The present invention provides a recombinant attenuated respiratory syncytial virus (RSV) comprising i) a nucleic acid encoding an F protein of a stabilized pre-fusion respiratory syncytial virus (RSV) or its analogue, variant, or fragment; or ii) a nucleic acid encoding a G protein of vesicular stomatitis Indiana virus (VSV) or its analogue, variant, or fragment, and provides a genome of the recombinant RSV, and a recombinant vector comprising the genome. The recombinant attenuated RSV can be provided as a live vaccine strain which is safe and has excellent stability while maintaining infectiousness.

The present disclosure relates to paramyxoviruses, in particular attenuated avian avulaviruses (para, ortho and meta), mutated and genetically modified forms, as well as a vaccine formulation comprising an attenuated avian avulavirus and uses/methods of use thereof.