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Lassa Viruse Fever Structure

Lassa virus fever is a disease that is very common and endemic in West Africa which according to the CDC infects 100,000-300,000 per year with approximately 5,000 deaths [1]. This highly contagious and extremely virulent viral disease was first discovered in a town in the Yedseram river valley called Lassa (which is where it got its name from) in Borno state, Nigeria. Its first case was recorded in 1969 after two nurses died in a hospital in Lassa town. It is an acute viral hemorrhagic fever that is endemic not only in Nigeria, but to other West African countries like Congo, Liberia, Sierra Leone and Guinea [2]. At least two cases have occurred in the United States, both of which of course both individuals traveled to countries endemic to this disease. Lassa virus is zoonotic but it can also be transmitted from person to person. No vaccine has been developed for this virus but only one drug is known and used to successfully treat the disease.
Lassa virus is a member of the Old World complex and is classified under the family of arenaviridae. The genus classification is arenavirus and its species is its name; Lassa virus. It belongs to Group five (V) in the Baltimore classification of viruses alongside Ebola, measles, rabies and influenza. Viruses in this category are negative-sense single stranded RNA genomes and have sandy appearances due to the presence of ribosomes [3]. The virions are spherical and comprise of an envelope and two nucleocapsids which have filaments that form a circle. The capsid is enveloped. The envelope contains glycoproteins that post translationally cleave to Glycoprotein1 and 2 (GP2). GP2 interacts with nucleocaspid protein to assemble virion. It also acts as the viral fusion protein under acidic conditions [4]. Other proteins found in the cell include nucleocapsid protein which is the most abundant and the first protein that is expressed in an infected cell. The second protein that is expressed is the viral RNA-dependent- RNA polymerase which can be detected in virions. Its genome is composed of two strands namely S-RNA and L-RNA. S-RNA is ambisense and codes for two proteins; glycoprotein and nucleoprotein while L-RNA is a negative sense RNA and codes for Zinc RING-finger motif protein (Z) and Viral RNA dependent RNA polymerase (L) [4].
The life cycle of a typical Lassa virus starts when the virion comes in contact with the cell. The virus takes over the cell mechanism and uses it to its advantage by utilizing the cell’s replication machinery to make more viruses that will cause infection in other cells. The cellular receptor called alpha-dystroglycan binds with the viral receptor called GP1 and infects the cell. The virus enters the cell through endocytosis which is rare with enveloped viruses [5]. The capsid is uncoated due to low Ph (acidity) of the endosome and then transported to the cytosol. Replication is very rapid. Copies of the mRNA minus sense genomes are made and these genomes then make viral complementary RNA copies of itself which are plus sense. Nuclear proteins are expressed in large quantities followed by the replication of L and S strands being ensued. Enveloped glycoprotein is expressed and this differentiates into GP1 and GP2 which then migrate to the surface of the cell. Nucleocapsid proteins combine with genomic RNA to form strings of bead-like structures. The nucleocapsid proteins cross-links to the carboxy terminus of GP2. The virus is assembled in the cytoplasm after which it egresses the cell by budding out [5].
Lassa virus is zoonotic which means that humans become infected when they come in contact with an animal that is infected. The animal in this case is a rodent called Mastomys natalensis commonly known as multimammate rat. Infected rats are asymptomatic to this disease but they shed it in their urine and droppings and also secrete it in their saliva, all which can be aerosolized [1]. Humans get infected from direct contact with these materials like consumption of contaminated food, touch infected objects and even inhalation of tiny infected particles. It can also be tramsmitted from person to person. This can occur if a person comes in contact with excretions, blood, and secretions of an infected person. Lassa virus affects nearly all the tissues in the human body, starting with the mucosa and eventually the vascular system. Arenaviruses are able to infect macrophages and possibly cause the release of mediators of cell and vascular damage. T-cell induced immunopathologic effects significantly exacerbate tissue destruction. Once infected, the virus can find its way into the human body through different mediums like the respiratory tract, the blood stream and/or lymph vessels. It then duplicates in the reticuloendolethial cells causing capillary lesions. These lesions further lead to platelet and erythrocyte loss and sometimes cause hemorrhage in various organs [6].
About 80% of people infected with this virus are asymptomatic. After and incubation period of about 21 days, symptoms that are not specific like fever, chest pain, nausea, vomiting malaise, abdominal pain and coughing begin to occur. Some patients experience symptoms like diarrhea, protein in the urine, facial swelling, encephalitis, seizures, facial swelling, tremor and disorientation may occur in the late stages. If fetal or left untreated, it can lead to death. Mortality rate is about 15-20% among hospitalized patients and about 95% among pregnant women. However, abortion reduced death among pregnant women because the virus has a high affinity for the placenta and the survival of the fetus in 10% regardless of any measure taken [1]. The most common long term consequence of Lassa fever after recovery is deafness which occurs in one-third of the cases. Deafness could range from mild to severe and could become permanent. Spontaneous abortion is another common consequence. It is often diagnosed by using ELISA which detects IgG, IgM antibodies and also Lassa antigens. This viral infection cannot be cleared by the immune system because it is systemic and cause hemorrhagic fever.
Ribavirin, an antiviral drug is the only drug that is used to treat Lassa virus in its early stages. It works by interfering with the viral replication by blocking RNA-dependent nucleic acid synthesis [7]. Patients should receive supportive care which includes maintenance of appropriate body fluid, oxygenation and treatment of opportunistic and complicating infections. No vaccine is available for this diease. Lassa virus can be prevented if contact can be avoided between humans and the multimammate rat especially in regions when outbreaks are known to occur. Proper storage of food in rodent-proof containers is highly recommended. Also, keeping homes clean, disposing trash far away from household, keeping cats and using rat traps in order to avoid attraction of these vectors can greatly reduce susceptibility [2]. The complete eradication of Mastomys is almost impossible because these rodent reservoirs are widely distributed and are very abundant in endemic areas. People caring for patients with Lassa fever should avoid direct person to person contact especially with blood and bodily fluids of patients. Other precautions like using sterilized equipments, wearing masks, protective clothing, gloves, face shields, closed-toe shoes and goggles should be worn before coming in contact with infected patients. Infected patients should be isolated from uninfected patients as well. Educating people in endemic areas on ways to reduce rodent population in their homes and surroundings, personal hygiene, developing more rapid diagnostic tests and also making Ribavirin readily available to the population can help to address the threat of this disease.
Lassa virus infects males, females and even children of all age groups. People who are at risk of contracting the infection include those that live in or frequently visit areas that have a high population of Mastomys who are infected with the virus. This includes places with poor sanitation and/or overcrowded living conditions. Those that work at health care facilities are also at risk if proper precautional measures are not taken. Studies show that 300,000 – 500,000 cases of Lassa fever occur annually and out of which 5,000 deaths are recorded. Death usually occurs with 14 days of occurrence in fetal cases. This disease is fetal in women who are late in pregnancy and mortality rate is as high as 80% in the third trimester. In Liberia and Sierra Leone, 10-16% of patients that are admitted in their hospitals suffer from Lassa fever which expresses the impact of this dieases in those areas. The most promising approach to developing a vaccine so far is Vaccinia vectored Lassa genes. They have been successfully tested on guinea pigs and primates but it has not been tested on humans.
Lassa virus is an acute viral hemorrhagic fever that is highly endemic in West Africa. It is a zoonotic disease that is transmitted to humans when they come in contact with urine, droppings or excretion of waste products from Mastomys Natalensis commonly known as the ‘multimammate rat’. The virus does not affect the rats. Infected rats serve as carriers of the Lassa virus because they are asymptomatic throughout their life time. Lassa virus affects nearly all the tissues in the human body. Person to person transmission can also occur if proper caution is not maintained. Symptoms of this disease range from fever to encephalitis and if fetal, death can occur. Mortality rate is from 15-20%, however, it is significantly higher in pregnant women. Deafness is a common long term consequence of this disease after recovery. Ribavirin is the only drug that is known to treat this disease and it is only successful if used when the infection is in its early stages. No vaccine is available. Preventive measures to avoid this being infected this disease include avoiding contact with rodent vectors, proper storage of food and water, isolation of infected patients and taking proper precautionary measures when health care workers treat infected patients. Lassa virus affects people of all ages. It is almost impossible to eradicate this viral infection because the multimammate rat is abundant in endemic areas.

Oxygen Production During Photosynthesis

Meera Kapadia and Amirah Mohd Ariff
Abstract
The purpose of this experiment was to investigate the role of light in the production of oxygen gas through photosynthesis. The independent variable for this investigation was the time elapsed between recordings of the location of the sodium bicarbonate edge; the dependent variable was the displacement of the sodium bicarbonate edge; and the control for this investigation was the height of the Elodea plant, which was four centimeters for each test tube, and the distance between the light source and the test tubes. Of the four test tubes used in this experiment, three contained Elodea in sodium bicarbonate solution; therefore, only one test tube without Elodea was prepared. The test tubes containing the Elodea were placed under three different conditions–receiving light from a white light bulb, receiving light from a white light bulb while being covered by aluminum foil, and receiving light from a blue light bulb. The distance traveled by the sodium bicarbonate from the initial point in the bent glass tubing was recorded for five, five minute intervals. The results indicated that the white light bulb set up had the highest rate of photosynthesis. However, some of the results obtained, including data which indicated that photosynthesis cannot occur in the presence of blue light, were not as expected, but occurred due to systematic errors in the vacuum seal breaking and the sodium bicarbonate edge moving toward the test tube. This would imply that photosynthesis consumes oxygen instead of produces it. Still, the alternative hypothesis which was light is a necessity in the production of oxygen during photosynthesis was supported.
Introduction
In order for an entity to be considered alive it must meet five requirements–be able to metabolize, be composed of cells, process genetic information, work towards reaching the ultimate goal of self-replication, and continuously evolve (Freeman, 2). Focusing on energy metabolization raises the question, how do organisms that are alive, then, acquire energy? There must be a mechanism engineered by evolution to convert light energy into the chemical energy required by all organisms to survive. For living organisms, the primary process for initially acquiring energy and converting it to a useable form is known as photosynthesis which can be summarized as follows:
6CO2 6H2O light energy→C6H12O6 6O2
where “plants harvest the kinetic energy in sunlight and store it in the bonds of carbohydrates” (Freeman, 80). Since only plants are able to photosynthesize, they are known as autotrophs that produce the energy that is cycled through the rest of the biosphere.
Through photosynthesis, plants are able to produce two necessities for survival required for humans–oxygen gas and usable energy in the form of food. Since photosynthesis provides humans with the essentials for survival, research is being conducted on how the rate of photosynthesis can be improved. In “Genetic modification of photosynthesis with E. coli genes for trehalose synthesis,” a 2004 study, Nicotiana tabacum was transformed with E. coli genes to improve the rate of photosynthesis per unit of leaf area (citation). It was found that changes in the photosynthesis levels were due to trehalose 6-phosphate content rather than trehalose. This result was analyzed for growth patterns, and it was found “a greater photosynthetic capacity did not translate into greater relative growth rate or biomass” since photosynthetic capacity was found to be negatively related to leaf area (citation). Overall, this experiment highlighted the complexities of photosynthesis regulation which affects the lives of all humans.
Even though the mechanism for energy conversion is known, several questions still arise regarding the location of photosynthesis, the extent of its efficiency, and most importantly, what conditions are preferred in order to maximize the rate of photosynthesis. Focusing on the final question posed, this investigation studied to what extent Elodea plants are able to photosynthesize in the presence of different types of light and conditions by measuring oxygen gas output. The null hypothesis was that light is not a required reactant for photosynthesis to occur. The alternative hypothesis was that the rate of photosynthesis is directly proportional to the amount of light available. From this, it can be predicted that the greater the amount of light available, the greater the oxygen output; ergo, the greater the rate of photosynthesis.
Materials and Methods
The materials needed for the apparatus of this experiment were four test tubes, a test tube rack, Elodea plants, bent glass tubing, a stopper, a beaker, water, a graduated pipette, aluminium foil, saturated sodium bicarbonate solution, a stopwatch, parafilm and clamp lights with two different colored bulbs.
The independent variable for this investigation was the time elapsed between recordings of the location of the water edge. The dependent variable was the displacement of the water edge. The control for this investigation was the height of the Elodea plant, which was four centimeters for each test tube, and the distance between the light source and the test tubes.
Four centimeters of Elodea were cut toward their stems, placed into two test tubes, and covered with saturated sodium bicarbonate solution. To test whether plants only photosynthesized in the presence of light, one of the test tubes were covered with aluminum. The third test tube was filled with only sodium bicarbonate solution; thus, it acted as a negative control. In order to ensure that no external oxygen would enter the test tube, bent glass tubing was inserted through a rubber stopper and covered with parafilm; thus, the apparatus was vacuum sealed. Some excess solution was displaced and visible in the bent tube when the stopper capped the test tube. This step was taken in order to measure the outward displacement of the oxygen that would indicate that photosynthesis had, indeed, occurred.
Before the test tubes were placed in front of the light source, a beaker filled with water was placed in between the light source and the empty test tube rack. The test tubes were then placed in the test tube rack about 30 cm away from the light source. These steps were taken to to ensure that the Elodea plants were not damaged due to direct light. The system was calibrated for five minutes. Next, the light was turned on and the displacement of the water edge after each five minute interval was recorded. This procedure was repeated for the final test tube with blue light as the light source.
Results
Table 1:
The Distance Traveled of The Sodium Bicarbonate Solution From The Initial Point (cm)
Conditions
Time 0 (0 mins)
Time 1 (5 mins)
Time 2 (10 mins)
Time 3 (15 mins)
Time 4 (20 mins)
Time 5 (25mins)
Elodea and concentrated Sodium Bicarbonate Solution
0.00
0.10
0.15
0.15
0.20
0.30
Elodea and concentrated Sodium Bicarbonate Solution, covered with aluminium foil
0.00
0.05
0.05
0.05
-0.10
-0.10
Concentrated Sodium Bicarbonate Solution without Elodea (control)
0.00
0.00
0.00
0.00
0.00
0.00
Elodea and concentrated Sodium Bicarbonate Solution, with a blue light source
0.00
0.00
0.00
0.00
0.00
-0.15
Table 1: The table above displays the displacement of the sodium bicarbonate for each five minute interval.
Figure 1:

Figure 1: This figure displays the rate of photosynthesis under varying conditions for four different test tubes.
The data collected indicated that the test tube that contained Elodea and concentrated sodium bicarbonate solution placed under white light, which encompasses the entire visible light spectra, had the greatest displacement of the solution from the initial point. During the first five minute interval, the sodium bicarbonate solution displaced 0.10 cm from the initial point, 0.15 cm after 10 minutes, 0.15 cm after 15 minutes, 0.20 after 20 minutes, and 0.30 cm after 25 minutes. The test tube that did not contain Elodea indicated no change in sodium bicarbonate location in the 25 minute duration of the experiment. The third test tube placed under white light containing both elodea and concentrated sodium bicarbonate while being covered with aluminum foil showed a displacement of 0.05 cm during each of the first three five minute intervals. However, the displacement decreased to -0.10 cm during the fourth time interval interval, 20 minutes after the experiment began, and remained constantly at this value for the rest of the experiment. When the Elodea plant’s ability to photosynthesize in the presence of blue light (~500 nm) was tested in a test tube containing concentrated sodium bicarbonate, there was no evidence of displacement for 20 minutes (citation). After 20 minutes elapsed, however, the solution indicated that it had been displaced 0.15 cm in the negative direction.
Discussion
Since oxygen was only visibly produced in the presence of light, the null hypothesis, that the rate of photosynthesis is unrelated to the availability of light was not supported. The alternative hypothesis, however, that the rate of photosynthesis is directly proportional to the amount of light available was supported. This is because light energy acts as a reactant in the reaction of photosynthesis which produces organic carbohydrates that store energy that is used to make ATP that provides energy to plants (Freeman, 81). Evidence of light being a requirement for photosynthesis was seen in the test tube that contained both the Elodea plant, sodium bicarbonate, and was exposed to the white light. In Figure 2, the slope of the Elodea and concentrated sodium bicarbonate solution stayed positive during the entirety of the experiment. This shows that the rate of oxygen production was increasing as time increased which gave evidence that photosynthesis was actively occurring. The importance of light was further emphasized by the results found in the test tube that contained the Elodea plant and sodium bicarbonate, the factory of photosynthesis and its raw materials, but was covered by aluminum foil. The light never reached the inside of the test tube where the Elodea and sodium bicarbonate were, so the plant did not have the energy to conduct photosynthesis. However, as evident from the trendline of the Elodea in the concentrated sodium bicarbonate solution covered by aluminum, it seems that there was an initial oxygen output before it decreased to a negative rate of oxygen production. This can be attributed to systematic errors in which the vacuum seal applied to the test tube was applied incorrectly. A dysfunctional seal could have caused the location of the sodium bicarbonate to vary in the bent glass pipette.
References
Freeman, Scott, et al. 2014. Biological Science, 5th ed.; Pearson Education, Inc.
Mclean. Laboratory Exercises for General Biology 1. 3rd ed. Plymouth: Hayden-McNeil, 2015. Print.

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