minute lingual ulcers that did not appear to be detrimental to the health of the cat. After FVR challenge exposure, vaccinated cats were free of serious clinical signs. Five of 18 vaccinated cats had mild signs of FVR, including an occasional sneeze, low temperature, and mild serous lacrimation for 1 or 2 days. Contact controls developed definite clinical signs of FVR. The combined FVR-FCV vaccine appears to be safe and reasonably efficacious. Vaccination against FCV disease and FVR should be part of the routine feline immunization program.  相似文献   

4.
This study examined a panel of 110 UK field isolates of feline calicivirus (FCV) for susceptibility to cross-neutralisation by a panel of eight antisera raised in cats infected with FCV strains F9, 255, FCVG1 and FCV431. The pairs of antisera raised against F9 or 255, neutralised 20 and 21 per cent or 37 and 56 per cent of field strains of virus respectively. In contrast, the pairs of antisera raised against the newer vaccine strains FCVG1 or FCV431 neutralised 29 and 70 per cent or 67 and 87 per cent of field strains respectively. Antisera raised against the two newer strains, namely FCVG1 and FCV431, neutralised a greater proportion of field strains of calicivirus than antisera raised against the older FCV vaccine strains F9 and 255.  相似文献   

5.
OBJECTIVE: To determine whether detection of virus-specific serum antibodies correlates with resistance to challenge with virulent feline herpesvirus 1 (FHV-1), feline calicivirus (FCV), and feline parvovirus (FPV) in cats and to determine percentages of client-owned cats with serum antibodies to FHV-1, FCV, and FPV. DESIGN: Prospective experimental study. ANIMALS: 72 laboratory-reared cats and 276 client-owned cats. PROCEDURES: Laboratory-reared cats were vaccinated against FHV-1, FCV, and FPV, using 1 of 3 commercial vaccines, or maintained as unvaccinated controls. Between 9 and 36 months after vaccination, cats were challenged with virulent virus. Recombinant-antigen ELISA for detection of FHV-1-, FCV-, and FPV-specific antibodies were developed, and results were compared with results of hemagglutination inhibition (FPV) and virus neutralization (FHV-1 and FCV) assays and with resistance to viral challenge. RESULTS: For vaccinated laboratory-reared cats, predictive values of positive results were 100% for the FPV and FCV ELISA and 90% for the FHV-1 ELISA. Results of the FHV-1, FCV, and FPV ELISA were positive for 195 (70.7%), 255 (92.4%), and 189 (68.5%), respectively, of the 276 client-owned cats. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that for cats that have been vaccinated, detection of FHV-1-, FCV-, and FPV-specific antibodies is predictive of whether cats are susceptible to disease, regardless of vaccine type or vaccination interval. Because most client-owned cats had detectable serum antibodies suggestive of resistance to infection, use of arbitrary booster vaccination intervals is likely to lead to unnecessary vaccination of some cats.  相似文献   

6.
Four types of commercially available feline calicivirus (FCV) vaccine were compared in terms of their efficacy on the basis of the ability of the sera of specific-pathogen-free cats immunized by two injections of each type of vaccine to neutralize FCV field isolates. Each vaccine immune serum neutralized relatively well strains F4, F9, and 255, which were FCV laboratory strains. As to 36 strains of field isolates, however, vaccines A, B, C, and D immune sera did not neutralize 18-20 of the strains (50.0%-55.6%), 19-22 of the strains (52.8%-61.1%), 22-25 of the strains (61.1%-69.4%), and 8-16 of the strains (22.2%-44.4%), respectively. These results indicate that there is much difference in neutralizing antigenicity between the existing vaccine strains and the FCV strains that are prevalent in Japan, suggesting the need for improvement of FCV vaccines.  相似文献   

7.
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8.
Feline caliciviruses (FCVs) are potential etiologic agents in feline idiopathic lower urinary tract disease (I-LUTD). By means of a modified virus isolation method, we examined urine obtained from 28 male and female cats with nonobstructive I-LUTD, 12 male cats with obstructive I-LUTD, and 18 clinically healthy male and female cats. All cats had been routinely vaccinated for FCV. Two FCVs were isolated; I (FCV-U1) from a female cat with nonobstructive I-LUTD, and another (FCV-U2) from a male cat with obstructive I-LUTD. To determine the genetic relationship of FCV-U1 and FCV-U2 to other FCVs. capsid protein gene RNA was reverse transcribed into cDNA, amplified, and sequenced. Multiple amino acid sequence alignments and phylogenetic trees were constructed for the entire capsid protein, hypervariable region E, and the more conserved (nonhypervariable) regions A, B, D, and F. When compared to 23 other FCV isolates with known biotypes, the overall amino acid sequence identity of the capsid protein of FCV-U1 and FCV-U2 ranged from 83 to 96%; identity of hypervariable regions C and E ranged from 58 to 85%. Phylogenetically, FCV-U1 clearly separated from other FCV strains in phenograms based on nonhypervariable regions. In contrast, FCV-U2 consistently segregated with the Urbana strain in all phenograms. Clustering of isolates by geographic origin was most apparent in phenograms based on nonhypervariable regions. No clustering of isolates by biotype was apparent in any phenograms. Our results indicate that FCV-UI and FCV-U2 are genetically distinct from other known vaccine and field strains of FCV.  相似文献   

9.
Feline calicivirus (FCV) is a highly infectious pathogen in cats and widely distributed worldwide with high genetic variation. Full-length open reading frame 2 of 5 from recently isolated Korean FCV isolates were sequenced and compared with those of global isolates. The results of phylogenetic analysis supported dividing global FCV isolates into two genogroups (type I and II) and demonstrated the presence of genogroup II in Korea, indicating their geographic spread in East Asia. High sequence variations in region E of the FCV isolates emphasizes that a novel vaccine needs to be developed to induce protective immunity against various FCV strains.  相似文献   

10.
BackgroundFeline calicivirus (FCV) is a common pathogen of felids, and FCV vaccination is regularly practiced. The genetic variability and antigenic diversity of FCV hinder the effective control and prevention of infection by vaccination. Improved knowledge of the epidemiological characteristics of FCV should assist in the development of more effective vaccines.ObjectivesThis study aims to determine the prevalence of FCV in a population of cats with FCV-suspected clinical signs in Hangzhou and to demonstrate the antigenic and genetic relationships between vaccine status and representative isolated FCV strains.MethodsCats (n = 516) from Hangzhou were investigated between 2018 and 2020. The association between risk factors and FCV infection was assessed. Phylogenetic analyses based on a capsid coding sequence were performed to identify the genetic relationships between strains. In vitro virus neutralization tests were used to assess antibody levels against isolated FCV strains in client-owned cats.ResultsThe FCV-positive rate of the examined cats was 43.0%. Risk factors significantly associated with FCV infection were vaccination status and oral symptoms. Phylogenetic analysis revealed a radial phylogeny with no evidence of temporal or countrywide clusters. There was a significant difference in the distribution of serum antibody titers between vaccinated and unvaccinated cats.ConclusionsThis study revealed a high prevalence and genetic diversity of FCV in Hangzhou. The results indicate that the efficacy of FCV vaccination is unsatisfactory. More comprehensive and refined vaccination protocols are an urgent and unmet need.  相似文献   

11.
Epidemiology of upper respiratory infections of cats was studied. Nasal, ocular, and oral swabs collected from 111 cats presented at animal hospitals during the past 2.5 years were examined. Twenty-four (21.6%) and 4 (3.6%) cats were diagnosed as feline calicivirus (FCV) infection and feline viral rhinotracheitis, respectively, indicating FCV is more prevalent than feline herpesvirus-1, which revealed a considerable shift from data obtained in 1970s. Cat sera immunized by using vaccines containing either FCV F9 or 255 strains neutralized 42.9% and 66.7% of the FCV isolates, respectively. Chlamydia psittaci, examined by a PCR assay amplifying the ompA gene, was found in 26.9% of 26 diseased cats that typically showed conjunctivitis and rhinitis.  相似文献   

12.
In June 1993, two of five pet cats kept in Yokohama city in Japan suddenly became agitated and died. Feline calicivirus (FCV) was isolated from them. One strain (FCV-S) was isolated from the spinal cord, lung and tonsil of cat 1, another (FCV-B) from the ileum, medulla oblongata and cervical spinal cord of cat 2, and a third (FCV-SAKURA) from the oral cavity of one of the three surviving cats which showed no clinical signs. These three strains were equally resistant to pH 3.0 and serologically similar to each other, but distinct from strain F9. A genetic analysis, using a 208 base pair fragment from region E of the capsid, showed that FCV-Ari had a 70.4 per cent nucleotide and 77.3 per cent amino acid homology and FCV-F9 had a 68.6 per cent nucleotide and 73.9 per cent amino acid homology with the three strains, indicating that these two strains were genetically distinct from the three new isolates. Unvaccinated cats and cats which had been vaccinated against FCV-F9 developed watery diarrhoea but did not become agitated after the administration of FCV-S. The FCV-S strain did not induce signs of excitability after it was administered orally to specific pathogen-free cats.  相似文献   

13.
Feline calicivirus (FCV) is characterised by a high degree of antigenic variation potentially compromising vaccine efficacy. Inclusion of several FCV strains or antigens in current vaccines could be a means to improve protection against antigenically distinct isolates. This study evaluated the synergy between two FCV strains (FCVG1 and FCV431) by comparing immunity induced by either strain with that provided by a combination of the two strains against an heterologous challenge with antigenically distant FCV strains (FCV393 and FCV220). Thirty-two SPF kittens were randomly allocated to four groups of eight cats in each group. Groups B, C and D cats were vaccinated once subcutaneously with strains FCVG1, FCV431, and FCVG1 + FCV431, respectively. Each kitten received a total dose of 10(3.4) CCID50 of FCV. Control group A was not immunised. On day 31, four cats from each group were challenged oronasally with FCV220 and four cats with FCV393. Following challenge, the cats were monitored for clinical signs, viral shedding and antibody responses. FCV220 and FCV393 induced severe clinical signs in control cats typical of FCV infection. Immunisation with both strains mixed together induced higher neutralizing antibody titres against FCV220 and FCV393 strains on average. Protection was observed in all groups, however combination of the two strains resulted in a better clinical protection and reduction of virus shedding after heterologous challenge. A moderate correlation was observed between neutralizing antibody titres at the time of challenge and protection against clinical signs. These results indicated that vaccines combining antigens from different FCV strains may induce a broader heterologous protection.  相似文献   

14.
Virus-like particles (VLPs) were produced in insect cells infected with a recombinant baculovirus containing the capsid gene of feline calicivirus strain F9 (FCV-F9). The FCV VLPs were morphologically and antigenically similar to the native virus and contained a single capsid protein with a molecular weight of approximately 60 kDa that reacted with FCV antiserum. Moreover, following immunization of rabbits, VLPs were able to elicit neutralizing antibodies against several FCV strains isolated from clinical samples. Our preliminary results showed that FCV-VLP could be considered a candidate vaccine against FCV infections.  相似文献   

15.
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   

16.
The efficacy of an inactivated vaccine derived from feline calicivirus (FCV) strain FS2 was assessed against challenge with three UK field strains of FCV. The mean clinical score, calculated on the number of signs recorded per day over 21 days after challenge, was lower for vaccinated cats when compared to unvaccinated animals though the difference was not statistically significant. All cats excreted FCV throughout the three weeks following challenge and there was no difference in the number of days of virus shedding during this period between vaccinated and unvaccinated animals. The development of FCV serum neutralising antibody titres following vaccination and challenge was recorded. In the second part of the study the ability of vaccinated and challenged cats to become FCV carriers and then infect susceptible in-contact animals was demonstrated.  相似文献   

17.
旨在了解上海地区猫杯状病毒(feline calicivirus, FCV)VP1基因与致病性,采用常规方法分离鉴定出13株FCV,经RT-PCR和测序获得分离株VP1的基因序列,与参考株VP1基因进行同源性和遗传演化分析,对2株分离株进行动物致病性试验。结果显示,13株上海地区分离株VP1基因核苷酸序列相互间相似性为74.3%～99.8%,与参考株核苷酸序列和氨基酸序列相似性也较低,符合FCV易突变的特征;进化树分析表明,上海地区FCV流行株主要来自国内北方地区,少数毒株来自国外地区;通过对宿主临床症状、VP1进化树和VS-FCV特征性氨基酸位点进行分析,筛选出7株FCV强毒株;动物致病性试结果验表明,FCV-SH202101株和FCV-SH202113株可导致感染猫发病和死亡,潜伏期为1～2 d,接种后第3天即可检测到排毒,不同年龄段猫的病程不一致,可导致幼猫5 d后死亡,成年猫病程可持续11～18 d, 2株分离株在致病性方面均符合VS-FCV特征。本研究丰富了中国FCV的分子流行病学资料,为VS-FCV毒株的筛选提供了有力的证据,也为FCV疫苗的研究提供了技术支持。  相似文献   

18.
The molecular epidemiology of the infectious disease caused by feline calcivirus (FCV) in Japan was investigated by analysing the phylogenetic relationship among 21 Japanese field isolates, including the F4 strain, and 30 global isolates. Parts of the capsid gene (B–F) of the isolates were amplified by RT-PCR, and the amino acid sequences were compared with those from the global isolates. Thirty-seven and 14 out of a total of 51 isolates were clustered into two distinct genogroups, I and II respectively, by UPGMA and NJ analysis. Seven of the 21 Japanese isolates (33%) fell into group I together with 30 global isolates, while the other 14 Japanese isolates (67%) belonged to group II. The bootstrap repetition analysis of groups I and II formed by the NJ method gave a value of 99.0%. The 14 latter Japanese isolates were clearly separated from the isolates in group I, and they were different from any previously known FCV, forming a new genogroup, which implies that this lineage has been confined to Japan. Comparing the amino acid sequences shared by groups I and II, the amino acid at position 377 in B region was asparagine (Asn or Asp (NH2)) in group I, while it was lysine (Lys) in all the strains in group II. Similarly, the amino acid at position 539 in the F region was alanine (Ala) or proline (Pro) in group I, while it was valine (Val) in group II; glycine (Gly) at position 557 in group I was serine (Ser) in Group II; and phenylalanine (Phe) or leucine (Leu) at position 566 in genogroup I was tyrosine (Tyr) in group II.  相似文献   

19.
The capsid protein of Australian feline calicivirus (FCV) isolates is demonstrably different from the prototype strain F9. Five Australian isolates of FCV, dating from 1970 to 1989, were analysed by western blotting and immunoprecipitation. Varying reactivity to a panel of F9 specific monoclonal antibodies (MAbs) was observed. DNA sequencing of RT-PCR generated clones supported the observation of variation between capsid proteins. Predicted amino acid sequences varied by 11 to 17.5% across the whole capsid when compared to the published F9 sequence. Differences in amino acid sequence were most apparent in previously described hypervariable regions (C and E). Within hypervariable region E differences of 22 to 34% were observed compared to F9. The observed lack of reactivity to F9 MAbs correlated with amino acid changes within previously characterized binding sites within region E.  相似文献   

20.
Commercially available vaccines have been used widely to prevent feline calicivirus infection (FCI). However, with their widespread use, field strains, which are weakly cross-reactive with the live-virus vaccine strain F9, have posed the problem of vaccine breakdown. Recently the existence of FCV—associated virulent systemic disease (VSD) has been published. But their molecular diversity, antigenic mutations and physicochemical property have not been sufficiently clarified. Thus, we experimentally gave the vaccine breakdown strain (VBS) H10 to cats that had been inoculated with an F9 live vaccine. After the administration of strain H10, vaccinated cats (1 through 4) had no respiratory symptoms, whereas the non-vaccinated cat 5 showed clinical symptoms such as a fever of over 40°C, loss of vitality, decreased appetite, diarrhea, and nasal discharge after receiving strain H10, and died. Lethal FCV is rare, and may be a virulent systemic disease (VSD)—inducing strain. This is the initial report on VSD in Japan. It has been reported that symptoms of VSD were similar in vaccinated and nonvaccinated cats on experimental infection. However, no VSD-like symptoms developed, and the incidence of the disease varied depending on the presence or absence of vaccination, suggesting that there are two mechanisms of vaccine breakdown: one is associated with the vaccine immunity level, and the other is not. The characteristics of the VBS revealed were: (1) the duration of virus excretion was short when the originally carried antibody titer before virus challenge was high, (2) the excreted viral molecular species varied daily, not being limited to a specific species with time, and (3) the acquired physicochemical properties did not persist, and altered daily. FCV-VBS alters the molecular species and physicochemical properties daily due to the reduction of host immunity, which may lead to VSD.  相似文献   

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