The need to apply vaccines in different species – small ruminants
2012 • 1 10 Foot and mouth disease (FMD) has been successfully controlled and eliminated in many parts of the world using conventional disease control measures, including vaccination of domestic animals. Potent vaccines have also been the mainstay in controlling outbreaks in non-enzootic regions. Several characteristics of FMD complicate the use of vaccines to control the disease. Not only are there seven serotypes, with little cross-protection between the serotypes, but genetic and antigenic variants occur within these serotypes. In addition, FMD virus can infect over 70 cloven-hoofed species, many of which are free-living wild animals. The role of sheep and goats in the epidemiology of the disease is poorly understood and perceived differently in different parts of the world. This perception is reflected in the vaccination policies applied in these countries. Cattle are generally the species of choice in vaccination programmes, while sheep and goats are vaccinated in only a small number of countries, and then mostly either for strategic purposes or as part of a routine disease control programme. The general assumption is that sheep and goats do not play a significant role in the spread of the disease or as sentinel animals to detect clinical disease. However, this assumption does not hold true for all circumstances or under all epidemiological conditions. This paper describes the potential circumstances under which the vaccination of small livestock should be considered to mitigate the risk of viral spread or to contain an outbreak of the disease. The need to apply vaccines in different species – small ruminants
Immune responses of goats against foot-and-mouth disease quadrivalent vaccine: comparison of double oil emulsion and aluminium hydroxide gel vaccines in eliciting immunity.
The epidemiological role of small ruminants in foot-and-mouth disease (FMD) outbreaks has been generally neglected. Although, the disease in these species is sub-clinical in nature, their role as virus carriers represents a reservoir for further infection and spread of disease. Data on the usefulness of polyvalent FMD vaccine (FMDV) in goats is scant. Thus, the present study was undertaken to evaluate the benefits of a highly potent polyvalent FMDV in goats. In the present investigations, FMDV quadrivalent double oil emulsion (Montanide ISA 206) vaccines were tested in goats at reduced doses of 2 ml per animal (antigen payload 3.5 microg per serotype per dose). The oil adjuvant elicited superior immune response at any given period than aluminium hydroxide gel (AGS) vaccine and the rapidity of development of response was quicker. The duration of immunity also appeared to be maintained for long period. The differences in immune response between two adjuvant groups were statistically significant (P<0.05). The differences were apparent even in kinetics of immune response. Unlike cattle, goats were found to be late responders for oil-adjuvanted vaccine. Our results indicate possible universal usage of double oil emulsion vaccines for disease control programs irrespective of species of animals.
Foot-and-mouth disease virus crosses the placenta and causes death in fetal lambs.
Eighteen pregnant sheep, six at 45 days gestation and twelve at 75 days gestation, were infected with foot-and-mouth disease virus (FMDV) type O UKG 34/2001. Two sheep from each gestational group were killed at 2, 4, and 7 days post-inoculation (dpi). Three sheep, pregnant for 75 days at infection, were killed at 17 and 18 dpi. Real-time reverse-transcriptase polymerase chain reaction (RT-PCR) and virus isolation (VI) were used to detect viral RNA and infectious virus, respectively, in fetal tissues taken post mortem. Eleven fetuses were obtained from the six sheep inoculated at day 45 of gestation. Of these, two of three fetuses at 2 dpi had viral RNA detected by RT-PCR and virus was detected in one by VI. Viral RNA was detected in two of four fetuses at 4 dpi, while viral RNA and virus were detected in all four fetuses at 7 dpi. No gross abnormalities were evident in these fetuses. In the group inoculated at day 75 of gestation, viral RNA was detected in three of four fetuses at 4 dpi. Virus and viral RNA were detected in three of four fetuses at 7 dpi. Of the seven fetuses examined at 17 and 18 dpi, viral RNA was detected in five, and four of these had died in utero. Gross abnormalities including haemorrhage and oedema in a number of tissues were evident in many of the fetuses in this group, but no vesicular lesions were found. Viral RNA and virus were detected in the amniotic fluid associated with infected fetuses. This study is the first to demonstrate that FMDV may cause transplacental infection and fetal death.