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1.
Humoral and mucosal (secretory antibody)immune response to FMDV type Asia 1 in cattle was analyzed after vaccination and infection using virus neutralizing test (VNT). Vaccination (1/16th the usual dose) failed to protect cattle from generalized clinical disease following experimental FMDV Asia 1 infection. Our results showed that infection induced higher and prolonged serum antibody titres indicating antigen mass is important for optimal immune response. Experimental FMDV infection induced significant secretory antibody (mucosal) response in cattle. Though, there was no difference in the serum antibody response between the cattle that developed generalized infection (unprotected) and those with only localized infection (protected), secretory antibody response differed, wherein the unprotected cattle had higher secretory response than protected cattle. Thus, FMDV Asia 1 infection stimulates a similar serum antibody response and a unique secretory antibody response among the infected cattle. An erratum to this article can be found at  相似文献   

2.
Foot-and-mouth disease (FMD) is a highly contagious viral infection of significant financial importance to the export and trade of agricultural products. The occurrence of persistently infected "carriers" of FMD-virus (FMDV) in ruminant species adds further complications to disease control. There have been significant discrepancies in reports regarding the pathogenesis of FMDV infection in cattle with specific emphasis on the anatomical sites involved in early and persistent virus replication. In this study, collection of small biopsy samples from the dorsal soft palate (DSP) of live animals was used to investigate the level of FMDV RNA present at this site at sequential time points during the infection. Results were compared to measurements of virus excretion in samples of oropharyngeal fluid collected at corresponding time points. Possible sites of virus persistence were investigated through measurements of the levels of FMDV RNA in the DSP as well as mandibular and retropharyngeal lymph nodes beyond 28 days after infection. Results indicated only low levels of FMDV RNA present in samples of pharyngeal epithelia during both early and persistent phases of infection with significantly higher levels of virus detected in pharyngeal excretions. It is concluded that the targeted area for sampling within the DSP does not harbour significant levels of virus replication during acute or persistent FMDV infection in cattle. Furthermore, the DSP and the mandibular and retropharyngeal lymph nodes cannot be concluded to be principal sites for persistence of FMDV.  相似文献   

3.
The mucosal immune response to foot-and-mouth disease virus (FMDV) type Asia 1 was examined in experimentally infected cattle by assaying antibodies by the virus-neutralizing test (VNT) and IgA ELISA in two secretory fluids, oesophageal pharyngeal fluid (OPF) and oro-nasal fluid (ONF). Out of 17 animals infected by the intradermo-lingual route, 12 became persistently infected (carriers), as defined by positive antigen capture RT-PCR reactions for FMDV RNA in OPF samples collected at 28 days or later after exposure. This proportion of carriers (71%) with FMDV Asia 1 is comparable to other serotypes of the virus. When the two groups were examined, the carriers and non-carriers showed no difference in the serum antibody titre until the end of the experiment at 182 days post-infection (DPI). However, despite an initial similarity significantly higher neutralizing antibody titres and FMDV-specific IgA response were detected among the carriers than the non-carriers in both of the secretory fluids. The response was higher and more stable in ONF compared to OPF. Thus, mucosal antibody assays have the potential to be used as a means of differentiating carrier from non-carrier cattle. Furthermore, the findings are consistent with the higher mucosal antibody response in carriers being an effect of persistent infection rather than the cause.  相似文献   

4.
Foot-and-mouth disease virus (FMDV) causes a highly contagious infection in cloven-hoofed animals. The format of FMD virus-like particles (VLP) as a non-replicating particulate vaccine candidate is a promising alternative to conventional inactivated FMDV vaccines. In this study, we explored a prokaryotic system to express and assemble the FMD VLP and validated the potential of VLP as an FMDV vaccine candidate. VLP composed entirely of FMDV (Asia1/Jiangsu/China/2005) capsid proteins (VP0, VP1 and VP3) were simultaneously produced as SUMO fusion proteins by an improved SUMO fusion protein system in E. coli. Proteolytic removal of the SUMO moiety from the fusion proteins resulted in the assembly of VLP with size and shape resembling the authentic FMDV. Immunization of guinea pigs, swine and cattle with FMD VLP by intramuscular inoculation stimulated the FMDV-specific antibody response, neutralizing antibody response, T-cell proliferation response and secretion of cytokine IFN-γ. In addition, immunization with one dose of the VLP resulted in complete protection of these animals from homologous FMDV challenge. The 50% protection dose (PD50) of FMD VLP in cattle is up to 6.34. These results suggest that FMD VLP expressed in E. coli are an effective vaccine in guinea pigs, swine and cattle and support further development of these VLP as a vaccine candidate for protection against FMDV.  相似文献   

5.
Foot-and-mouth disease (FMD) is one of the most contagious diseases affecting wide range of host species with variable severity and decreased productivity. The present study was undertaken to compare the clinical and leucocytic changes in indigenous Indian cattle and buffaloes experimentally infected with FMD virus (FMDV) Asia 1. A mild type of disease was observed in the cattle, more so in buffaloes infected with FMDV. Difference in terms of type, site and healing of lesion was observed between cattle and buffaloes. Foot lesions were more common than tongue in buffaloes, which were mainly evident in bulb of the heel in contrast to interdigital foot lesions in cattle. Further, FMDV infection induced a transient moderate leucopenia with lymphopenia in both cattle and buffaloes, but monocyte levels diverged. Relationship between the raised body temperature, leucocytic changes and lesion development was observed. Microscopic changes were observed in the keratinized epithelium of tongue and foot. The findings of the present study indicated the need to investigate the early leucocytic changes in cattle and buffaloes in depth for better understanding of the disease process.  相似文献   

6.
The aim of this study was to evaluate the value of commercially available kits for the detection of foot-and-mouth disease (FMD) virus infection in vaccinated cattle. The cattle were vaccinated with a commercial aqueous FMD vaccine type A24 and subsequently challenged 28 days post vaccination with homologous FMD virus. Seven of eight animals were protected from clinical disease and all became carriers. They were bled sequentially for up to 130 days post infection and samples of sera were tested with three ELISA kits: CHEKIT FMD-3ABC, Ceditest FMDV-NS and SVANOIR FMDV 3ABC-Ab ELISA. The Ceditest kit appears to be relatively higher sensitive than the others. When examined with this ELISA, all cattle developed of FMDV nonstructural proteins (NSPs) antibodies and remained positive throughout the period of the experiment. The response of antibodies against 3ABC antigen delayed in two cattle challenged with FMDV A24 virus. One of the cattle reacted negatively in Svanoir ELISA kit and sera from two animals were found negative in CHEKIT ELISA. It can be concluded that all tested kits can be a promising tool for FMD control and eradication campaigns in situation where emergency vaccination was applied.  相似文献   

7.
A novel direct contact transmission model for the study of foot-and-mouth disease virus (FMDV) infection of swine was utilized to investigate transmission characteristics of three FMDV strains belonging to serotypes A, O and Asia1. Each strain demonstrated distinct transmission characteristics and required different exposure times to achieve successful contact transmission. While a 4h exposure was sufficient for strain A24 Cruzeiro (A24Cru), both O1 Manisa and Asia1 Shamir transmission required 18h or more. Viral excretion levels from donors (for all three strains) and virus present in room air (for A24Cru and O1 Manisa) were evaluated and associated with clinical signs and observed transmission pattern. Although all directly inoculated donor animals showed acute FMD, A24Cru had the highest levels of viral shedding in saliva and nasal swabs followed by O1 Manisa and Asia1 Shamir. Virus levels in room air were higher and were detected longer for A24Cru than for O1 Manisa. These results provide direct evidence for important strain-specific variation in transmission characteristics and emphasize the need for thorough evaluation of different FMDV viral strains using a well defined contact transmission methodology. This information is critical for vaccine and biotherapeutic efficacy testing, pathogenesis and disease modeling of FMDV transmission.  相似文献   

8.
FMDV infection can cause a long lasting virus carrier state in the oesophageal-pharyngeal (OP) region of cattle, sheep, goats, African buffalo, wildebeest and kudu. Virus can be recovered from OP fluids with low titres for several months up to more than 2 years. During this time phases of positive virus recovery are interrupted by negative phases. The number of virus carriers decreases as time progresses. The virus carrier state is always accompanied by FMDV antibodies in serum and OP fluid. Vaccinated animals also become virus carriers after FMDV infection, to the same extent as unvaccinated animals. No virus carrier state has been proven in pigs, but it cannot be excluded in some species of deer. Epizootic importance of carrier animals (in FMD) has not been found. Experimental contact transmissions of carrier virus to cattle, sheep and goats have failed. Only buffalo transmit carrier virus to the own species and perhaps to cattle. Nevertheless, virus carriers represent a natural reservoir of FMDV in infected areas and a potential source of antigenically altered virus variants, since continuous variations of the virus and selection of virus mutants take place in the animal during the carrier state.  相似文献   

9.
ABSTRACT: A series of challenge experiments were performed in order to investigate the acute phase responses to foot-and-mouth disease virus (FMDV) infection in cattle and possible implications for the development of persistently infected "carriers". The host response to infection was investigated through measurements of the concentrations of the acute phase proteins (APPs) serum amyloid A (SAA) and haptoglobin (HP), as well as the bioactivity of type 1 interferon (IFN) in serum of infected animals. Results were based on measurements from a total of 36 infected animals of which 24 were kept for observational periods exceeding 28 days in order to determine the carrier-status of individual animals. The systemic host response to FMDV in infected animals was evaluated in comparison to similar measurements in sera from 6 mock-inoculated control animals.There was a significant increase in serum concentrations of both APPs and type 1 IFN in infected animals coinciding with the onset of viremia and clinical disease. The measured parameters declined to baseline levels within 21 days after inoculation, indicating that there was no systemically measurable inflammatory reaction related to the carrier state of FMD. There was a statistically significant difference in the HP response between carriers and non-carriers with a lower response in the animals that subsequently developed into FMDV carriers. It was concluded that the induction of SAA, HP and type 1 IFN in serum can be used as markers of acute infection by FMDV in cattle.  相似文献   

10.
ABSTRACT: Infection of cattle with foot-and-mouth disease virus (FMDV) results in the development of long-term protective antibody responses. In contrast, inactivated antigen vaccines fail to induce long-term protective immunity. Differences between susceptible species have also been observed during infection with FMDV, with cattle often developing persistent infections whilst pigs develop more severe symptoms and excrete higher levels of virus. This study examined the early immune response to FMDV in na?ve cattle after in-contact challenge. Cattle exposed to FMDV were found to be viraemic and produced neutralising antibody, consistent with previous reports. In contrast to previous studies in pigs these cattle did not develop leucopenia, and the proliferative responses of peripheral blood mononuclear cells to either mitogen or third party antigen were not suppressed. Low levels of type 1 interferon and IL-10 were detected in the circulation. Taken together, these results suggest that there was no generalised immunosuppression during the acute phase of FMDV infection in cattle.  相似文献   

11.
Lu Z  Cao Y  Guo J  Qi S  Li D  Zhang Q  Ma J  Chang H  Liu Z  Liu X  Xie Q 《Veterinary microbiology》2007,125(1-2):157-169
Non-structural protein (NSP) 3ABC antibody is considered to be the most reliable indicator of present or past infection with foot-and-mouth disease virus (FMDV) in vaccinated animals. An indirect ELISA was established, using purified His-tagged 3ABC fusion protein as antigen, for detection of the antibody response to FMDV NSP 3ABC in different animal species. The method was validated by simultaneous detection of the early antibody responses to NSP and structural protein (SP) in FMDV Asia 1 infected animals. The performance of the method was also validated by detection of antibody in reference sera from the FMD World Reference Laboratory (WRL) in Pirbright, UK, and comparison with two commercial NSP ELISA kits. The results showed that the antibody response to SP developed more quickly than that to NSP 3ABC in FMDV infected animals. In contact-infected cattle, the antibody response to NSP 3ABC was significantly delayed compared with that to SP antibody. The early antibody responses to SP and NSP 3ABC in FMDV inoculated cattle and contact-infected or inoculated sheep and pigs were generally consistent. In pigs, 3ABC antibody was linked to the presence of clinical signs; however, in sheep, subclinical infection was detected by the development of 3ABC antibodies. Therefore, the antibody responses to 3ABC varied between host species. Eight out of 10 positive serum samples from FMD WRL were tested to be positive at cutoff value of 0.2. The rate of agreement with the ceditest FMDV-NS and the UBI NSP ELISA were 98.05% (302/308) and 93.2% (287/308), respectively. The prevalence of 3ABC antibodies reached 71.4% in some diseased cattle herds. The further work is required to evaluation the performance of this method in different animal species and different field situations.  相似文献   

12.
A single dose of foot-and-mouth disease (FMD) virus protein 1 (VP1) peptide, expressed in Escherichia coli as a fusion protein with 190 amino acids (AA) of the LE' protein of the tryptophan operon of E coli, elicited an immune response in steers sufficient to withstand the challenge of exposure to animals with acute FMD. The 58-micrograms dose of viral peptide, composed of a segment of the VP1 from the A12 strain (A12) of FMD virus (FMDV; A12-32dimer) in a tandem repeat configuration of AA137 through 168 and emulsified with oil adjuvant, elicited a serologic response in cattle equivalent to that obtained using conventional whole virus vaccines. Two groups of swine were vaccinated, 1 with the A12-32dimer as used in cattle and 1 with AA131 through 157 from VP1 of the A24 strain (A24) of FMDV (A24-peptide), expressed in the same system as A12-32dimer, but as a single copy per molecule. In swine, the 58-micrograms dose of the A12-32dimer repeated at 28 days was an effective immunogen; all swine were protected against A12 and, in addition, the vaccine protected 50% of the swine against A24. The 29-micrograms dose of A24-peptide, administered according to the same schedule, elicited protection against A24 in 50% of the vaccinates and, in addition, protected 25% of those vaccinates against A12. The serologic response elicited by A12-32dimer against A24 virus was considerably greater than the response elicited by A24-peptide against A12 virus. The evidence of multiple immunogenic epitopes between AA131 and AA168 was evaluated.  相似文献   

13.
To investigate and optimise detection of carriers, we vaccinated 15 calves with an inactivated vaccine based on foot-and-mouth disease virus (FMDV) A Turkey strain and challenged them and two further non-vaccinated calves with the homologous virus four weeks later. To determine transmission to a sensitive animal, we put a sentinel calf among the infected cattle from 60 days post-infection until the end of the experiment at 609 days post-infection. Samples were tested for the presence of FMDV, viral genome, specific IgA antibodies, antibodies against FMDV non-structural (NS) proteins or neutralising antibodies. Virus and viral genome was intermittently isolated from probang samples and the number of isolations decreased over time. During the first 100 days significantly more samples were positive by RT-PCR than by virus isolation (VI), whereas, late after infection more samples were positive by virus isolation. All the inoculated cattle developed high titres of neutralising antibodies that remained high during the entire experiment. An IgA antibody response was intermittently detected in the oropharyngeal fluid of 14 of the 17 calves, while all of them developed detectable levels of antibodies to NS proteins of FMDV in serum, which declined slowly beyond 34 days post-infection. Nevertheless, at 609 days after inoculation, 10 cattle (60%) were still positive by NS ELISA. Of the 17 cattle in our experiment, 16 became carriers. Despite frequent reallocation between a different pair of infected cattle no transmission to the sentinel calf occurred. It remained negative in all assays during the entire experiment. The results of this experiment show that the NS ELISA is currently the most sensitive method to detect carriers in a vaccinated cattle population.  相似文献   

14.
There are severe international trade restrictions on foot-and-mouth disease (FMD) affected areas. Because of endemic nature of FMD, India started FMD control programme (FMD-CP) using mass vaccination in selected states including Haryana (year 2003). Although no significant incidence of the disease was reported after launching FMD-CP in the state but in order to participate in international trade of animal and animal products, veterinary authorities have to prove that there is no FMD virus (FMDV) circulation in the animal population, for which it is necessary to differentiate the FMD infected and vaccinated animals. For this purpose, an in-house indirect ELISA utilizing baculovirus-expressed FMDV non-structural protein (NSP) 3A was used to find evidence for virus circulation (prevalence of anti-NSP 3A-specific antibodies) by examining serum samples that were collected either before start of FMD-CP or after completion of third phase (Pre-4th) of vaccination in Haryana (India). A significant reduction (P < 0.01) in prevalence of anti-NSP 3A-specific antibodies (possibly carriers) was observed 2 years after launching FMD-CP in Haryana. However, in cattle the percentage of animals with anti-NSP 3A-specific antibodies was found to be significantly higher (P < 0.01) than buffalo, both before (P < 0.01) and after (P < 0.01) launching FMD-CP in the state. The findings of this study suggest that use of FMDV vaccine in cattle and buffaloes in endemic areas reduces virus circulation (carriers) in the vaccinated herds and that the current 3ANSP-ELISA can be successfully used to monitor the FMDV circulation in endemic areas.  相似文献   

15.
Foot-and-mouth disease (FMD) in South American camelids, in dromedaries and Bactrians is reviewed. Recent well-executed experimental studies in New World camels indicate that, although the llama and alpaca can be infected with FMD virus (FMDV) by direct contact, they are not very susceptible and do not pose a risk in transmitting FMD to susceptible animal species. They do not become FMDV carriers. Reports on FMD in dromedaries are, however, conflicting. Serological investigations in Africa and the United Arab Emirates (UAE) on thousands of camel sera were negative and experimental infections have been conducted on only a few dromedaries with one serotype and in one country. The design and execution of most of these experiments were poor and therefore the conclusions are questionable. From these investigations, it seems that dromedaries can contract the disease after experimental infection and through close contact with FMD diseased livestock, but do not present a risk in transmitting FMD to susceptible animals. They do not become FMDV carriers. Recent reports from Mongolia describe similar FMD lesions in Bactrian camels. However, so far no samples have tested positive for FMD. To clarify the situation in Bactrians, samples from suspected clinical cases should be tested because other viral vesicular diseases cannot be distinguished from FMD. Thus, further research on the epidemiology of FMD in camelids is necessary. This would include large-scale serological investigations and experimental infections with different FMD serotypes in connection with susceptible contact animals. The Office International des Epizooties (OIE) Code chapter on FMD includes camelids as being susceptible species to FMD, giving the impression that they are similar to cattle, sheep, goats and pigs in their potential involvement in the epidemiology of FMD. This is clearly not the case, and this issue should be re-addressed by the relevant authorities.  相似文献   

16.
根据GenBank中O型和Asia1型口蹄疫病毒(Foot-and-mouth disease virus,FMDV)的vp3、vp1和2A基因序列,并与其它血清型FMDV的对应基因序列进行比较,设计用于扩增O型和Asia1型FMDV vp1基因的特异性引物,建立O型和Asia1型FMDV RT-PCR鉴别诊断方法。本方法首先用通用型引物进行RT-PCR,确定是否为FMDV感染,然后用特异性引物鉴别O型或Asia1型FMDV的感染。用vp1基因序列分析进行符合性试验,验证了该方法所具有的特异性和敏感性。本方法可用于O型和Asia1型FMD的快速诊断及流行病学调查。  相似文献   

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18.
以豚鼠为试验动物模型,探索一种应用豚鼠替代牛进行牛口蹄疫Asia-1型灭活疫苗效力检验的方法.豚鼠和牛同步对6批牛口蹄疫Asia-1型灭活疫苗进行PD50效力检验,其中2批进行重复性试验.豚鼠分别在免疫后7、14、21和28天采血检测Asia-1型的中和抗体水平.统计学分析显示,测定的豚鼠PD50和牛PD50之间具有极...  相似文献   

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