Introduction of Literature Review Bunyaviruses

Bunyavirus is actually a range of viruses, which are from the family of Bunyaviridae. There are three segments like small, medium as well as large, which form the genome of bunyaviruses. The single stranded negative sense (RNA) is contained by these segments of bunyavirus genome, and which actually contains ribonucleic acid. A  RNA polymerase enzyme with endogenous aspects is encoded by the genome of bunyaviruses. It is important to mention that in family of bunyaviruses, there are 5 genera’s, which are Hantavirus, Tospovirus, Nairovirus, Phlebovirus, and Orthobunyavirus. The arthropods are the main culprits, who transmit the bunyaviruses in the body such as sand fly, tick or mosquitoes. There is just one exception, which is related to Hantavirus. In this exception case, it is important to mention that Hantavirus is caused by the contact with rats or mice. The viruses transmitted from the bunyaviruses family can cause so many serious diseases to humans like one of the serious ones is called viral hemorrhagic fever (Briese, Calisher and Higgs)

The bunyaviruses family is considered very dangerous as it has vast range of viruses, which can really infect the humans with serious kind of diseases. Different types of diseases are caused by bunyaviruses and one of them is fever of several kinds. For instance, bunyavirus can Crimean-Congo hemorrhagic fever, which can be a cause behind the hemorrhage. There is another fever called rift valley fever, and this fever can be a cause behind the blindness, encephalitis or hemorrhagic hepatitis. The encephalitis can be caused by viruses like La Crosse virus. The Hantavirus pulmonary syndrome, renal failure or hemorrhage can be caused by the Hantaan virus. The other important diseases to be mentioned here are sand fly fever, Oropouche fever, Sin Nombre Virus etc. (Baron)

Detection and Diagnosis of Bunya viruses

There are various techniques used for the detection as well as diagnosis of bunyaviruses. One of the primary techniques is called PCR. This is one of the important molecular biology tools, which help to detect the viruses like the bunyaviruses. There is need to develop some crucial techniques, which an allow to detect these viruses in the bunyaviruses family, and PCR is one of the better ones in this regard, as it has the ability to improve not only virologic surveillance related to mosquito vector, but also clinical diagnosis as well. A technique called reverse transcriptase PCR was used in a study to detect genus Bunyaviruses with 44 viruses’ reactivity. In this technique the primers had total eight pairs. The pairs used for the serogroup was able to detect different viruses which are related to serogroups. In addition to that other primers were used for the detection and identification of viruses related to California encephalitis virus, La Crosse virus, Jamestown Canyon virus as well as snowshoe hare virus etc. By using this PCR technique, the study was able to detect one of the viruses called La Crosse virus, which was infected by the mosquito from the 100 mosquitos’ pool. It shows that when PCR technique is used with proper method and appropriate technique is followed, then various Bunyaviruses can be detected through PCR (Kuno, Mitchell and Chang)

 As mentioned earlier that different kind of techniques are used for different type of Bunyaviruses, and one more technique is called Reverse Transcription–Loop-Mediated Isothermal Amplification (RT-LAMP). According to a study conducted in 2014 for Chinese population, it was found that a new Bunyavirus has evolved it is given the name of Severe fever with thrombocytopenia syndrome (SFTS). It was found that SFTS was happening to be an epidemic kind of infectious disease in the Chinese region. The SFTS was found to be caused by one of the new Bunyaviruses. The average fatality rate in this disease was found to be 12%. This was the new disease so there were no drugs available to treat the patients of SFTS. In this situation, it was crucial to detect the virus and diagnose its root cause, so that it can be controlled as well prevented as early as possible, otherwise fatality rate could increase rapidly (Huang, Hu and Ma)

So, the researchers came up with q quick response by using the RT-LAMP method so that new Bunyavirus can be detected as soon as possible, otherwise situation could get epidemic and more serious. For the tissue culture, a certain limit of detection was used for the RT-LAMP assay, and it was observed during the method that there were no other viruses with cross reactive amplifications to come up with similar kind of clinical manifestations. 138 specimen were taken from suspects of STFS, and 40 hantavirus infection were also used with the evaluation of assay of RT-LAMP was used, and the assay result came up with 97% of agreements as compared to conventional RT-PCR as well as real-time RT-PCR. The process continued with the use of real-time RT-PCR, and it was found that RT-LAMP was 100 percent specific and 99 percent sensitive. It shows that RT-LAMP method was successful in detecting and diagnosing the new Bunyavirus called SFTS, and it also asserted that the method can be used for further research studies as well to find out Bunyaviruses (Huang, Hu and Ma)

One of the other famous methods to detect Bunyavirus is called Enzyme-linked immunosorbent assay (ELISA). In one of the study, it was explained that how Rift Valley Fever from the Bunyavirus family can be detected with the help of ELISA. The affinity chromatography process was used to purify antibodies from the rabbit sera as well as hyperimmune mouse. In this assay technique, the mouse antibody was captured so that its sequences can be related to detect the anti-Rift Valley fever virus with the rabbit. The overall process was successful in to measure the viral antigen in the systems of different kind of animals. The viremic hamster serum was successfully detected by the ELIAS with reliable results. The ELISA was also found positive in detecting the Rift Valley fever infection in the Rhesus monkeys as well. The measurement of viral antigen was also found successful with ELISA in the infected mosquitoes (Niklasson, Grandien and Peters)

 References of Literature Review Bunya viruses

Baron, Samuel. Medical Microbiology. Addison-Wesley, Health Sciences Division, 1986.

Briese, Thomas, Charles H. Calisher and Stephen Higgs. "Viruses of the family Bunyaviridae: Are all available isolates reassortants?" Virology 446.1-2 (2013): 207-216.

Huang, Xue-Yong, et al. "Detection of New Bunyavirus RNA by Reverse Transcription–Loop-Mediated Isothermal Amplification." Journal of Clinical Microbiology 52.2 (2014): 531–535.

Kuno, G, et al. "Detecting bunyaviruses of the Bunyamwera and California serogroups by a PCR technique." Journal of Clinical Microbiology 34.5 (1996): 1184–1188.

Niklasson, Bo Staffan, et al. "Detection of Rift Valley fever virus antigen by Enzyme-linked immunosorbent assay." Journal of Clinical Microbiology 17.6 (1983): 1026-31.