Respiratory Syncytial Virus Infection: A Comparison of Nanoparticle Vaccines with Traditional Vaccines - Assignment Example

Antigenic preparation Generation of Virus-like nanoparticles (VLP) can be done through assembling of structural proteins and lipid bilayer membranes that are similar morphologically to the virus. From recent research, DNA transfection of avian cells was used to generate a chimeric Newcastle disease virus NDV core-protein VLP (Ko et al, pg.3). This had the RSV F and G ectodomains. Development of IgG2a antibodies, T helper cytokine response occurred when DNA vaccine encoded with either RSV F or G was introduced. In a neonatal mouse model, a combination of RSV F DNA and protein vaccines induced F-specific antibodies response and cytokine CD8 T cell response (Gregory et al, pg.1). Then inactivated RSV since 1960 have been prepared by inactivating infected cells (kidney cells) With formalin and then concentrated by alum precipitation and ultracentrifugation. Then these were tested in infants and children. Live attenuated RSV were developed after the failure of parenteral administration of FI-RSV (Ko et al, pg.3). This was accelerated when the importance of local immunity in preventing RSV was discovered. This led to intranasal immunization to trigger the immune system. Unfortunately, it has been discovered that the intranasal live attenuated vaccine can replicate and lead to infection in the infants Recent research has shown that infectious virus can be recovered from c DNA clones of RSV. This has led to genetically engineered vaccines. Through this, the following two-subunit vaccines have been isolated: RSV F and RSV G. They are the viral glycoprotein inducing neutralizing and protective antibodies (Gregory et al, pg.1). Therefore, they have been considered potential for vaccine preparation. With the chimeric RSV FG vaccine, they contain immunoaffinity-purified glycoprotein with the ectodomains of RSV F and G (Ko et al, pg.3). RSV FG administered intramuscularly has shown protection of lower respiratory tract from infection and not the upper respiratory tract. Synthetic peptide vaccines have been derived from bacterial expression in prokaryotes same to F and G glycoprotein. The effect of both vaccines on the human immune system VLP have been shown to raise RSV neutralizing titre and ultimately control the lung viral load. When a comparison on the immunological trigger of antibodies was done between VLP and Formalin inactivated (FI-RSV), traditional vaccine, using ELISA coating antigen. After the first infection, the levels of IgG antibodies specific for RSV were high in FI RSV than in VLP. However, three weeks after priming (second dose) the level of antibodies was high in VLP. Therefore, making VLP is a better vaccine because after the second exposure the antibodies levels go high (Ko et al, pg.3). One of the crucial factors of any RSV vaccine is RSV neutralization activity in relation to the body immune. VLP exhibits high levels of RSV neutralizing activity compared to traditional vaccine. However, both of them demonstrated ability to control RSV replication in the lungs after RSV infection. Upon RSV infection, the use of traditional vaccination (FI-RSV) for RSV have demonstrated high cellular infiltration of large size cells including the granulocytes, monocytes and macrophages in the cell of the alveoli and bronchioles. Similar results were obtained when live RSV is used (Gregory et al, pg.11). However, the VLP demonstrate a lower level of cellular infiltration in the cells of alveoli and bronchioles. Unlike the inactivated RSV that leads to high level of eosinophils, the VLP have not been associated with increased levels of eosinophils upon RSV infection. Research has demonstrated that inactivated RSV shows a higher level of myeloid marker CD11bn + compared to VLP at the fifth day. This was through analysis of bronchoalveolar lavage (BAL) fluids. However CD11c+are found to be higher than in VLP than FI-RSV group. CD11C+ is associated with the macrophages (Graham, pg.149) Studies have demonstrated that VLP immunization increases the ratio of adaptive CD8+/ CD4+ cells secreting interferon (IFN-γ ) in the BAL lymphocyte (Riedel et al, pg.21). interferon are have both detrimental and beneficial effects, therefore there level should balance to avoid detrimental effect after recovering from the RSV infection.CD4+ have been linked with enhancing the disease and protecting the lungs. Therefore, CD4+/CD8+ balance should be maintained (Gregory et al, pg.1). The inactivated RSV vaccine induced high level of CD4+ in the BALF after an RSV infection. Through this, the immune system would control the RSV from replication (Yildiz et al, pg. 905. Additionally, CD8+ and CD4+ level being high in the VLP, then the level of controlling the replication. CD8+ has been seen to offer more protection compared to CD4+.the use of inactivated RSV is associated with an increase in Th2 cytokines (IL4, 3 and 13). These cytokes have been linked with inflammatory RSV disease. Studies have demonstrated with evidence that VLP confers protection against RSV through modulating cellular phenotypes, cellular infiltration, inhibits pulmonary eosinophilia, modulate interferon gamma release as well as induce cytokines and Th1 type antibodies. VLP vaccination produces antibodies that recognize RSV and bind ton RSV protein antigen. After priming, the level of IgG2 increases (Graham, pg.146). Boost immunization the level of IgG2 relatively increases. Application challenges and limitations There is inadequate vaccine or treatment available for RSV. The following are some of the major challenges in the development and application that Graham found out in application of the nanoparticle vaccine. These include first, the RSV infection sets in at early age. Second, it has ability to evade the innate immunity. Third, there is failure of the natural infection to trigger immunity that can confer protection when it occurs again (Yildiz et al, pg. 905). Fourth, legacy of vaccine illness, the failure of the animal models to imitate the same pathogenesis inhuman RSV and the ethical issues imposition remain a challenge to the vaccines availability (Graham, pg.151) Compare traditional vaccines and nanoparticle vaccines in terms of RSV prevention The nanoparticles vaccine are specific therefore immunogenicity specific. This makes them safe to human being unlike the traditional vaccines that were hardly specific. The nanoparticle vaccines are easier to produce than the live whole vaccine (Gregory et al, pg.11). Read More