Two Indian PPRV isolates were subjected to thermal hardening procedures to increase the proportion of temperature-resistant virions. Initial infectivity loss was compensated by titre increases on subsequent cell passages at 37 degrees C. The immunogenicity of 'thermostable' viruses was assessed by virulent PPRV challenge and for safety by host animal inoculation and antibodies assessment. Vaccine viruses were not found using PCR on ocular and nasal swabs, although virus nucleic acid and antigens were demonstrated in spleen and lymph nodes by FAT and PCR. One vaccine strain (MIBI 87(T)) giving 100% protection (tested on only a few animals) was freeze dried and the minimum protective dose calculated. Changes in the virus genome after thermo-adaptation were examined using RT-PCR to amplify portions of the F gene, and three base changes were observed in the thermostable PPR strain (compared with the F gene sequence of the Nigerian PPRV strain). At room temperature, the titre and potency of the thermo-adapted vaccine remained constant up to one month at the 10(5.5) TCID50 level, and was 10(4.5) TCID50/100 mu l after two months. Field trials with over 40 000 doses of the thermostable vaccine under various environmental conditions have given serum neutralization titres exceeding 2(3) and are assumed protective.
CITATION STYLE
Palaniswami, K. S., Thangavelu, A., & Velmurugan, R. (2005). Development of Thermostable Peste Des Petits Ruminants (PPR) Virus Vaccine and Assessment of Molecular Changes in the F Gene. In Applications of Gene-Based Technologies for Improving Animal Production and Health in Developing Countries (pp. 673–678). Springer-Verlag. https://doi.org/10.1007/1-4020-3312-5_52
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