Novel carbon quantum dots can serve as an excellent adjuvant for the gp85 protein vaccine against avian leukosis virus subgroup J in chickens.

To evaluate whether carbon quantum dots (CQDs) can serve as an excellent adjuvant for the gp85 protein vaccine, this study produced recombinant gp85 protein against the avian leukosis virus subgroup J (ALV-J) in chickens. Functionalized CQDs were prepared and then linked to the recombinant gp85 protein. A total of 36 chickens were divided into 3 groups, namely, 2 experimental groups and 1 control group. Chickens from the experimental groups were inoculated twice intramuscularly with purified recombinant gp85 protein with CQDs as adjuvant or Freund's adjuvant emulsion at 14 and 21 D, whereas those from the control group were inoculated with an equivalent volume of PBS. At 35 D, the chickens were challenged with a 102.4 50% tissue culture infective dose of ALV-J. Blood samples were collected from each chicken at weekly intervals for serum antibody and viremia analyses. Results indicated that immunization with gp85-CQDs or gp85-Freund's adjuvant induced the inoculated chickens to produce positive serum antibodies (sample-to-positive ratio >0.6) at the 3rd week and persisted over 9 wk. Antibody levels in the gp85-CQDs group were higher than those in the gp85–Freund's adjuvant group. Differences were significant at 21 D (P < 0.05) and extremely significant from 28 D to 70 D (P < 0.01). Additionally, results of viremia showed higher protection in the gp85-CQDs group than in the Freund's adjuvant group. These findings highlighted the potential of CQDs as excellent candidate nanovehicles for vaccine delivery.