Influenza DNA
LETHAL INFLUENZA WITH A VIRAL MIMIC
Introduction
Besides all the measurements and the vaccines’ formation against the influenza virus, the infection of the upper respiratory tract still affects the human health contagiously because of the replicating nature of viral DNA. So, there is a need to discover the vaccine that can be more potent and valuable to human health. The most interesting part was the mechanism of the single-cycle swine influenza (H1N1) vaccine against the influenza virus. The most difficult part was to understand the concept of laboratory generation of H1N1/sciV vaccine using different techniques. We do care about the influenza vaccine because, among different influenza vaccines, each has a distinct complication according to the level of age and immunogenicity so the selection is important. Some model organisms include humans, mice, and ferrets. It includes the nasal sera of an individual for evaluation of IgG Abs, protection from the lethal challenge by pHN1 in the individual, evaluation of lung titers, and measurement of survival for 2 weeks.
The key result indicates that the sciV vaccine provides a complete homologous immunity and proves to be a broad spectrum immunoprotective potential against the influenza virus. We know the previously discovered vaccine did not provide complete immunity against the replicating influenza virus. This research could help to develop a vaccine that proves to be completely immunogenic.
We isolate the RNA from infected MDCK cells grown in the Eagles medium. We develop the vaccine of the single-cell infectious influenza virus using the technique of reverse transcription. The receptor binding and the HA gene expressing part of the virus is removed. We took mice and ferrets as an experimental model to study the development of immunization by the sciV. We inoculate the mice with single-cycle influenza H1N1 viral protein to observe the development of immunization. The prime dose of the H1N1 vaccine indicates the formation of Ab titers against the influenza virus proteins. To check the development of the complete immunity, a booster dose was given to the mice at an interval of 2 weeks. The booster dose generates the humoral response in the mouse model. We also observe the presence of CD8 T cells in the lung titers of few convalescent mice models. We took another model of ferrets. We inoculate the non-lethal dose of sciV in ferrets. We demonstrate a low level of seroconversions and observe that there is no presence of viral replications in the nasal passages which proves to block the direct and aerosol transmission of the virus.
Conclusions
By using reverse genetic techniques, a recombinant Influenza virus A was engineered. As it lacks HA gene, it cannot make multicycle replication. Collectively the results which we observe prove that the sciV vaccine generates broad-spectrum immunity in a dose-dependent manner. In addition to this, by using sciIVs alternative methods, we can effectively overcome the efficacy of TIV.
This approach can be really helpful to the scientific community as a single cycle viral protein vaccine brings an outstanding change against the replicating effects of the virus and gives broad-spectrum immunity against an influenza virus potential.
DNA Structure and Replication
1. Why is understanding the structure of DNA and how it is replicated important? List some technologies and practical applications that could not have been developed without this understanding.
The understanding of the structure of DNA and how it replicates is very important as it tells us how the genetic information passes from parents to offspring. By knowing the mechanism of replication, many scientists have struggled to allow selected genes to pass on to the next generation. Many developments that resulted directly from it are genetically engineered foods, making of hybrids, prenatal screening for diseased genes, ability to identify human remains, fingerprinting, testing the physical evidence taken from crime sites, and designing treatments for diseases i.e. AIDS (Dale, Von Schtanz, & Plant, 2011).
2. How does the structure of DNA identified by Watson and Crick differ from the model previously proposed by Linus Pauling and others?
Both models showed that the structure of DNA is in helical form, but according to Watson and Crick, it is double helix while Linus Pauling and Robert Corey reported it a triple helix. The DNA consists of a backbone of deoxyribose sugar units and phosphate groups and side chains of nitrogenous bases of 4 flavors i.e. adenine, guanine, thymine, and cytosine. Watson and Crick showed that the phosphate groups are at the outside of the helix, and nitrogenous bases are present inside and linked with other strand’s nitrogenous bases through hydrogen bonds. While Pauling and Corey had said that the phosphate groups are present inside the helix and nitrogenous bases pointing outwards. Phosphate groups are negatively charged, which would repel each other to drive the structure apart. So this would be impossible under normal conditions of a cell (Watson & Crick, 1953) (Pauling & Corey, 1953).
3. What discovery by Erwin Chargaff helped Watson and Crick build their model of DNA structure? How was this piece of information helpful to them?
Watson and Crick had analyzed data and findings of others to build the double-helical model of DNA instead of doing new experiments. They had collected data of Erwin Chargaff’s experiments done on the DNA of different species. Erwin Chargaff had made conclusions that the amount of purines in DNA was equal to the amount of pyrimidines, the content of A (Adenine) was equal to T (Thymine), and G (Guanine) was equal to C (Cytosine), and the amount of bases varied between species but not among the individuals of the same species. His findings were formulated as the rules of Chargaff in 1951 as A/T = G/C = 1. These findings of Chargaff turned out important to explain the combining of nitrogenous bases in Watson Crick’s model of DNA following the complementary base pairing principle (Watson & Crick, 1953) (Brajuškoviü, Paviüeviü, & Romac, 2013).
4. The conclusion of the paper published by Watson and Crick includes the now rather famous statement: “It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material.” Describe what this statement means and why it is significant.
The complementary base pairing was described by Watson and Crick in their model of DNA. According to this, the sequence of bases in the other strand can be predicted by knowing the sequence in one strand. So, the statement means that Watson and Crick were well aware of the mechanism by which the DNA replicates and transmits information from one generation to another. They told that by understanding the specific base pairing patterns in DNA, it can be predicted how DNA replicates actually. In this mechanism, the two strands of DNA separate and each strand acts as a template for a new double helix.
5. Describe the specific contribution of each of the following researchers to the discovery of DNA structure: a: Francis Crick b: Rosalind Franklin c: James Watson d: Maurice Wilkins
a. Francis Crick was supposed to write a dissertation on x-ray crystallography of Hemoglobin at Cavendish laboratory when Watson arrived. Crick then became a colleague of Watson to research the structure of DNA. They both gathered information regarding nucleic acids and proposed many models of DNA. They published their results in Nature in 1953 in which they explained the double helical-structure of DNA. Crick also described that genetic information transfers to proteins and it cannot be reversed (Watson J. D., Crick, Wilkins, Center Franklin, & Image, 2007).
b. Rosalind Franklin was working at King’s College with Maurice Wilkins and a student, Raymond Gosling in 1952. She had learned X-ray crystallography for many years; that’s why she was an expert in taking photographs of biological materials using this technique. She had taken two high-resolution photographs of the crystallized sample of DNA. The dimensions of DNA were calculated by her. She also deduced that phosphate groups are at the outside of the helical strands of DNA. She was near the discovery of DNA structure but beaten up by Watson and Crick (Watson J. D., Crick, Wilkins, Center Franklin, & Image, 2007).
c. James Watson had heard talks regarding the molecular structure of DNA in 1951 from Wilkins and saw the x-ray crystallographic photographs of DNA taken by Rosalind. It captured his interest. Then he moved to Cavendish laboratory and along with Crick, gathered data of other scientists who worked on nucleic acids. In April 1953, they announced the first time the double-helical structure of DNA and also given the 3-D model of DNA and suggested the replication mechanism. Watson, Crick, and Wilkins were awarded in 1962 with the Nobel Prize for their discovery (Watson J. D., Crick, Wilkins, Center Franklin, & Image, 2007).
d. Maurice Wilkins was working with his mentor John T. Randal at King’s College at that time. It was his idea to study the structure of DNA using X-ray crystallographic techniques. Franklin was appointed by Randal at King’s College for this purpose. Unfortunately, there was not a healthy relationship between Wilkins and Franklin and their progress slowed down (Watson J. D., Crick, Wilkins, Center Franklin, & Image, 2007).
To understand the complementary base pairing in DNA’s structure and to study the contribution of different scientists to help Watson and Crick to deduce the structure of DNA was interesting.
To understand the structure of DNA given by Pauling and Corey was somehow difficult in this case study.
Fingerprinting and the testing of forensic evidence using DNA is most useful for modern science in my point of view.
The molecules containing N15 have high density than the molecules containing the N14 isotope. By centrifuging in a density gradient, the molecules containing N15 will be present at the bottom.
Treatments of many fatal diseases can be found using DNA structure, and genetic material can be introduced into the cells to fight against diseases or kill the abnormal cells.
References
Brajuškoviü, G., Paviüeviü, D. S., & Romac, S. (2013). The 60th anniversary of the discovery of DNA secondary structure. Vojnosanitetski pregled, 70(12), 1165–1170.
Dale, J. W., Von Schtanz, M., & Plant, N. (2011). From genes to genomes: concepts and applications of DNA technology. (3rd ed.). UK: John Wiley & Sons.
Pauling, L., & Corey, R. B. (1953). A proposed structure for the nucleic acids. Proceedings of the National Academy of Sciences of the United States of America, 39(2), 84–96.
Watson, J. D., & Crick, F. H. (1953, April 25). Molecular structure of nucleic acids. Nature, 171(4356), 737–738.
Watson, J. D., Crick, F., Wilkins, M., Center Franklin, R., & Image, B. (2007). The structure of DNA: Cooperation and competition. 1–16.
