Mengovirus is a prototypical member of the cardiovirus genus of the fa
mily Picornaviridae. The positive-strand RNA genome is 7761 bases in l
ength and encodes a polyprotein of 2293 amino acids. The 5' non-coding
region (758 bases) contains an unusual homopolymeric poly(C) tract, W
hich in the wild-type virus, has a sequence of C50UC10. We have discov
ered through genetic engineering that truncation or deletion of this p
oly(C) sequence yields infectious virus isolates that grow well in cel
l culture, but are 10(6) to 10(9) fold less pathogenic to mice than th
e wild type strain. Animals receiving sublethal doses of the short pol
y(C) strains characteristically develop high levels of neutralizing an
tibodies and acquire lifelong protective immunity against challenge wi
th wild type virus. Effectively, the genetically engineered strains ar
e superb vaccines against cardiovirus disease. Moreover, their potenti
al is not limited to murine hosts. Pigs and sub-human primates have al
so been protectively vaccinated with short poly(C) tract Mengoviruses.
The molecular mechanism of poly(C)-mediated pathogenesis is currently
under study. Most hypotheses link the activity to induction of the an
tiviral cytokine, interferon.