Marburg virus
Marburg virus (MARV) is a virus that causes hemorrhagic
fever. It belongs to the Filoviridae family of viruses and is part of the
species Marburg marburgvirus, in the genus Marburgvirus. It leads to Marburg
virus illness in apes, a type of viral bleeding fever. The World Health
Organization (WHO) classifies it as a Risk Group 4 Pathogen (needing biosafety
level 4-equivalent containment). In the US, the National Institute of Allergy
and Infectious Diseases classifies it as a top priority pathogen (Category A)
and the Centers for Disease Control and Prevention categorizes it as a
bioterrorism agent (Category A). It is also classified as a biological agent
for export control by the Australia Group.
The virus can spread through contact with a certain type of
fruit bats or it can spread between people through bodily fluids during
unprotected sexual activity and open wounds. The illness can lead to bleeding,
high body temperature, and other signs that are like those of Ebola, which is
from the same group of viruses. The WHO says there are no authorized vaccines
or antiviral medication for Marburg. However, getting prompt and expert
treatment for symptoms such as dehydration greatly improves the chances of
survival.
Marburg virus was initially reported in 1967. It was
identified in that year during a series of outbreaks of Marburg virus disease
in the German cities of Marburg and Frankfurt and the Yugoslav capital
Belgrade. Employees in the lab came into contact with the infected tissues of
grivet monkeys at Behringwerke, a large industrial facility in Marburg that was
previously a part of Hoechst and later became a part of CSL Behring. In the
outbreaks, thirty-one individuals caught the infection and seven of them passed
away.
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The virus is one of two members of the Marburg marburgvirus
species, which is part of the Marburgvirus genus, Filoviridae family, and
Mono nega virales order. The Marburg virus is named after the city of Marburg in
Germany, where the virus was first found, and the word virus used in taxonomy.
The Marburg virus was initially named this in 1967. In
2005, the name of the virus was changed to Lake Victoria marburgvirus, creating
confusion as the only difference in distinguishing between a Marburg virus
organism and its species as a whole is the use of italics, as in Lake Victoria
marburgvirus. However, the majority of scientific papers still used the name
Marburg virus. As a result, in 2010, the Marburg virus was given its name back
and the species name was altered.
STRUCTURE:
Marburg virions are made up of seven structural proteins.
In the middle is
the spiral rib nucleocapsid,
which is made up of the genetic RNA wrapped around a
polymer of nucleoproteins (NP). The ribonucleoprotein is connected to the RNA-dependent
RNA polymerase (L) along with
the polymerase cofactor (VP35) and a transcription activator (VP30). The
ribonucleoprotein is enclosed in
a matrix, created by
the primary (VP40)
and secondary (VP24)
matrix proteins. These tiny pieces are enclosed by a fat layer made from
the cell membrane of the host. The
membrane attaches to a
glycoprotein (GP) that extends 7
to 10 nm spikes from its surface. Although very similar in structure, marburgvirionsare different in terms of antigens compared to ebolavirions.
EVOLUTION:
The viral types are categorized into two groups: Ravn
virus and Marburg virus. The Marburg types can be further classified into
two subgroups: A and B. The A strains were found in Uganda
(five from 1967), Kenya (1980) and Angola (2004–2005) while the B strains were
from the Democratic Republic of the Congo epidemic (1999–2000) and a group of
Ugandan isolates found in 2007–2009.
The average rate of evolution for the entire genetic code was
3.3 × 10−4 substitutions per site per year, with a credibility interval
of 2.0–4.8. The Marburg variations had an average root
time of the most recent common ancestor of 177.9 years ago (with a 95% highest
posterior density of 87–284), indicating an origin in the mid
19th century. On the other hand, the Ravn strains can
be traced back to an average of 33.8 years ago (around the
early 1980s). The likely place where the Marburg
virus originated was Uganda, while the place where the
RAVV originated was Kenya.
MARV is one of two types of Marburg viruses that can lead to
Marburg virus disease (MVD) in humans, which is also commonly known as
Marburg hemorrhagic fever (MHF) in literature. Another virus
is called Ravn virus (RAVV). Both viruses meet the requirements to be part of
the Marburg marburgvirus species because their genetic makeup differs from
the original Marburg marburgvirus or the Marburg virus variant Musoke
(MARV/Mus) by less than 10% at the nucleotide level.
Prevention:
The initial medical trial to assess the effectiveness of
a Marburg virus vaccine took place in 2014. The research experimented with
a genetic vaccine and found that people who received the
vaccine showed a certain amount of antibodies. However, these
vaccines were not anticipated to give complete immunity. Various animal
models, including hamsters, mice, and non-human primates (NHPs), have demonstrated effectiveness in
Marburg virus research. Mice are helpful in the beginning stages of
vaccine development because they are good models for diseases in
mammals. However, their immune systems are different from humans, so it is necessary to also test vaccines
on other mammals. Among these models, the infection in macaques appears to
be the most comparable to the effects in humans. Several different
vaccines have been taken into account. Virus replicon
particles (VRPs) were found to work well in pigs, but did not work well in guinea pigs but did not work as well when tested
on NHPs . Furthermore, a deactivated virus vaccine was
not successful. DNA vaccines exhibited some effectiveness in
non-human primates, but all vaccinated individuals displayed indication of infection.
Due to the fact that Marburg virus and Ebola virus are from the
same family, Filoviridae, some researchers have tried to develop a
vaccine that can be given in a single shot for
both viruses. This would make the vaccine easier to use and reduce the
cost for developing countries. Using a one-shot vaccine has been
shown to not produce any negative which is
the potential immune response to vaccination, when compared to
two individual vaccinations.
On June 23, 2022, scientists at the Public Health Agency of Canada completed a
study that demonstrated positive outcomes of a recombinant
vesicular stomatitis virus (rVSV) vaccine in guinea pigs, named PHV01. Based on
the research, receiving the vaccine about one
month before being infected with the virus offered strong protection.
