Dataset Information

Retrospective evaluation of foot-and-mouth disease vaccine effectiveness in Turkey.

ABSTRACT: Foot-and-mouth disease (FMD) is present in much of Turkey and its control is largely based on vaccination. The arrival of the FMD Asia-1 serotype in Turkey in 2011 caused particular concern, spreading rapidly westwards across the country towards the FMD free European Union. With no prior natural immunity, control of spread would rely heavily on vaccination. Unlike human vaccines, field protection is rarely evaluated directly for FMD vaccines. Between September 2011 and July 2012 we performed four retrospective outbreak investigations to assess the vaccine effectiveness (VE) of FMD Asia-1 vaccines in Turkey. Vaccine effectiveness is defined as the reduction in risk in vaccinated compared to unvaccinated individuals with similar virus exposure in the field. The four investigations included 12 villages and 1230 cattle >4 months of age. One investigation assessed the FMD Asia-1 Shamir vaccine, the other three evaluated the recently introduced FMD Asia-1 TUR 11 vaccine made using a field isolate of the FMD Asia-1 Sindh-08 lineage that had recently entered Turkey. After adjustment for confounding, the TUR 11 vaccine provided moderate protection against both clinical disease VE=69% [95% CI: 50%-81%] and infection VE=63% [95% CI: 29%-81%]. However, protection was variable with some herds with high vaccine coverage still experiencing high disease incidence. Some of this variability will be the result of the variation in virus challenge and immunity that occurs under field conditions. In the outbreak investigated there was no evidence that the Asia-1 Shamir vaccine provided adequate protection against clinical FMD with an incidence of 89% in single vaccinated cattle and 69% in those vaccinated two to five times. Based on these effectiveness estimates, vaccination alone is unlikely to produce the high levels of herd immunity needed to control FMD without additional control measures.

SUBMITTER: Knight-Jones TJ

PROVIDER: S-EPMC3991324 | biostudies-other | 2014 Apr

REPOSITORIES: biostudies-other

ACCESS DATA

Publications

Retrospective evaluation of foot-and-mouth disease vaccine effectiveness in Turkey.

Knight-Jones T J D TJ Bulut A N AN Gubbins S S Stärk K D C KD Pfeiffer D U DU Sumption K J KJ Paton D J DJ

Vaccine 20140211 16

Foot-and-mouth disease (FMD) is present in much of Turkey and its control is largely based on vaccination. The arrival of the FMD Asia-1 serotype in Turkey in 2011 caused particular concern, spreading rapidly westwards across the country towards the FMD free European Union. With no prior natural immunity, control of spread would rely heavily on vaccination. Unlike human vaccines, field protection is rarely evaluated directly for FMD vaccines. Between September 2011 and July 2012 we performed fou ...[more]

PMID: 24530150

Similar Datasets

Project description:BackgroundFoot-and-mouth disease (FMD) is the most economically important and highly contagious disease of cloven-hoofed animals worldwide. Control of the disease has been mainly based on large-scale vaccinations with whole-virus inactivated vaccines. In recent years, a series of outbreaks of type O FMD occurred in China (including Chinese Taipei, Chinese Hong Kong) posed a tremendous threat to Chinese animal husbandry. Its causative agent, type O FMDV, has evolved into three topotypes (East-South Asia (ME-SA), Southeast Asia (SEA), Cathay (CHY)) in these regions, which represents an important obstacle to disease control. The available FMD vaccine in China shows generally good protection against ME-SA and SEA topotype viruses infection, but affords insufficient protection against some variants of the CHY topotype. Therefore, the choice of a new vaccine strain is of fundamental importance.ResultsThe present study describes the generation of a full-length infectious cDNA clone of FMDV vaccine strain and a genetically modified virus with some amino acid substitutions in antigenic sites 1, 3, and 4, based on the established infectious clone. The recombinant viruses had similar growth properties to the wild O/HN/CHA/93 virus. All swine immunized with inactivated vaccine prepared from the O/HN/CHA/93 were fully protected from challenge with the viruses of ME-SA and SEA topotypes and partially protected against challenge with the virus of CHY topotype at 28 days post-immunization. In contrast, the swine inoculated with the genetically modified vaccine were completely protected from the infection of viruses of the three topotypes.ConclusionsSome amino acid substitutions in the FMDV vaccine strain genome did not have an effect on the ability of viral replication in vitro. The vaccine prepared from genetically modified FMDV by reverse genetics significantly improved the protective efficacy to the variant of the CHY topotype, compared with the wild O/HN/CHA/93 virus. Thus, the full-length cDNA clone of FMDV can be a useful tool to develop genetically engineered FMDV vaccine candidates to help control porcinophilic FMD epidemics in China.

Project description:Despite years of biannual mass vaccination of cattle, foot-and-mouth disease (FMD) remains uncontrolled in Anatolian Turkey. To evaluate protection after mass vaccination we measured post-vaccination antibodies in a cohort of cattle (serotypes O, A and Asia-1). To obtain results reflecting typical field protection, participants were randomly sampled from across Central and Western Turkey after routine vaccination. Giving two-doses one month apart is recommended when cattle are first vaccinated against FMD. However, due to cost and logistics, this is not routinely performed in Turkey, and elsewhere. Nested within the cohort, we conducted a randomised trial comparing post-vaccination antibodies after a single-dose versus a two-dose primary vaccination course. Four to five months after vaccination, only a third of single-vaccinated cattle had antibody levels above a threshold associated with protection. A third never reached this threshold, even at peak response one month after vaccination. It was not until animals had received three vaccine doses in their lifetime, vaccinating every six months, that most (64% to 86% depending on serotype) maintained antibody levels above this threshold. By this time cattle would be >20 months old with almost half the population below this age. Consequently, many vaccinated animals will be unprotected for much of the year. Compared to a single-dose, a primary vaccination course of two-doses greatly improved the level and duration of immunity. We concluded that the FMD vaccination programme in Anatolian Turkey did not produce the high levels of immunity required. Higher potency vaccines are now used throughout Turkey, with a two-dose primary course in certain areas. Monitoring post-vaccination serology is an important component of evaluation for FMD vaccination programmes. However, consideration must be given to which antigens are present in the test, the vaccine and the field virus. Differences between these antigens affect the relationship between antibody titre and protection.

Project description:There are seven antigenically distinct serotypes of foot-and-mouth disease virus (FMDV), each of which has intratypic variants. In the present study, we have developed methods to efficiently generate promising vaccines against seven serotypes or subtypes. The capsid-encoding gene (P1) of the vaccine strain O1/Manisa/Turkey/69 was replaced with the amplified or synthetic genes from the O, A, Asia1, C, SAT1, SAT2, and SAT3 serotypes. Viruses of the seven serotype were rescued successfully. Each chimeric FMDV with a replacement of P1 showed serotype-specific antigenicity and varied in terms of pathogenesis in pigs and mice. Vaccination of pigs with an experimental trivalent vaccine containing the inactivated recombinants based on the main serotypes O, A, and Asia1 effectively protected them from virus challenge. This technology could be a potential strategy for a customized vaccine with challenge tools to protect against epizootic disease caused by specific serotypes or subtypes of FMDV.IMPORTANCE Foot-and-mouth disease (FMD) virus (FMDV) causes significant economic losses. For vaccine preparation, the selection of vaccine strains was complicated by high antigenic variation. In the present study, we suggested an effective strategy to rapidly prepare and evaluate mass-produced customized vaccines against epidemic strains. The P1 gene encoding the structural proteins of the well-known vaccine virus was replaced by the synthetic or amplified genes of viruses of seven representative serotypes. These chimeric viruses generally replicated readily in cell culture and had a particle size similar to that of the original vaccine strain. Their antigenicity mirrored that of the original serotype from which their P1 gene was derived. Animal infection experiments revealed that the recombinants varied in terms of pathogenicity. This strategy will be a useful tool for rapidly generating customized FMD vaccines or challenge viruses for all serotypes, especially for FMD-free countries, which have prohibited the import of FMDVs.

Dataset Information

Retrospective evaluation of foot-and-mouth disease vaccine effectiveness in Turkey.

Publications

Retrospective evaluation of foot-and-mouth disease vaccine effectiveness in Turkey.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets