Safety And Immunogenicity Of Tetanus Diphtheria

Advantages and Disadvantages of Viral Vaccines

Discuss about the Safety and Immunogenicity of Tetanus Diphtheria.

The discipline of immunology is incomplete without vaccination. The concept of vaccination was developed via the pioneering efforts of Edward Jenner and Louis Pasteur and has helped in the eradication of small pox and polio (Baron, 2014; Smith, 2013). Vaccination has also reduced the rate of occurrence of diseases like, measles, mumps, rubella, diphtheria, tetanus, pertussis (whooping cough) (Munoz et al., 2014). The development of vaccines begins with simple research. However, recent advancement in the field of immunology and molecular biology has paved the foundation of effective novel vaccine. B-cell and T-cell epitope have enabled immunologist to design new age vaccines which can maximise both the arms of immune system, active immunity and passive immunity (Patronov & Doytchinova, 2013).

There is always a need for development of vaccines against infectious diseases. Each year millions of people die round the world because of deadly viral disease, HIV-AIDS. According to World Health Organisation, 34 million in world is suffering from HIV (De Cock, Jaffe & Curran, 2012). The first viral vaccine was designed via cloning a gene for major surface antigen of the Hepatitis B virus (HBsAg). The process undertaken was recombination, the recombinant yeast containing HBsAg has shown to generate protective antibodies against hepatitis B worldwide (Yu, 2016).

Viral vaccines are generated out of inactivated virus or attenuated virus (alive but devoid of pathogenecity or devoid of disease causing capability) (Pica & Palese, 2013).

The failure of seasonal influenza vaccine to protect against the influenza infection had augmented the requirement for the discovery of the cross-reactive influenza vaccine that can elicit immunity against different subtypes of virus including newly emerging pandemic virus. The cross-protective vaccines like whole inactivated virus (WIV) vaccine, targets conserved internal antigens like the matrix protein or nucleoprotein of the virus and thereby preventing viral proliferation inside the body (Budimir et al., 2012). This inactivation can be done via several chemical compounds. The inactivated viral vaccine for West Nile virus (WNV) has been generated via the application of hydrogen per-oxide (H2O2) as an inactivating agent. The inactivated or attenuated vaccine thus produced is safe and immunogenic and is capable to protecting against WNV (Pinto et al., 2013).

Other principal form of viral vaccines includes viral vector vaccines. Viral vector vaccines can be developed via using fowl poxvirus (FPV) and herpes virus of Turkey (HVT) as principal vectors carrying infectious laryngotracheitis virus (ILTV) genes. It is wide used in the poultry industry of USA for commercial purpose (Vagnozzi et al., 2012).

Vaccine production

Live-attenuated viral vaccine has several advantages. For example, live attenuated respiratory synctial virus (RSV) vaccine offers multiple advantages when used for immunization of young and infant children. This vaccine does not generate vaccine-associated enhanced RSV disease. Under the immunity wing, they generate innate, cellular and humoral immune response. This activation of immunity occurs in both systemic and local form. The generation of cellular and humoral immune response promote the generation of memory response thereby helping to fight against the recurrent infection in future. Moreover, this vaccine, does not cross-react with the passively acquired maternal antibody in the upper-respiratory tract (Karron, Buchholz & Collins, 2013). Another form of the viral vaccines is RNA vaccines. The major genetic material of virus is RNA and hence it is used as an important component for viral vaccines. The RNA vaccines are made using mRNA transcript or via using self-amplifying RNA replicons. They have the potential to overcome the limitations associated with plasmid DNA and viral vectors (Ulmer, Mason, Geall, & Mandl, 2012). Viral vector-based vaccines can increase the immunogenicity in the absence of an adjuvant. It also induces a robust cytotoxic T lymphocyte (CTL) response that helps in eliminating virus-infected cells (Ura, Okuda & Shimada, 2014).

Live attenuated vaccines have certain disadvantages. There lies a risk of these live attenuated vaccines to undergo recombination to generate virulent natural recombinants. For example, recombination between herpes viruses have been observed both in-vitro and in-vivo experimental conditions and thus has generated safety concerns regarding the application of the attenuated herpes virus vaccines, both for human and for veterinary use. The disease generating out of recurrent reactivation causes lifelong chronic infection (Lee et al., 2012).

Hepatitis B remains a significant global health problems inspite of availability of effective and safe vaccine. The low cost, orally derived hepatitis b vaccine can alleviate problems like perpetuating infection-transmission cycle.

Figure: Hepatitis B vaccine production via bioencapsulation of HBsAg

(Source: Hayden et al., 2012)

The most common secondary immuno-deficiency is acquired immunodeficiency syndrome of AIDS. It is caused by human immunodeficiency virus 1 (HIV-1). The rapid proliferation of the virus causes instant establishment of a systemic, large viral population, which is capable of dynamic adaptation under every immune selection pressure. These viruses always remain one-step ahead than the host immune system. Moreover, the virus replicates indefinitely in vast majority of infected individuals (Idele et al., 2014). Recent advancement in medical science has provided evidence that the initial stages of viral infection via mucosal transmission are comparatively vulnerable to immune intervention. This concept has lead to the development of vaccine strategy that can elicit responses against the early stages of viral infection (Picker, Hansen & Lifson, 2012). Other diseases associated with viral vaccine are influenza, measles mumps rubella (MMR), chicken pox, hepatitis B (Bennett, Dolin & Blaser, 2014). Here lies the importance of the viral vaccines as it helps in the treatment of the deadly diseases, which caused recurrent infections and are fatal.

Disease associated with viral vaccines

Conclusion

Thus from the above discussion it can be concluded that viral vaccine occupy a significant portion of vaccine development in immunology. There are different types of virus vaccines used like live attenuate viral vaccines and viral vector vaccines. The successful use of the vaccines has been proved helpful to reduce the incidence of several diseases. However, more research studies are required to be undertaken in order to generate ethically safe viral vaccines for the treatment of deadly viral disease like HIV AIDS.

References

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