Immunization of macaques with full-length SIV nucleocapsid mutant DNA

The Zn(2+)-finger structures (CCHC) found in retroviral nucleocapsid (NC) proteins are necessary for packaging the retroviral genomic RNA during budding and maturation of the virus particle. Transfection of an SIV mutant lacking 4 amino acids at the beginning of the second zinc finger resulted in expression of non-infectious virus particles containing the full complement of viral proteins and were deficient in genomic RNA. To determine if this proviral DNA could be expressed in vivo, five macaques were inoculated intramuscularly with this nucleocapsid mutant SIV DNA. None of the macaques showed any signs of a productive SIV infection, indicating that the DNA construct was safe. Antibody detected by ELISA after DNA inoculations indicated that the proviral DNA had been expressed. Four control animals received vector plasmid DNA lacking the SIV construct. All animals were challenged with 20 animal infectious doses of SIV(Mne) E11s and results through 16 weeks post challenge have been evaluated. All four controls became infected and initial plasma virus levels ranged between 10(5) to 10(6) genome equivalents/ml. Only one animal of the vaccinated group showed virus levels similar to the controls. The remaining vaccinated animals had either reduced or no detectable plasma virus and additional analysis is in progress. Inoculation of macaques with NC mutant SIV DNA resulted in seroconversion and partial efficacy on challenge.

See More