Dominance of a nonpathogenic glycoprotein gene over a pathogenic glycoprotein gene in rabies virus.
The nonpathogenic phenotype of the live rabies virus (RV) vaccine SPBNGAN is determined by an Arg-->Glu exchange at position 333 in the glycoprotein, designated GAN. We recently showed that after several passages of SPBNGAN in mice, an Asn-->Lys mutation arose at position 194 of GAN, resulting in GAK, which was associated with a reversion to the pathogenic phenotype. Because an RV vaccine candidate containing two GAN genes (SPBNGAN-GAN) exhibits increased immunogenicity in vivo compared to the single-GAN construct, we tested whether the presence of two GAN genes might also enhance the probability of reversion to pathogenicity. Comparison of SPBNGAN-GAN with RVs constructed to contain either both GAN and GAK genes (SPBNGAN-GAK and SPBNGAK-GAN) or two GAK genes (SPBNGAK-GAK) showed that while SPBNGAK-GAK was pathogenic, SPBNGAN-GAN and SPBNGAN-GAK were completely nonpathogenic and SPBNGAK-GAN showed strongly reduced pathogenicity. Analysis of genomic RV RNA in mouse brain tissue revealed significantly lower virus loads in SPBNGAN-GAK- and SPBNGAK-GAN-infected brains than those detected in SPBNGAK-GAK-infected brains, indicating the dominance of the nonpathogenic phenotype determined by GAN over the GAK-associated pathogenic phenotype. Virus production and viral RNA synthesis were markedly higher in SPBNGAN-, SPBNGAK-GAN-, and SPBNGAN-GAK-infected neuroblastoma cells than in the SPBNGAK- and SPBNGAK-GAK-infected counterparts, suggesting control of GAN dominance at the level of viral RNA synthesis. These data point to the lower risk of reversion to pathogenicity of a recombinant RV carrying two identical GAN genes compared to that of an RV carrying only a single GAN gene.
Faber
Milosz
M
Department of Microbiology and Immunology, Thomas Jefferson University, Philadelphia, PA 19107, USA.
Faber
Marie-Luise
ML
Li
Jianwei
J
Preuss
Mirjam A R
MA
Schnell
Matthias J
MJ
Dietzschold
Bernhard
B
D019943:Amino Acid Substitution; D000818:Animals; D001921:Brain / Q000378:metabolism / Q000821:virology; D002460:Cell Line; D005799:Genes, Dominant; D005814:Genes, Viral; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism*; D008297:Male; D051379:Mice; D020125:Mutation, Missense; D012367:RNA, Viral / Q000096:biosynthesis / Q000235:genetics; D011818:Rabies / Q000235:genetics / Q000378:metabolism*; D011819:Rabies Vaccines / Q000235:genetics / Q000378:metabolism*; D011820:Rabies virus / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D019562:Viral Load; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*
D006023:Glycoproteins; D012367:RNA, Viral; D011819:Rabies Vaccines; D014764:Viral Proteins