Iycee Charles de Gaulle Summary An Overview Of The West Nile Virus Biology Essay

An Overview Of The West Nile Virus Biology Essay

The plus sense individual strand RNA virus of the genus Flavivirus, is more normally known as West Nile Virus. Flaviviruss are found in semi tropical climes, most notably the Bombay part of India. It is an endemic viral disease arising from the state of India and staying endemic to the part to this twenty-four hours ( 3 ) . Although instances of West Nile Virus have been seen every bit far as the United States, most instances of West Nile virus impacting worlds are found chiefly in the Indian subcontinent ( 3 ) .

The first instances of West Nile Virus were foremost detected over 1000 old ages ago in Equus caballuss arising from sub-Saharan Africa. The virus has a broad scope of hosts that it can infect, from avian species to mammals. Its chief vector, nevertheless is an arthropod mosquito species known as Aedes aegypti and Culex pipiens ( 1 ) . Species become septic when the mosquito vector bites the animate being, thereby go throughing on the virus through blood.

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Once infected most persons exhibit few if any symptoms, nevertheless a choice few Begin to exhibit a high febrility followed by phrenitis and meningitis ( 2 ) . There is no known remedy for West Nile Virus, nevertheless inoculation surveies have been ongoing in order to better combat this viral disease. It is imperative for the people populating in the Indian subcontinent that a legitimate vaccinum be discovered and administered particularly to the immature and aged ( 3 ) . All across the southwesterly part of Asia, the West Nile Virus is an endemic viral disease that causes much hurt to the human population of that country ( 3 ) .West Nile Viruses are of the household Flaviviridae and genus flavivirus ( 1 ) . They consist of a virion size about 45 nanometers in length and a individual strand RNA genomic sequence consisting of approximately 11,000 to 12,000 bases ( 4 ) . This makes the West Nile Virus a medium sized RNA virus. Its cistrons are able to encode about seven non-structural proteins and 3 structural proteins ( 4 ) .

The non-structural proteins of the virus encode the new viral genome and subsequent genomic transcripts. The structural proteins encode proteins that makeup the viral mirid bug every bit good as receptor proteins found on the surface of the virus. The existent form of the West Nile Virus mirid bug is an icosahedron that contains two viral glycoproteins coming out of it ( 4 ) . The full viral mirid bug is surrounded by a membrane produced from the host cell that it enters. As the virus enters the host cell it encompasses the host cell ‘s membrane and envelops itself inside of it.

The envelope environing the virion is made up of a viral protein by the name of E protein, of which there are three separate transcripts ( 4 ) . Whichever copy the specific West Nile Virus contains there are over 180 constructions environing the mirid bug ( 4 ) . Each separate strain of West Nile Virus contains a different combination of E protein which affects different antigen present inside the host organic structure. The virion itself within the mirid bug is spherical with multiple receptor proteins lodging out from it ( 4 ) .

The viral membrane is made up of proteins called M proteins. Both the E and M proteins play a major function in host cell receptor acknowledgment, host cell endosomal membrane merger, and general virion assembly ( 4 ) .Unlike many other virus species, West Nile Viruss are able to undergo perpendicular transmittal in order to last cold, rough seasons ( 6 ) . Female mosquitoes can go through the virus over to their offspring. Adult mosquitoes can besides last the winter season by hole uping in tunnels, caves and sheds ( 6 ) . Transmission of West Nile Virus occurs when a mosquito transporting the virus, besides known as a vector, transfers the disease by lodging its proboscis into a bird, thereby infecting the bird. Birds are known as magnifying hosts because they non merely convey the infection to other birds but besides to other mosquitoes ( 6 ) .

The virus itself enters the host ‘s blood supply and begins occupying host cells via receptor mediated endocytosis. Plus strand RNA viruses like West Nile Virus are fast replicating viruses. The plus individual stranded genome Acts of the Apostless as courier RNA to rapidly transcribe both non-structural and structural proteins ( 6 ) .

The genome is released into the host cell when the pH inside the mirid bug becomes acidic. Then the genome begins to interpret at an ORF site besides known as an unfastened reading frame site on the viral genome ( 4 ) . This forms a viral polyprotein which is so cleaved into the non-structural and structural proteins necessary for virion formation ( 4 ) . Since host cells do non incorporate an RNA dependent RNA polymerase this is besides provided by the virus in order to get down reproduction. The plus sense strand of RNA plants to make subtractions sense RNA which in bend creates more plus sense strands.

In this mode the West Nile Virus can retroflex and make many proteins all within a short span of clip. Once the genome has been replicated it is repackaged into a freshly formed viral mirid bug and exits the host cell by budding ( 4 ) . West Nile Virus is able to infect many different species depending on the types of receptors available on the host cell membrane. In its arthropod vector, nevertheless, West Nile Viruses do non adversely infect its host.

It is merely harboured by the mosquito until a suited transmittal to another species can happen ( 3 ) .Although West Nile Virus is seen to be a rough and enfeebling disease, many worlds affected with the virus have symptomless infections ( 4 ) . They do non demo any physical marks of disease.

West Nile Virus has a comparatively low degree of viraemia during its infection ; hence, it is non seen as infective to other worlds. Human to human transmittal has merely been detected in blood transfusions and organ contribution processs ( 5 ) . Another result of the virus is a mild febrility that occurs when the host organic structure begins to battle the virus by using its immune system to contend off the infection. An result of this immune response is a febrility, in which the organic structure releases cytokines to assail West Nile Virions and let macrophages to take them from the organic structure through endocytosis ( 7 ) . Fevers are the organic structure ‘s manner of assailing and neutralizing the infecting virus. At this phase West Nile Viruses can do concerns, inordinate perspiration, icinesss and overall failing. This phase is known as the viral incubation phase which can last up to a hebdomad. West Nile Viruss can besides do GI jobs, joint hurting, and conceited lymph nodes ( 7 ) .

These symptoms tend to last anyplace from a hebdomad up to two months. A really limited sum of patients end up with the most deadly signifier of West Nile Virus, which is known as a neuroinvasive disease. West Nile Meningitis or West Nile Encephalitis can do the host to sink into a coma. It is difficult to name which patients will stop up at this phase since the early symptoms of meningitis and phrenitis are similar to the early febrile phase ( 7 ) . Once in a coma the patient ‘s survival rate dramatically decreases and their opportunity of decease is really high. The organic structure ‘s immune system continues to battle the virus ; nevertheless, one time the virus ‘s reproduction degree exceeds that of the host ‘s cytokine onslaught, the patient ends up losing their life.Unfortunately, no remedy for West Nile Virus is presently on the market.

Scientists have been pull stringsing mosquito spit mosquitoes someway inoculate themselves and go immune to the virus ( 2 ) . However, after many surveies conducted by the CDC it was observed that mosquito spit, while good to its ain species, serves to rush up the reproduction procedure when mixed in with human blood ( 2 ) . The spit can really worsen the state of affairs and do even more serious symptoms of the disease to look ( 2 ) .

Since no vaccinum is available, people of this part can outdo combat the disease by forestalling its initial entry into their organic structure. Possibly the best signifier of bar is non exposing oneself to mosquitoes ( 7 ) . People show wear long vesture when traveling outdoors and utilize any type of insect repellant they can happen. In 3rd universe states such as India, many people can non afford to pass their money on insect repellant. They should alternatively seek to take any still H2O that is around their places and concerns. Still H2O is the genteelness land for these mosquito species. Keeping a clean and healthy environment and place is besides highly of import. Do non stay out-of-doorss after sundown and usage mosquito cyberspaces to environ the bed so as non to acquire bit while asleep ( 7 ) .

Once spot, nevertheless the lone interventions available are to comfort the symptoms and non bring around the infection itself ( 7 ) . Pain medicine and rehydration are the two chief signifiers of easing a patient ‘s hurt. Without any medicine or medical aid most patients can last since the primary consequence of West Nile Virus is an symptomless infection that leaves the organic structure within a twosome of hebdomads. Many patients may non even know they were infected with West Nile Virus.

In the most badly affected patients, nevertheless, endurance is minimum. Once a patient ‘s encephalon begins to swell it is merely a affair of clip before decease follows.West Nile Virus is particularly deathly to those with a weakened immune system. This includes the aged, the immature and patients susceptible to timeserving infections such as HIV patients.

However, those people that live in high hazard countries, or work during high hazard times such as after twilight are besides at hazard. Anyone can be bit by an septic mosquito at any clip, but these are the demographics of people most at hazard. Recently West Nile Virus has been found to come in the United States as of 1999 ( 6 ) . Now West Nile Viruss are found in countries of Texas, Wisconsin and New Jersey. West Nile septic Europeans as far Ba as 1960, when it arrived in France through Egypt ( 6 ) . However, the part most impacted by the virus remains to be the Indian subcontinent.

Economically, the people of India have lost rewards, and are unable to go on their instruction. The immature may be forced to go forth school and get down occupations at a much earlier age in order to supply for their households and attention for their ill relations. Families can be forced into poorness and whole small towns can be erased if a West Nile Virus eruption occurs.West Nile Virus is endemic to the part of sou’-west Asia. In most instances it is an symptomless infection with a comparatively low hazard of decease. However, in more serious instances it can do phrenitis which brings the patient into a coma and finally decease. This individual strand RNA virus is a plus sense virus that can retroflex instantly upon host cell entry. It is a member of the household Flaviviridae and is a type of flavivirus.

West Nile Viruss are easy going endemic in other countries such as Europe, Africa, and North America. There is no known remedy for the virus, nevertheless scientists do urge preventive steps to battle the disease. It is of import to have on long sleeved vesture and insect repellant when come ining countries known for incorporating mosquitoes. Once infected the lone medicines available are for easing the symptoms caused by the virus and non the virus itself. Rest and plentifulness of fluids to forestall desiccation are some methods to remain healthy ( 7 ) . West Nile Viruses usage arthropod vectors to infect mammal species such as worlds. Although many instances of the disease are symptomless, it is imperative to the people of India that a inoculation be discovered and implemented.

Many dwellers of India are wary of physicians and infirmaries, so their opportunities for endurance are even fewer. The high degrees of decease due to West Nile Virus infections have a negative impact on the Indian economic system. Many people tend to lose their occupations after infection which hinders company promotion and production degrees.

Overall, West Nile Virus is a enfeebling viral pathogen that affects the lives of many worlds all over the universe, but particularly in India.