Recombinant Vaccines II: Hepatitis B Overview

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Questions and Answers

What is a primary economic reason for not developing recombinant DNA-derived vaccines?

Traditional vaccines are effective and pose no major adverse reactions. (correct)

Recombinant vaccines require more complex testing.

They are more expensive to produce.

The demand for traditional vaccines is declining.

What scientific challenge is associated with the production of recombinant vaccines?

Some proteins fold improperly in non-mammalian hosts. (correct)

They have a higher rate of adverse reactions.

They cannot be produced in E.coli.

They are always less effective than traditional vaccines.

Which of the following is a risk when using cultured mammalian cells for expressing genes in vaccines?

Production of viral proteins.

Increased production costs.

Induction of tumors when injected into hosts. (correct)

Immediate immune response.

What is a key characteristic of immunity produced by recombinant subunit vaccines?

It tends to be weak and of short duration. Signup and view all the answers

What must be done to avoid the introduction of tumor-causing DNA in recombinant vaccines?

Remove all host cell DNA from the vaccine. Signup and view all the answers

What is the primary method used to produce the recombinant subunit vaccine for Hepatitis B?

Purifying the viral surface antigen or inactivating living virus Signup and view all the answers

Why was yeast chosen as the host for producing the Hepatitis B vaccine?

It was expected to glycosylate the envelope protein Signup and view all the answers

What significant milestone did the recombinant DNA-based vaccine achieve in 1986?

First recombinant DNA-based vaccine licensed for use Signup and view all the answers

What is a primary advantage of recombinant subunit vaccines compared to traditional vaccines?

They can be produced easily, safely, and inexpensively Signup and view all the answers

Which component of the Hepatitis B virus is primarily used for the recombinant vaccine?

S protein Signup and view all the answers

Which drawback is associated with traditional vaccines that recombinant subunit vaccines aim to overcome?

Greater likelihood of side effects due to extra components Signup and view all the answers

What is one of the reasons that not all individuals respond to older vaccines produced in yeast?

Genetic variations in the population Signup and view all the answers

What is a significant disadvantage faced by recombinant subunit vaccines?

They have not fully replaced traditional vaccines Signup and view all the answers

Which of the following statements accurately describes the production of the recombinant Hepatitis B vaccine?

The plasmid containing the S protein gene is introduced into mammalian cells for production Signup and view all the answers

What is the diameter of the self-assembled product of the yeast-produced vaccine?

22 nm Signup and view all the answers

Study Notes

Recombinant and Synthetic Vaccines II

Hepatitis B virus is transmitted via contaminated needles and sexual contact.
It infects an estimated 200,000 Americans annually.
Of the 20,000 who become carriers, one in five dies from cirrhosis and one in 20 develops liver cancer.
Hepatitis B is a viral infection attacking the liver, causing acute and chronic disease.
It is a significant occupational hazard for health workers, but preventable with available vaccines.
A recombinant subunit vaccine exists for Hepatitis B.

Recombinant Subunit Vaccine for Hepatitis B

The virus does not grow in tissue culture but can be obtained from carrier plasma.
Vaccines purify viral surface antigens or inactivate the virus (e.g., with formaldehyde).
The source of these vaccines is limited.
Inactivated vaccines carry a risk of not completely inactivating all particles.

Hepatitis B Virus Structure and Vaccine Components

The virus has small, medium, and large surface proteins (S, S+PreS2, and S+PreS2+PreS1).
The viral envelope is primarily composed of S protein molecules (226 residues).
Its genome is largely double-stranded DNA, encoding core and surface proteins.

Vaccine Production

The gene for the surface protein is cloned from the viral genome.
The DNA coding for the S protein is inserted into a yeast plasmid.
Initially, yeast was used as the host to glycosylate the envelope protein.
The protein is self-assembled into virus-like particles (VLP), which are indistinguishable from actual viral envelopes.

Recombinant Subunit Vaccine Advantages and Disadvantages

Yeast-produced vaccines, while lacking some oligosaccharides, are effective.
In 1986, it became the first recombinant DNA-based vaccine, licensed in the US.
Earlier methods required substantial quantities of human serum to produce one dose.
Modern methods obtain multiple doses from a single yeast culture volume.

Newer Vaccine Generation

Newer vaccines use DNA for PreS2 and PreS1 regions (N-terminal parts).
These regions appear to bolster immunity.

Vaccine Production in Mammalian Cells

Plasmids containing the S protein gene and an animal cell promoter are introduced into mammalian cell lines.
Translation occurs on ribosomes attached to the endoplasmic reticulum.
Proteins are glycosylated and secreted as empty vesicles.
This can induce immunity in individuals unresponsive to older vaccines.

Potential Problems of Recombinant subunit vaccines

Recombinant vaccines, though effective, are often not replacing traditional ones.
Economic reasons: Traditional vaccines are often effective and cause fewer adverse reactions.
Scientific reasons: Some proteins fold improperly.
Expression levels of specific genes can be problematic.
Cultured mammalian cells used to express protective antigens may induce tumors when injected into animals.
Removing host cell DNA can be difficult in order to prevent the introduction of tumor-causing DNA.
Immunity produced is sometimes weak.

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Description

Explore the essential information about Hepatitis B, including its transmission, impact on health, and the role of recombinant subunit vaccines in prevention. This quiz dives into the structure of the virus and the components of the vaccine, highlighting key statistics and occupational hazards associated with Hepatitis B.