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Objective To evaluate the safety and immunogenicity of lyophilized, live attenuated hepatitis A vaccine (H2 strain) in rhesus monkeys Methods Nine adult rhesus monkeys were used as experimental animals The rhesus monkeys without anti HAV were divided randomly into the aqueous vaccination group (4 rhesus monkeys), the lyophilized vaccination group (3 rhesus monkeys), and the control group (2 rhesus monkeys) Monkeys were inoculated by intramuscular injection, with control monkeys being inoculated with Minimum Essential Medium Eagle (MEM) Following vaccination, the monkeys were observed for the development of diarrhoea and other adverse side effects, such as changes in appetite, frequency of defaecation and stool consistency for seven days At the weeks 2, 3, 4, 6, 8, 10 and 12 positnoculation, the peripheral blood was collected from all animals and assayed for anti HAV and alanine aminotransferase (ALT) and aspartate aminotransferase (AST), at weeks 0, 4 and 8 postinocuation, needle biopsy specimens were taken at weeks 0, 4, 8 and 12, all monkeys were sacrificed and tissue samples were taken from liver, lung, heart, kidney and brain for pathological examination at week 12 Results Animals were immunized with a dose of 7 0 logTCID 50 /ml which is stable after freeze drying During the 12 week observation, no animals showed abnormal elevations of liver enzymes (ALT and AST) and no change in appetite or activity Two monkeys (one in the aqueous group and the other in lyophilized group) showed possible lesions at week 8 The lyophilized vaccine, in addition to eliciting an anti HAV IgG response similar to aqueous vaccine ( P >0 05), also showed IgM anti HAV response at week 2 which was not observed with aqueous vaccine Conclusions These results demonstrate that lyophilized, live hepatitis A vaccine is safe and highly immunogenic in primates, supporting its further evaluation in human clinical studies
Objective To evaluate the safety and immunogenicity of lyophilized, live attenuated hepatitis A vaccine (H2 strain) in rhesus monkeys were used as experimental animals The rhesus monkeys without anti HAV were divided randomly into the aqueous vaccination group (4 rhesus monkeys ), the lyophilized vaccination group (3 rhesus monkeys), and the control group (2 rhesus monkeys) Monkeys were inoculated by intramuscular injection, with control monkeys being in molded with Minimum Essential Medium Eagle (MEM) Following vaccination, the monkeys were observed for the development of diarrhea and other adverse side effects, such as changes in appetite, frequency of defaecation and stool consistency for seven days At the weeks 2, 3, 4, 6, 8, 10 and 12 positnoculation, the peripheral blood was collected from all animals and assayed for anti HAV and alanine aminotransferase (ALT) and aspartate aminotransferase (AST), at weeks 0, 4 and 8 postinoc uation, needle biopsy specimens were taken at weeks 0, 4, 8 and 12, all monkeys were sacrificed and tissue samples were taken from liver, lung, heart, kidney and brain for pathological examination at week 12 Results Animals were immunized with a dose of 7 0 logTCID 50 / ml which is stable after freeze drying during the 12 weeks observation, no animals showed abnormal elevations of liver enzymes (ALT and AST) and no change in appetite or activity Two monkeys (one in the aqueous group and the other in lyophilized group showed possible lesions at week 8 The lyophilized vaccine, in addition to eliciting an anti-HAV IgG response similar to aqueous vaccine (P> 0 05), also showed IgM anti HAV response at week 2 which was not observed with aqueous vaccine Conclusions These results demonstrate that lyophilized, live hepatitis A vaccine is safe and highly immunogenic in primates, supporting its further evaluation in human clinical studies