Described herein are RSV polynucleotide sequences that make use of multiple codons that are containing silent nucleotide substitutions engineered in multiple locations in the genome, wherein the substitutions introduce a numerous synonymous codons into the genome. Due to the large number of defects involved, the attenuated viruses disclosed herein provide a means of producing attenuated, live vaccines against RSV.

Reported herein are presumptively de-attenuating mutations that are useful, either individually or in combinations that may include other known mutations, in producing recombinant strains of human respiratory syncytial virus (RSV) exhibiting attenuation phenotypes. Also described herein is a novel RSV construct, Min_L-NPM2-1(N88K) L, which exhibits an attenuated phenotype, is stable and is as immunogenic as wild type RSV. The recombinant RSV strains described here are suitable for use as live-attenuated RSV vaccines. Exemplary vaccine candidates are described. Also provided are polynucleotide sequences capable of encoding the described viruses, as well as methods for producing and using the viruses.

Embodiments of a recombinant human Parainfluenza Virus (hPIV) F ectodomain trimer stabilized in a prefusion conformation are provided. Also disclosed are nucleic acids encoding the hPIV F ectodomain trimer and methods of producing the hPIV F ectodomain trimer. Methods for inducing an immune response in a subject are also disclosed. In some embodiments, the method can be a method for treating or inhibiting a hPIV infection in a subject by administering a effective amount of the recombinant hPIV F ectodomain trimer to the subject.

A messenger ribonucleic acid (mRNA) vaccine for Bandavirus dabieense (DBV) and a preparation method thereof are provided. The provided mRNA molecule is an mRNA obtained by cloning an optimized DBV glycoprotein gonadotropins (Gn) sequence into a pGEM-3Zf (+) mRNA vaccine vector, linearizing a plasmid via enzyme digestion, and capping and adding a poly(A) tail through an in vitro transcription enzyme method. The mRNA is encapsulated using a lipid nanoparticle delivery system to obtain the mRNA vaccine.

In one aspect, the disclosure relates to recombinant bacterial vectors including a gene encoding at least one antigen from Aeromonas hydrophila or tilapia lake virus, methods of making the same, vaccines incorporating the same, and methods of inducing an immune response in the subject and/or preventing infection by a pathogen in the subject using the same. In one aspect, the subject is a fish in an aquaculture system. In an aspect, the vector or vaccine can be administered by bath immersion or intracoelomic injection and, in some cases, can confer protection against an additional pathogen such as, for example, Edwardsiella piscicida. In any of these aspects, the vectors are susceptible to antibiotics and do not persist in the environment.