Prevent Malaria using Virus: Not too far off

Malaria continues to be a major public health concern worldwide, especially in tropical countries. Each year, there are approximately 515 million cases of malaria, killing between one and three million people, the majority of whom are young children in Sub-Saharan Africa. Malaria is a vector-borne infectious disease caused by protozoan parasites (Plasmodium falciparum, Plasmodium ovale, and Plasmodium malariae) belong to the genus Plasmodium. Mosquito is the vector or carrier of these parasites into the human body. Mosquitoes also act as a vector for viruses and caused diseases like yellow fever, dengue fever, epidemic polyarthritis, Rift Valley fever, Ross River Fever, St. Louis encephalitis, West Nile virus (WNV), Japanese encephalitis, La Crosse encephalitis and several other encephalitis. Currently pesticide use and maintaining clean environment are the two most effective preventive measures followed in most of the countries to control the reproduction of mosquitoes. Although some are under development, no vaccine is currently available for malaria.

Is there any way to get rid of mosquitoes and so the malaria? Some people use herbal or chemical based mosquito repellent lotion or oil. The efficacy of mosquito repellent lotions is low and provides very limited protection in terms of duration and number of people. Furthermore, most of us are not ready to accept the mosquito repellent lotions as a replacement to our everyday skin care lotions! So, how to manage this tiny insect? Is there really no way to control them? Until now the answer was “No”. But researchers at Johns Hopkins University are now hoping that mosquitoes can be controlled and that using virus. Researchers have found a new virus that infects the world's most dangerous mosquito, called Anopheles gambiae. This mosquito is the chief malaria vector in Africa. This aggressive human-biter also bites animals and hide in huts. In the PLoS Pathogen journal, scientist described the virus as the first densovirus found in this African mosquito. Although the virus is harmless to the mosquito, but scientists are confident to manipulate the genetic elements of the virus in such a way that once the genetically manipulated virus infects this mosquito, it will reproduce inside the mosquito and will kill them within 10 days. This is good news indeed, although this work could take 5 to 15 years because of the regulatory and ethical barriers to releasing a virus in to wild mosquitoes. Are you ready to wait for 15 or more years to see the viral weapon against mosquitoes or you would consider mosquitoes repellent as a permanent replacement of your lovely beauty lotions to protect yourself from mosquito bite?

Virus infects virus: Mimivirus paradigm

A virus is a sub-microscopic infectious agent that is unable to grow or reproduce outside a host cell. A complete virus particle, known as a virion, consists of genetic material (DNA or RNA) surrounded by a protective coat of protein called a capsid.Viruses infect all cellular life forms and are grouped into animal, plant and bacterial types, according to the type of host infected. Viruses that infect bacteria are known as bacateriophage or simply, phage. Once a phage infects a bacteria, it may have either a lytic cycle or a lysogenic cycle, inside the bacterial cell. A phage that follows a lytic cycle is called lytic phage (virulent phage) and that follow a lysogenic cycle is called lysogenic phage (temperate phage). However, a few viruses are capable of carrying out both lytic and lysogenic cycles, for example, lambda phage. In lytic cycle, the phage (eg. T4 phage) upon entering entering in to the bacterial cell, replicate and lyse (destroy) the bacterial cell. In contrast, in lysogenic cycle the viral genome integrates (or lysogenize) with host DNA and replicate along with it fairly harmlessly, or may even become established as a plasmid and retain inside the bacterial cell. Integrated lysogenic phages are also called propahge. Sometimes prophages may provide benefits to the host bacterium while they are dormant by adding new functions to the bacterial genome in a phenomenon called lysogenic conversion. A famous example is the conversion of a harmless strain of Vibrio cholerae by a phage (CTXØ) into a highly virulent one, which causes cholera.

So far this was all about virus that infects bacteria.

What about virus that infects another virus? There are viruses that infect giant viruses. Marine virologists have reported such small viruses occurring with larger ones in marine protist populations. Small viruses or so called “satellite viruses” require other larger viruses, especially for their reproduction, since they lack essential functions for multiplication. Usually satellite viruses are harmless to their giant virus host. Most recently, La Scola et al. report in Nature (2008) that a small virus, named Sputnik infects a giant DNA virus named Mimivirus (Acanthamoeba polyphaga mimivirus, or APM) and the infection decreases the yield of APM virions and generates APM virions with aberrant morphologies in amoeba cells. Since, unlike usual satellite viruses, Sputnik uses its host’s (Mimivirus) virus machinery and impairs its fitness authors call Sputnik a “virophage.” Sputnik (named after “traveling companion” in Russian) is an icosahedral virus with a DNA genome encoding 21 genes and was isolated in a cooling tower in Paris. Mimivirus once thought to be a bacterium since it contains more number of genes than many bacteria and bear properties like cellular organism. It is five to ten times larger than any other known virus It was La Scola et al. who classified it as a virus in 2003. Discovery of giant Mimivirus and its relation to Sputnik are expected to provide new clues to the virus-virus interaction in virosphere and its impact in the evolution of viruses.