News » Chapter 13 Bacterial Viruses

Human herpesvirus 6 infection linked to chronic fatigue syndrome (CFS)

Contributed by lyehui on Aug 14, 2013 - 03:59 PM

Chronic Fatigue Syndrome (CFS) is a disorder characterized by extreme tiredness that does not go away with bed rest, lasts for about 6 months in adults. Some of its many other symptoms include cognitive problems, headaches and vertigo. A study in the Journal of Health Psychology also found a high mortality level (12.5%) in CFS patients over the course of 10 years.

Experts believe that CFS has many root causes including psychological factors, pathogens and genetic predisposition.  Recently, a study led by the University of South Florida published under the Journal of Medical Virology suggests that Human Herpesvirus 6 (HHV-6), a common virus, may be a culprit behind some CFS cases.

Cycloviruses could be causing neurological infections

Contributed by aatkinson2 on Aug 10, 2013 - 09:33 AM

According to this article, it seems that a group of viruses known for their circular genome found in a few severe cases in Vietnam and Malawi could be linked to neurological diseases such as brain inflammation. This group of viruses is referred to as cycloviruses. More studies would need to be done to prove the connection between the two.

For the cases in Vietnam, vexed researchers kept coming up short with answers for patients with infected central nervous systems. After considerable diagnostic tests, half of the patients with these types of infections were found with pathogens in them. H. Rogier van Doorn, a clinical virologist, with the help of some fellow workers decided to use next-generation sequencing to hopefully uncover unknown pathogens. After using this latest technique on samples of cerebrospinal fluid from one hundred plus patients, one sample result returned with an interesting clue. A viral sequence from the Circoviridae family, from which cycloviruses are found, was discovered. The researchers went back to the original samples and specifically tested for Circoviridae and uncovered two samples with it. Then, they tested an additional six hundred and forty-two patients with central nervous system infections. The results yielded that about four percent of the patients had this viral sequence in them. Scientists have termed this virus cyclovirus-Vietnam, or CyCV-VN.

Bacteriophage Therapy

Contributed by gsims on Aug 04, 2013 - 05:57 PM

Viruses tend to have a negative connotation to them when in a human health context. What many perhaps do not know is that there are viruses that only attack bacteria. These naturally occurring viruses are called bacteriophages. This article denotes a potentially new way of treating bacterial infections that may be used in the near future. 

When bacteriophages were first discovered, they were thought to be very beneficial to treating infections as they do not target human eukaryotic cells. This research was interrupted by the discovery of antibiotics. Currently, some antibiotic treatments are becoming less effective, especially against Clostridium dificile, an intestinal pathogen responsible for many hospital infections. Bacteriophages are catching the eyes of researchers because they would be able to fight C. dificile infections without harming human cells or the necessary gut microbiota.

Eliminating PRRSV in Pigs

Contributed by kewhitsitt on Aug 04, 2013 - 02:51 PM

Porcine reproductive and respiratory syndrome virus (PRRSV) is costing farmers millions of dollars each year. Upon infection, farmers need to cull their herds due to slowed growth and reproductive issues. Although there is a vaccine available, it is not an ideal solution for this particular disease. The vaccine will not eradicate the virus, only lesson the impact of the disease on farms. Scientists are trying to determine the transmission of the disease, in order to solve the problem. A transmembrane protein CD169 has been identified as a receptor for PRRSV, and was thought to be a required gene for the virus to propagate. In a study conducted by Kansas State University and University of Missouri this theory was disproved. The scientists removed the CD169 gene, and found that the genetically modified pigs were still susceptible to the disease. 

Biggest Virus Yet Found, May Be Fourth Domain of Life?

Contributed by laurenbruehl on Aug 04, 2013 - 10:45 AM

In the past year, scientists came to a shocking discovery when they found a virus larger than any found before: a Pandora virus. Discovered in Chile’s Tunquen River, Pandora viruses average a length of about a micrometer—0.3 micrometers larger than any virus found before—and contain an astonishing 2,500 genes. This is surprising considering an average virus can contain as few as 10 genes. Amoeba are the host for the Pandora viruses

With such a large relative size, one may begin to ask how these relatively enormous viruses went unnoticed for so long. The authors of the study admit that it is entirely possible that they had in fact been discovered before, but were never identified. In addition, other researchers most likely weren’t screening for something that large when looking for viruses. The study authors note that another reason why the Pandora virus had not been found before could be because ocean bacteria are extremely difficult to grow in a laboratory setting; only 10% are able to grow.

Biodiversity in marine viruses

Contributed by tmpernsteine on Aug 03, 2013 - 02:59 PM

While it is understandable that the majority of research on bacteriophages involve human illness and food spoilage, there is an enormous amount of viruses that prey on bacteria in the environment that are still undiscovered. These environmental bacteriophages are very important since they can direct many significant changes in conditions of the natural world such as the flux of carbon and oxygen levels. 

Evolution On the Inside Track: How Viruses in Gut Bacteria Change Over Time

Contributed by keis.yamamoto on Aug 02, 2013 - 09:42 AM

The world is surrounded by microbes that interact with one another competitively or symbiotically, creating a dynamic environment. These interactions occur everywhere, even in our own digestive system. Microbes swarm around the digestive tracts and a myriad of viruses modify key characteristics in bacteria, molding the bacterial population and metabolism. A study led by Fredric D. Bushman, a microbiology professor at University of Pennsylvania, looked at interactions between virus and bacteria in our digestive systems that can ultimately affect humans.

Using Bacteriophages to Fight Bacterial Infections

Contributed by ldejung on Jul 30, 2013 - 09:52 AM

Clostridium difficile is the leading cause of hospital infections in England and Wales, and treating these infections is becoming more difficult as the causative organism becomes more resistant to antibiotics.  Microbiologists are experimenting with the use of bacteriophages, viruses that infect bacteria, as a way to help control these bacterial infections despite antibiotic resistance. 

Friendly Viruses in Mucus

Contributed by qweng on Jul 26, 2013 - 03:11 PM

Most folks would typically consider bacteria to be either good or bad.  The bad such as those that cause infectious disease or the good like the normal flora that aid in digestion, but none would think of viruses having a dual nature as well. A group of scientists led by Jeremy Barr discovered that mucus, a viscid gel-like secretion rich in mucins that act as a protective lubricant from infectious agents, is more than just a barrier. Surprisingly, the active layer of mucus consists of bacteriophages that attack and kill infectious bacteria; such that, Barr later called them “friendly viruses”.  The group also found out that there are more phages in mucus than in mucus-free areas. For example, human saliva harbors about five phages for every bacterium, but mucus directly on the gums host nearly eight times more phages.

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