Human Viruses

[microbiologybytes]

Why poliovirus replication has been studied for more than 50 years

It’s very rare to find a long term prospective on any science topic being published in scientific journals.

[dglsbgbsnvirus]

Viroids and hepatitis

viroids—the smallest infectious particles known; generally found in plants.

Small size:  Viroids are simply short circular strands of RNA in the range of 250-500 nucleic acid bases.  In contrast, virus RNA strands are ten times larger, 2,000 bases at least.

Human infection:  Human hepatitis D virus is considered a viroid.  It doesn’t code for any proteins, just for its own genome and depends on hitchhiking on Hepatitis B virus particles to propagate.

Hepatitis:  Other than causing inflammation of the liver, the five hepatitis viruses are unrelated to each other. 1.    The hepatitis A virus is a picornavirus; 2.    Hepatitis B virus (HBV) is a DNA virus in the hepadnavirus family. 3.    The hepatitis C virus is a member of the flavivirius family. 4.    Hepatitis D is caused by a viroid. 5.    Hepatitis E, though originally classified in the calicivirius family, now has its own family.

[dglsbgbsnvirus]

CDC Announces Discovery of New Deadly Virus

The Centers for Disease Control and Prevention (CDC)announced Friday they have discovered a new virus that killed an otherwisehealthy man last year in the United States. The agency published the announcement in its Emerging Infectious Diseases journal.

 CDC officials reported the Kansas man had tick bites. After becoming ill, the man was given medication for tick-borne illnesses. When his condition didn’t improve, his blood samples were sent to the CDC. The agency determined the man was infected with an unknown virus. CDC officials eventually linked it to the Thogotovirus group and named it the Bourbon virus. The man quickly developed multiple organ failure and died 11 days after developing symptoms.

CDC officials said they’re working with Kansas health officials to determine if other people are infected with Bourbon virus. They are also researching to better understand the virus and how it is spread.

This is the first time such a virus has caused human illness in the United States. It’s only the eighth time a Thogotovirus has caused symptoms in a person worldwide.  Viruses in this group have been linked to ticks and mosquitoes in Europe, Asia, and Africa.

Thogotovirus is a member of the Orthomyxovirus family, the same family as influenza virus. Like influenza virus it has a genome of six single-strands of RNA.  Most viruses have a genome with a single strand of either DNA or RNA.  Unlike influenza virus which is passed from human to human, the thogotovirus is transmitted by ticks.

[dglsbgbsnvirus]

Paramyxoviruses

Paramyxoviruses--mumps, measles, rubella, etc.

If you want to quantify the alarming impact of the anti-vaccine movement, the chart above is a good place to start. It plots the cumulative number of new measles cases by month, for each year from 2001 to 2014.

There were 644 new measles cases in 27 states last year, according to the CDC. That's the biggest annual number we've seen in nearly a quarter-century. The vast majority of people who contracted the disease were unvaccinated, including the dozens of cases related to an outbreak at Disneyland in Orange County, California, which is basically Ground Zero in our current epidemic of anti-vaccine hysteria.

A 2014 AP-GfK survey found that only 51 percent of Americans were confident that vaccines are safe and effective, which is similar to the proportion who believe that houses can be haunted by ghosts. I don't need to make the case about how harmful these beliefs are -- it's been done plenty of times before, and moreover studies show that arguing with anti-vaxxers only makes them more confident in their beliefs.

But the latest CDC data illustrate the troubling resurgence of a disease that, as of 2000, had been declared eliminated. Anti-vaxxers are quite literally turning back the clock on decades of public health progress.

[23pairsofchromosomes]

Your daily dose of Myoviridae TEM images:

Here’s a nice picture of some Myoviridae phage which infect Salmonella. Generally in the phage world, there are three more common families although others have been found:

Siphoviridae with long flexible tails. (P2 above)

Myoviridae with long contractile tails (T4 above)

Podoviridae with short non-contractile tails. (P22 above)

Phage are first classified based on their morphologies, but bioinformatic information shows the relationships between the families. Typically families of phage are grouped on their appearance as a large amount of the phage genome goes into making the structural proteins.

Myoviridae are quite interesting in the sense that when they bind their host, there are large visible structural changes in the tail region. The tail sheath contracts and the DNA is transported from the head into the bacterium. Other less visible mechanisms are present in the other two morphology types too.

Sam

[ucsdhealthsciences-deactivated2]

Another virus, another worry

Non-polio enteroviruses sound scary and they are quite common. They cause roughly 10 to 15 million infections in the United States each year, according to the Centers for Disease Control. Infants, children and teens are most likely to be affected, primarily because their immune systems haven’t previously been exposed to the pathogen.

Fortunately, enteroviruses typically don’t result in serious illness – think common cold – but there are exceptions. Some people can get very sick. Their hearts or brains may become infected. Despite the “non-polio” in the name, paralysis is a possibility, albeit remote.

One especially rare strain of enterovirus – enterovirus-D68  – is causing concern. In at least 16 states, more than 140 cases of enterovirus-D68 infection have been confirmed, mostly among children. Most patients recover without any treatment, but the virus (which tends to appear in the fall) may worsen breathing problems for some children.

“Children less than 5 years old and children with underlying asthma appear to be at greatest risk of having medical complications from EV-D68, Oklahoma epidemiologist Kristy Bradley, MD, told CNN. “If a child develops a cold or a cough, parents and caregivers should just watch the child a little more closely … if wheezing or asthma-like symptoms develop, medical care should be accessed immediately.”

There is no specific treatment for people with EV-D68, but there are standard precautions you can use to protect against infection. They are useful against similar viruses too.

Wash hands often with soap and water for 20 seconds, especially after changing diapers.

Avoid touching eyes, nose and mouth with unwashed hands.

Avoid kissing, hugging and sharing cups or eating utensils with people who are sick.

Disinfect frequently touched surfaces, such as toys and doorknobs, especially if someone is sick.

[s-c-i-guy]

Ebola

Colorized scanning electron micrograph of filamentous Ebola virus particles (green) attached and budding from a chronically-infected VERO E6 cell (orange).

(25,000x magnification)

source

[sixpenceee]

Luke Jerram makes exact glass replicas of harmful viruses. Each replica is 1,000,000 times the size of the actual virus. From top to bottom we have swine flu, HIV, T4 bacteriophage, malaria, small pox, SARS, HPV & E. Coli. 

[dglsbgbsnvirus]

In the IBOOs, British settlers in Australia imported animals from their homeland, such as red foxes, blackbirds, sparrows, starlings, and rabbits. "They couldn't quite come to grips with gum trees and koalas, explains Brian Cooke, an Australian zoologist. The rabbits lived up to their reputation and reproduced. A lot. Now, Australians can't come to grips with their 200 million to 300 million wild European rabbits, which reside primarily in the southern half of the country. They are an ecological disaster, Cooke says. Unchecked, they create deserts wherever they go, devouring plants, shrubs. and seedlings. They have also forced other small animals, such as the bandicoot, or bilby, a native marsupial, to retreat to northern Australia. Livestock, including sheep and cattle, struggle to compete with rabbits for pasture. Keeping the bunnies in check is a Herculean task. Kill off 70 percent of their population, and they will recoup their losses in a year, Cooke reported in 1991.

In the early 1950s, government sclentists resorted to releasing myxomatosis. a virus that kills rabbits rather painfully. Although quite successful at first , myxomatosis gradually became less effective.  Australian researchers began to test a different virus, a calicivirus. lt kills quickly and fairly painlessly by causing blood clots in the lungs, heart. and kidneys. After completing laboratory tests of the virus' safety and efficacy, the scientists injected it into rabbits quarantined on Wardang Island, an uninhabited spot in Spencer Gulf, South Australia. In late September, they discovered that, despite their efforts, the virus had evaded containment. Dead rabbits with signs of the calicivirus infection appeared outside the pens. Since then, the virus has been found throughout South Australia, Just over the borders of New South Wales and Queensland, and at two sites in central Victoria. It appears to kill between 80 and 95 percent of the adult rabbits it encounters.

For more about rabbits (Lagomorphs).

[dglsbgbsnvirus]

Sea Star Wasting Disease

There is some alarm over an outbreak of Sea Star Wasting Disease (SSWD) characterized by lesions, limb curling and deflation, and death as the animals rapidly degrade or 'melt'. The outbreak began in June 2013 and has killed sea stars from Baja California, Mexico, to Southern Alaska. It might be the biggest marine wildlife epizootic ever observed.

Evidence that SSWD is caused by a virus came from experiments in which extracts of diseased sea stars were passed through a filter with pore sizes small enough to allow passage of viruses but not bacteria or other microbes. When injected into healthy sea stars, these filtrates induced sea star wasting disease.  Analysis of the DNA sequence data revealed the presence of a densovirus (a parvovirus) related to viruses found in Hawaiian sea urchins. The authors called this virus sea star-associated densovirus, SSaDV.

Like other members of the parvovirus family, these are small (25 nm diameter), naked icosahedral viruses with a ~6 kb single stranded DNA genome. When sea stars were infected in the laboratory with filtrates from diseased animals, virus loads, determined by PCR, increased with time together with disease progression.

http://www.virology.ws/2014/11/17/a-virus-that-melts-sea-stars/

[dglsbgbsnvirus]

The biggest viral disease outbreak has nothing to do with Ebola. It is Chikungunya virus, and it is sweeping the Americas.

The incubation period is usually 3 to 7 days, with a range of 1 to 12 days.   The primary symptoms are fever and polyarthralgia [joint pain].

"Chikungunya, in the Makonde language of Tanzania and northern Mozambique, means that which bends over or dries up," said Lyle Petersen, MD, from the US Centers for Disease Control and Prevention (CDC) in Fort Collins, Colorado. 

The reason people bend over is that their joints hurt so bad they cannot walk. The arthralgia is often severe and debilitating, usually bilateral and symmetric, and is most common in the hands and feet. The onset of fever, typically greater than 39 °C [102.2 °F], is abrupt. Patients can also experience headache, myalgia [muscle ache], nausea, vomiting, maculopapular rash [red patches covered with bumps], and arthritis.

 Chikungunya is a mosquito-borne single-stranded RNA virus.   Transmission is from one human to an Aedes aegypti or Aedes albopictus mosquito and then to another human..

 Outbreaks that in retrospect sound like Chikungunya have occurred since the 1700s, but the virus was initially described in a febrile woman in Tanzania in 1953. Since then, numerous outbreaks have occurred in India, Southeast Asia, Africa, islands off Africa, and in the Indian Ocean. Vacationers in the islands then brought Chikungunya back to Italy and France.

The virus has picked up a mutation, that increases its fitness in A. albopictus, a species that can live in more northerly climates than A. aegypti. A. albopictus now has a range extending as far north in the United States as Pennsylvania, Ohio, Illinois, and as far west as Texas and Kansas. This broader range of A albopictus increases outbreak potential in the United States.

 The first cases on the island of St. Martin in the Caribbean were reported in 2013. Outbreaks quickly spread from island to island and then to South America. By July 2014, Chikungunya reached mainland United States. 

To date, 46 states have reported Chikungunya cases (11 locally acquired and 1326 travel-associated) as of October 21, 2014.

Petersen expects to see "millions or tens of millions of cases" of travel-associated cases in the continental United States, but the outbreak potential in the United States will be somewhat limited.

Physicians are far more likely to encounter a patient with Chikungunya at this point than Ebola.

[theeconomist]

Journey into night: The early history of HIV has now been charted in detail

[biovisual]

What does Ebola actually do? By Kelly Servick, 13 August 2014 ||  Science/AAAS | News

Behind the unprecedented Ebola outbreak in West Africa lies a species with an incredible power to overtake its host.

Zaire ebolavirus and the family of filoviruses to which it belongs owe their virulence to mechanisms that first disarm the immune response and then dismantle the vascular system.

The virus progresses so quickly that researchers have struggled to tease out the precise sequence of events, particularly in the midst of an outbreak. Much is still unknown, including the role of some of the seven proteins that the virus’s RNA makes by hijacking the machinery of host cells and the type of immune response necessary to defeat the virus before it spreads throughout the body. But researchers can test how the live virus attacks different cells in culture and can observe the disease’s progression in nonhuman primates—a nearly identical model to humans. 

Continue reading to find out some of the basic things we understand about how Ebola and humans interact …

IMAGE: The Ebola virus THOMAS W. GEISBERT

[micdotcom]

Why the world should care about Ebola in one chart

The United States announced Tuesday it will send 3,000 troops to help tackle West Africa’s Ebola outbreak as part of a new initiative to combat the spread of the disease. Reuters reports that the new plan to combat the disease, which has killed more than 2,500, includes a “major deployment” in Liberia, building 17 new treatment centers, training thousands of healthcare workers and establishing a “military control center for coordination.”

The announcement couldn’t come soon enough. Despite the international community’s best efforts, Ebola may continue to spread out of control. According to alarming new research published in Eurosurveillance, the peer-reviewed publication of the European Centre for Disease Prevention and Control (the EU’s version of the Centers for Disease Control), the world could face 77,181 to 277,124 cases by the end of 2014.

"Let’s not treat it like someone else’s problem"

[dglsbgbsnvirus]

[dglsbgbsnvirus]

enterovirus 68

enterovirus 68—one of a multitude of picornavirus.  Prominent now because it is causing a widespread outbreak of respiratory disease among children.  

Picornaviruses do not have lipid bilayer envelopes but only a naked icosahedral capsid composed of protein.  The genome consists of positive-stranded RNA like mRNA that can be directly translated into protein by host cell ribosome.  Picornaviruses are the smallest of the human viruses )from pico, meaning small, and RNA, ribonucleic acid). They are about 30 nanometers across, slightly bigger than the cross section of a microtubule (25nm).

Traditionally the picornaviruses have been classified according to their symptoms and mode of spread with rhinoviruses spread by entering the nose (from Greek rhino, nose) and enteroviruses (Greek, enteron, intestine) spread by fecal-oral transmission. But, because their genomes overlap so much, virologists turned to a naming system of consecutive numbers: EV68, EV69, EV70, and EV71, etc. rather than the former designations such as polioviruses, Coxsackie, echoviruses, hepatitis A.

Colds are caused by picornaviruses and, in animals, hoof-and-mouth disease. 

[sciencefriday]

Today is World Mosquito Day, which honors the work of Dr. Ronald Ross-the man who discovered that malaria was carried by mosquitoes. But malaria is not the only disease you can get from these nasty bloodsuckers. How can you protect yourself from other diseases like chikungunya?