Evaluation of the Flinders Technology Associates Cards for Storage and Temperature Challenges in Field Conditions for Foot-and-Mouth Disease Virus Surveillance.

Foot-and-mouth disease virus (FMDV) samples transported to the laboratory from far and inaccessible areas for diagnosis and identification of FMDV pose a major problem in a tropical country like India, where wide fluctuation of temperature over a large geographical area is common. Inadequate storage methods lead to spoilage of FMDV samples collected from clinically positive animals in the field. Such samples are declared as non-typeable by the typing laboratories with the consequent loss of valuable epidemiological data. In this study, an attempt was made to evaluate the robustness of Flinders Technology Associates (FTA) cards for storage and transportation of FMDV samples in different climatic conditions which will be useful for FMDV surveillance. Simulation transport studies were conducted using FTA impregnated FMDV samples during post-monsoon (September-October 2010) and summer season (May-June 2012). FMDV genome or serotype could be identified from the FTA cards after the simulation transport studies with varying temperature (22-45°C) and relative humidity (20-100%). The stability of the viral RNA, the absence of infectivity and ease of processing the sample for molecular methods make the FTA cards an useful option for transport of FMDV genome for identification and type determination. The method can be used routinely for FMDV research as it is economical and the cards can be transported easily in envelopes by regular courier/postal systems. The absence of live virus in FTA card can be viewed as an advantage as it restricts the risk of transmission of live virus.

Clinical protection, sub-clinical infection and persistence following vaccination with extinction payloads of O1 Manisa Foot-and-Mouth Disease monovalent vaccine and challenge in goats and comparison with sheep.

Small ruminants play an important role in the epidemiology of Foot-and-Mouth Disease (FMD). Small ruminants are vaccinated with one-half or one-third of cattle dose of oil-based or aqueous vaccines respectively. The extinction antigen payload in vaccine for protection in small ruminants is poorly studied. FMD seronegative Nellore sheep (n=30) and Osmanabadi goats (n=30) were vaccinated with different payloads of O(1) Manisa vaccine (0.45-5 µg). Vaccinated and sero-negative unvaccinated sheep (n=6) and goats (n=6) were challenged intradermally into the coronary band with O(1) Manisa virus. The sheep and goats were monitored for signs of FMD and samples were collected for measuring viraemia and virus associated with nasal swabs and probang samples. Clotted blood was collected for serology. Vaccines containing antigen payload up to 0.94 µg protected sheep and goats against challenge. Sheep and goats vaccinated with 0.45 µg antigen payload were poorly protected against challenge. An antigen payload of 0.94 µg was sufficient to offer complete protection and also absence of carrier status. Sheep and goats with no vaccination or with poor sero conversion to vaccination showed sub-clinical infection and became carriers. The results of the study suggest that vaccination offers protection from clinical disease even at a low payload of 0.94 µg and hence one-half of cattle dose of the oil-based vaccine formulations is sufficient to induce protective immune response in sheep and goats. Since no live virus could be isolated after 5 days post challenge from the nasal swab or probang samples even though viral RNA was detected, the risk of these animals transmitting disease was probably very low.