The invention contemplates a new synthetic, codon-optimized Sin Nombre virus (SNV) full-length M gene open reading frame (ORF) that encodes a unique consensus amino acid sequence. The SNV ORF was cloned into a plasmid to form the first stable recombinant SNV full-length M gene that elicits neutralizing antibodies. The gene can be engineered into a vaccine system, and is useful to protect mammals against infection with Sin Nombre virus.