Principles to be followed in vaccine preclinical assay (Part One)

Posted by beauty33 on March 14th, 2019

1. The basic principle for vaccine research  

(1) Meeting the requirements of relevant laws and regulations such as the State Drug Administration Law;

(2) Conducting research on the prevalence of the disease to be prevented, including the degree of hazard of the disease, the type of the population involved, and the type and subtype of the pathogen;

(3) Analyzing the effectiveness, safety and necessity of developing such products for disease prevention;

(4) Studying the benefit-risk ratio of the product used to prevent the disease. According to the possible effects of the preventive program of the product and possible side effects or hazards, the overall trade-offs are evaluated, and measures to avoid or reduce its harmfulness or side effects are proposed. This evaluation will be one of the important basis for the approval of the program.

2. Bacterial strains for vaccine research

The bacterial strain used in the study of the vaccine must be proven to be the bacteria, virus or other pathogen causing the disease. If the strain is isolated from the human body, the following must be clear:

(1). Name and source of the strain:

1. Bacterial strain name
2. Sources of bacterial strains: (1) General conditions of the host strains; (2) Location of the disease, date of onset; date of clinical diagnosis, date of laboratory diagnosis; patient's course and patient outcome.
3. Separation of the original strain of the strain: the name of the tissue of the pharyngeal test, mouthwash, sputum, blood, feces, urine, autopsy specimen; sampling date; the patient's disease period at the time of sampling.
4. In view of the fact that human blood is less infected with a variety of viruses or bacteria at the same time, and samples such as pharyngeal test, mouthwash, sputum, urine, feces, etc. inevitably contaminate other exogenous factors, bacteria isolated from the patient's blood, strain is more suitable for studying vaccines.
5. Names, sources, quantities, sampling methods, etc. of other natural samples of isolates and strains.

(2). Separation process of bacteria and strains

1. Use cells to isolate the virus. The cell name, generation, and source should be clear. Detection of cell sterility, mycoplasma, and external causes should be performed. It is not appropriate to use a tumor-derived cell line for virus isolation. Use non-tumorigenic cells such as human diploid cells or Vero cells whenever possible.
2. The virus is isolated from the animal, and the animal name, strain, grade, age, inoculation route, feeding condition, and animal organ name of the prepared virus species must be described in detail; if the cell is re-adapted, the above-mentioned cell for isolation should also be referred to. Requirements.

(3). Separation and passage characteristics of bacteria and strains

The sample processing method, the first blind transmission confirmed the positive strain of the strain, the method for confirming the strain of the strain, the number of days of culture, the titer of the virus, the titration method, whether the animal is ill or died.

(4). Establishment and preservation of bacterial strains

The original bacterial strain, the titer, the name and concentration of the added protective agent, storage conditions, etc.; the primary bacterial strain refers to cells or medium that have been adapted to produce vaccines, which can stably pass and retain antigenicity. And has been tested for bacterial strains that can be used for vaccine production. The establishment of the seed lot should conform to the requirements of the current edition of the Chinese Pharmacopoeia, “Management Regulations for the Use of Bacterial Species for the Identification of Biological Products”, and the seed batch should be subjected to the passage and limited generation of the bacterial strain to prove the main seed and the working seed. The consistency of the biological characteristics of the batch in the prescribed generation with the original bacterial strain.

(5). Verification of bacterial strains

1. Identification test: serological, biological, nucleic acid sequence analysis and other methods can be used to prove the strain. Identify the gene sequence and structure of the pathogen and other related biomolecules, and analyze the nucleotide and amino acid homology of the main strains in China and clarify the serotype, subtype and/or genotype. Or the prevalence of serotypes. If different serotypes or genotypes exist, the selected serotypes or genotypes should be analyzed and studied for cross-reactivity or cross-protection with other serotypes or genotypes.
2. Sterility examination: According to the requirements of the current edition of the Chinese Pharmacopoeia, it should meet the requirements.
3. Exogenous factor check: According to the relevant requirements of the current edition of the Chinese Pharmacopoeia, it should meet the requirements, and the sampling amount should be sufficient to test the test needs.
4. Amplification capacity and infectious titer: should meet the requirements of smooth production of qualified vaccine according to the production process requirements. Methods and criteria for determining bacterial strain amplification and infectious titers should be established and provide correlation data between these amplification capabilities and infectious titers and vaccine effectiveness.
5. Immunogenicity test: The immunogenicity of the bacterial strain is an important indicator to measure the effectiveness of the vaccine. Effective methods and criteria for determining the immunogenicity of the bacterial strain should be established and established to evaluate whether the candidate strain can be used for vaccine.
6. Attenuating characteristics

(1) If the live attenuated vaccine is developed, the biology, serotype, genotype and immunogenicity of the original strain should be studied; the attenuating method, the attenuating process, the degree of attenuation and the biology and serum after attenuating Type, genotype and immunogenicity, and compare the characteristics before and after attenuation, especially to make a definitive conclusion on the safety and immunogenicity after attenuation;

(2) Verification methods for the attenuation characteristics, animals should be established Model and safety standards after attenuation and the basis for detecting and alerting for virulence responses;

(3) In addition to the detection of general exogenous factors, the live attenuated vaccine for the preparation of injections should also verify the contamination of no retrovirus. The verification method can adopt the PERT method;

(4) If the virus is known to have neurotropic toxicity, the verification requirements can be referred to "IABS Scientific workshop on neurovirulence test for live virus vaccines, WHO, 31 January 2005".

To be continued in Part Two and Three.