Epidemic and maintenance of rabies in Chinese ferret badgers (Melogale moschata) indicated by epidemiology and the molecular signatures of rabies viruses

Feline herpesvirus vectored-rabies vaccine in cats: A dual protection

In China, cats cause about 5% of human rabies cases. Rabies control in cats plays a role in achieving the ultimate goal of elimination of dog rabies-mediated human deaths. However, there is no cat-specific rabies vaccine in China yet. In this study, we constructed a recombinant rabies vaccine by using a felid herpesvirus 1 (FHV-1) isolate, and deleted the gI/E in the FHV-1 and replaced the region with a glycoprotein (G) of rabies virus (RABV) strain BD06 through homologous recombination. The recombinant virus FHV-RVG was recovered and purified, and the expression of RABV glycoprotein was verified by indirect immunofluorescent assay. For potency in cats, each animal was inoculated intranasally with 1 ml FHV-RVG at 10^6.5 TCID₅₀. Blood samples were collected at defined intervals for antibody titration. The animals were challenged by herpes and rabies after completion of vaccination on day 180 and day 194, respectively. Our results demonstrated all vaccinated cats generated antibodies against both FHV-1 and RABV, and reached an arbitrary protective titer > 0.5 IU/ml for rabies viral neutralizing antibody (VNA) by day 14 post inoculation (dpi) and titer peaked on 30 dpi with VNA at 24.5 ± 10.23 IU/ml. All vaccinated cats presented no clinical signs of FHV-1 infection and survived rabies challenge, while the control cats had severe rhinotracheitis and died from rabies after challenge. All this demonstrated that the FHV-based recombinant vaccine is effective in protection against both FHV-1 and RABV infections.

Oral immunization of mice with recombinant rabies vaccine strain (ERAG3G) induces complete protection

PURPOSE

New rabies vaccine bait for both pets and raccoon dogs residing in Korea is needed to eradicate rabies infection among animals. In this study, we constructed a recombinant rabies virus (RABV), the ERAG3G strain, using a reverse genetics system. Then we investigated the efficacy of this strain in mice after oral administration and the safety of this strain in cats after intramuscular administration.

MATERIALS AND METHODS

The ERAG3G strain was rescued in BHK/T7-9 cells using the full-length genome mutated at the amino acid position 333 of the glycoprotein gene of RABV and helper plasmids. Four-week-old mice underwent one or two oral administrations of the ERAG3G strain and were challenged with the highly virulent RABV strain CVSN2c 14 days after the second administration. Clinical symptoms were observed and body weights were measured every day after the challenge.

RESULTS

All mice showed complete protection against virulent RABV. In addition, cats intramuscularly inoculated with the ERAG3G strain showed high antibody titers ranging from 2.62 to 23.9 IU/mL at 28-day postinoculation.

CONCLUSION

The oral immunization of the ERAG3G strain plays an important role in conferring complete protection in mice, and intramuscular inoculation of the ERAG3G strain induces the formation of anti-rabies neutralizing antibody in cats.