Posts Tagged ‘Infectious disease’

Nanotechnology against malaria parasites

December 13, 2014 Leave a comment

After maturation, malaria parasites (yellow) are leaving an infected red blood cell and are efficiently blocked by nanomimics (blue). (Fig: Modified with permission from ACS)

Malaria parasites invade human red blood cells, they then disrupt them and infect others. Researchers at the University of Basel and the Swiss Tropical and Public Health Institute have now developed so-called nanomimics of host cell membranes that trick the parasites. This could lead to novel treatment and vaccination strategies in the fight against malaria and other infectious diseases. Their research results have been published in the scientific journal ACS Nano.

For many infectious diseases no vaccine currently exists. In addition, resistance against currently used drugs is spreading rapidly. To fight these diseases, innovative strategies using new mechanisms of action are needed. The  Plasmodium falciparum that is transmitted by the Anopheles mosquito is such an example. Malaria is still responsible for more than 600,000 deaths annually, especially affecting children in Africa (WHO, 2012).

Artificial bubbles with receptors

Malaria parasites normally invade human red  in which they hide and reproduce. They then make the host cell burst and infect new cells. Using nanomimics, this cycle can now be effectively disrupted: The egressing parasites now bind to the nanomimics instead of the red blood cells.

Researchers of groups led by Prof. Wolfgang Meier, Prof. Cornelia Palivan (both at the University of Basel) and Prof. Hans-Peter Beck (Swiss TPH) have successfully designed and tested host cell nanomimics. For this, they developed a simple procedure to produce polymer vesicles – small artificial bubbles – with host cell receptors on the surface. The preparation of such polymer vesicles with water-soluble host receptors was done by using a mixture of two different block copolymers. In aqueous solution, the nanomimics spontaneously form by self-assembly.

Blocking parasites efficiently

Usually, the malaria parasites destroy their host cells after 48 hours and then infect new . At this stage, they have to bind specific host cell receptors. Nanomimics are now able to bind the egressing parasites, thus blocking the invasion of new cells. The parasites are no longer able to invade host cells, however, they are fully accessible to the immune system.

The researchers examined the interaction of nanomimics with malaria parasites in detail by using fluorescence and electron microscopy. A large number of nanomimics were able to bind to the parasites and the reduction of infection through the nanomimics was 100-fold higher when compared to a soluble form of the host cell receptors. In other words: In order to block all , a 100 times higher concentration of soluble host  is needed, than when the receptors are presented on the surface of nanomimics.

“Our results could lead to new alternative treatment and vaccines strategies in the future”, says Adrian Najer first-author of the study. Since many other pathogens use the same  receptor for invasion, the nanomimics might also be used against other . The research project was funded by the Swiss National Science Foundation and the NCCR “Molecular Systems Engineering”.

More information: Adrian Najer, Dalin Wu, Andrej Bieri, Françoise Brand, Cornelia G. Palivan, Hans-Peter Beck, and Wolfgang Meier. “Nanomimics of Host Cell Membranes Block Invasion and Expose Invasive Malaria Parasites.” ACS Nano, Publication Date (Web): November 29, 2014 | DOI: 10.1021/nn5054206

New virus isolated from patients with severe brain infections

Researchers have identified a new virus in patients with severe brain infections in Vietnam. Further research is needed to determine whether the virus is responsible for the symptoms of disease.

The virus was found in a total of 28 out of 644 patients with severe brain infections in the study, corresponding to around 4%, but not in any of the 122 patients with non-infectious brain disorders that were tested.

Infections of the brain and central nervous system are often fatal and patients who do survive, often young children and young adults, are left severely disabled. Brain infections can be caused by a range of bacterial, parasitic, fungal and viral agents, however, doctors fail to find the cause of the infection in more than half of cases despite extensive diagnostic efforts. Not knowing the causes of these brain infections makes public health and treatment interventions impossible.

Researchers at the Oxford University Clinical Research Unit, Wellcome Trust South East Asia Major Overseas Programme and the Academic Medical Center, University of Amsterdam identified the virus, tentatively named CyCV-VN, in the fluid around the brain of two patients with brain infections of unknown cause. The virus was subsequently detected in an additional 26 out of 642 patients with brain infections of known and unknown causes.

Using next-generation gene sequencing techniques, the team sequenced the entire genetic material of the virus, confirming that it represents a new species that has not been isolated before. They found that it belongs to a family of viruses called the Circoviridae, which have previously only been associated with disease in animals, including birds and pigs.

Dr Rogier van Doorn, Head of Emerging Infections at the Wellcome Trust Vietnam Research Programme and Oxford University Clinical Research Unit Hospital for Tropical Diseases in Vietnam, explains: “We don’t yet know whether this virus is responsible for causing the serious brain infections we see in these patients, but finding an infectious agent like this in a normally sterile environment like the fluid around the brain is extremely important. We need to understand the potential threat of this virus to human and animal health.”

The researchers were not able to detect CyCV-VN in blood samples from the patients but it was present in 8 out of 188 fecal samples from healthy children. The virus was also detected in more than half of fecal samples from chickens and pigs taken from the local area of one of the patients from whom the virus was initially isolated, which may suggest an animal source of infection.

Dr Le Van Tan, Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, said: “The evidence so far seems to suggest that CyCV-VN may have crossed into humans from animals, another example of a potential zoonotic infection. However, detecting the virus in human samples is not in itself sufficient evidence to prove that the virus is causing disease, particularly since the virus could also be detected in patients with other known viral or bacterial causes of brain infection. While detection of this virus in the fluid around the brain is certainly remarkable, it could still be that it doesn’t cause any harm. Clearly we need to do more work to understand the role this virus may play in these severe infections.”

The researchers are currently trying to grow the virus in the laboratory using cell culture techniques in order to develop a blood assay to test for antibody responses in patient samples, which would indicate that the patients had mounted an immune response against the virus. Such a test could also be used to study how many people in the population have been exposed to CyCV-VN without showing symptoms of disease.

The team are collaborating with scientists across South East Asia and in the Netherlands to determine whether CyCV-VN can be detected in patient samples from other countries and better understand its geographical distribution.

Professor Menno de Jong, head of the Department of Medical Microbiology of the Academic Medical Centre in Amsterdam said: “Our research shows the importance of continuing efforts to find novel causes of important infectious diseases and the strength of current technology in aid of these efforts.”

Journal reference: L.V. Tan et al . Identification of a new cyclovirus in cerebrospinal fluid of patients with acute central nervous system infections. mBio, June 2013. DOI: 10.1128/mBio.00231-13

The above story is reprinted from materials provided by Wellcome Trust, via MedicalXpress.

Biologists Produce Potential Malarial Vaccine from Algae

May 25, 2012 1 comment

Biologists at the University of California, San Diego have succeeded in engineering algae to produce potential candidates for a vaccine that would prevent transmission of the parasite that causes malaria, an achievement that could pave the way for the development of an inexpensive way to protect billions of people from one of the world’s most prevalent and debilitating diseases. Initial proof-of-principle experiments suggest that such a vaccine could prevent malaria transmission.

(up) The edible algae Chlamydomonas, seen here at UC San Diego, can be grown in ponds anywhere in the world. (Credit: SD-CAB)

Malaria is a mosquito-borne disease caused by infection with protozoan parasites from the genus Plasmodium. It affects more than 225 million people worldwide in tropical and subtropical regions, resulting in fever, headaches and in severe cases coma and death. While a variety of often costly antimalarial medications are available to travelers in those regions to protect against infections, a vaccine offering a high level of protection from the disease does not yet exist.

The use of algae to produce malaria proteins that elicited antibodies against Plasmodium falciparum in laboratory mice and prevented malaria transmission was published May 16 in the online, open-access journal PLoS ONE. The development resulted from an unusual interdisciplinary collaboration between two groups of biologists at UC San Diego — one from the Division of Biological Sciences and San Diego Center for Algae Biotechnology, which had been engineering algae to produce bio-products and biofuels, and another from the Center for Tropical Medicine and Emerging Infectious Diseases in the School of Medicine that is working to develop ways to diagnose, prevent and treat malaria.

Part of the difficulty in creating a vaccine against malaria is that it requires a system that can produce complex, three-dimensional proteins that resemble those made by the parasite, thus eliciting antibodies that disrupt malaria transmission. Most vaccines created by engineered bacteria are relatively simple proteins that stimulate the body’s immune system to produce antibodies against bacterial invaders. More complex proteins can be produced, but this requires an expensive process using mammalian cell cultures, and the proteins those cells produce are coated with sugars due to a chemical process called glycosylation.

“Malaria is caused by a parasite that makes complex proteins, but for whatever reason this parasite doesn’t put sugars on those proteins,” said Stephen Mayfield, a professor of biology at UC San Diego who headed the research effort. “If you have a protein covered with sugars and you inject it into somebody as a vaccine, the tendency is to make antibodies against the sugars, not the amino acid backbone of the protein from the invading organism you want to inhibit. Researchers have made vaccines without these sugars in bacteria and then tried to refold them into the correct three-dimensional configuration, but that’s an expensive proposition and it doesn’t work very well.”

Instead, the biologists looked to produce their proteins with the help of an edible green alga, Chlamydomonas reinhardtii, used widely in research laboratories as a genetic model organism, much like the fruit fly Drosophila and the bacterium E. coli. Two years ago, a UC San Diego team of biologists headed by Mayfield, who is also the director of the San Diego Center for Algae Biotechnology, a research consortium seeking to develop transportation fuels from algae, published a landmark study demonstrating that many complex human therapeutic proteins, such as monoclonal antibodies and growth hormones, could be produced by Chlamydomonas.

That got James Gregory, a postdoctoral researcher in Mayfield’s laboratory, wondering if a complex protein to protect against the malarial parasite could also be produced by Chlamydomonas. Two billion people live in regions where malaria is present, making the delivery of a malarial vaccine a costly and logistically difficult proposition, especially when that vaccine is expensive to produce. So the UC San Diego biologists set out to determine if this alga, an organism that can produce complex proteins very cheaply, could produce malaria proteins that would inhibit infections from malaria.

“It’s too costly to vaccinate two billion people using current technologies,” explained Mayfield. “Realistically, the only way a malaria vaccine will ever be used is if it can be produced at a fraction of the cost of current vaccines. Algae have this potential because you can grow algae any place on the planet in ponds or even in bathtubs.”

Collaborating with Joseph Vinetz, a professor of medicine at UC San Diego and a leading expert in tropical diseases who has been working on developing vaccines against malaria, the researchers showed that the proteins produced by the algae, when injected into laboratory mice, made antibodies that blocked malaria transmission from mosquitoes.

“It’s hard to say if these proteins are perfect, but the antibodies to our algae-produced protein recognize the native proteins in malaria and, inside the mosquito, block the development of the malaria parasite so that the mosquito can’t transmit the disease,” said Gregory.

“This paper tells us two things: The proteins that we made here are viable vaccine candidates and that we at least have the opportunity to produce enough of this vaccine that we can think about inoculating two billion people,” said Mayfield. “In no other system could you even begin to think about that.”

The scientists, who filed a patent application on their discovery, said the next steps are to see if these algae proteins work to protect humans from malaria and then to determine if they can modify the proteins to elicit the same antibody response when the algae are eaten rather than injected.

Other UC San Diego scientists involved in the discovery were Fengwu Li from Vinetz’s laboratory and biologists Lauren Tomosada, Chesa Cox and Aaron Topol from Mayfield’s group. The basic technology that led to the development was supported by the Skaggs family. The research was supported by grants from the National Institute of Allergy and Infectious Diseases and the San Diego Foundation. The California Energy Commission supported work on recombinant protein production for biofuels use, and this technology helped enabled these studies.

Story Source:

The above story is reprinted from materials provided by University of California – San Diego.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Journal Reference:

Gregory JA, Li F, Tomosada LM, Cox CJ, Topol AB, et al.Algae-Produced Pfs25 Elicits Antibodies That Inhibit Malaria TransmissionPLoS ONE, 2012 DOI:10.1371/journal.pone.0037179

Novartis Cancer Drugs Fight Deadly Ebola Virus in Lab, Researchers Find

Two Novartis AG leukemia drugs, Gleevec and Tasigna, fought the deadly Ebola virus in laboratory experiments, suggesting the products could be used against a disease for which there are no treatments.

The two medicines stopped the release of viral particles from infected cells in lab dishes, a step that in a person may prevent Ebola from spreading in the body and give the immune system time to control it, researchers from the U.S. National Institute of Allergy and Infectious Diseases wrote in the journal Science Translational Medicine today.

There’s no cure and no vaccine for Ebola, a virus that causes high fever, diarrhea, vomiting and internal and external bleeding. Death can ensue within days, and outbreaks in Africa have recorded fatality rates of as much as 90 percent, according to the World Health Organization.

In some forms of leukemia, Gleevec and Tasigna reduce levels of a protein called Bcr-Abl that causes malignant white blood cells to multiply.

The researchers found that Ebola uses a related protein called c-Abl1 tyrosine kinase to regulate its own reproduction. They showed that by blocking c-Abl1, Tasigna may reduce the pathogen’s ability to replicate by as much as 10,000-fold. In addition to showing how the two drugs might be used to treat infected patients, the findings also suggest that new medicines could be developed to target c-Abl1, they wrote.

Gleevec and Tasigna, also known as imatinib and nilotinib, earned Basel, Switzerland-based Novartis a combined $5.45 billion in sales last year. Gleevec is sold as Glivec outside the U.S.

Source: Yahoo! Health

Cancer Drugs Could Halt Ebola Virus

Some cancer drugs used to treat patients with leukemia may also help stop the Ebola virus and give the body time to control the infection before it turns deadly, US researchers said on Wednesday.

The much-feared Ebola virus emerged in Africa in the 1970s and can incite a hemorrhagic fever which causes a person to bleed to death in up to 90 percent of cases.

While rare, the Ebola virus is considered a potential weapon for bioterrorists because it is so highly contagious, so lethal and has no standard treatment.

But a pair of well-known drugs that have been used to treat leukemia — known as nilotinib and imatinib — appear to have some success in stopping the virus from replicating in human cells.

Lead researcher Mayra Garcia of the US National Institute of Allergy and Infectious Diseases and colleagues reported their finding in Wednesday’s edition of the journal Science Translational Medicine.

By experimenting with human embryonic kidney cells in a lab, they found that a protein called c-Abl1 tyrosine kinase was a key regulator in whether the Ebola virus could replicate or not.

The leukemia drugs work by stopping that protein’s activity. In turn, a viral protein called VP40 stopped the release of viral particles from the infected cells, a process known as filovirus budding.

“Drugs that target filovirus budding would be expected to reduce the spread of infection, giving the immune system time to control the infection,” the study authors wrote.

“Our results suggest that short-term administration of nilotinib or imatinib may be useful in treating Ebola virus infections.”

Imatinib, which is marketed as Gleevec and Glivec, is used to treat chronic myelogenous leukemia in humans, a disease which is caused by dysregulation of c-Abl enzyme.

Nilotinib, also known as Tasigna, has been used in chronic myelogenous leukemia patients who are resistant to imatinib.

Both “have reasonable safety profiles, although some cardiac toxicity has been reported with long-term administration in a small number of patients,” the study added.

According to the UN’s World Health Organization (WHO), about 1,850 cases of Ebola, with some 1,200 deaths, have occurred since 1976.

The virus has a natural reservoir in several species of African fruit bat. Gorillas and other non-human primates are also susceptible to the disease.

Source: Bloomberg

Clinical Syndromes, Laboratory Diagnosis and Treatment of Orthomyxoviruses

February 12, 2012 3 comments

Clinical Syndromes

Depending on the degree of immunity to the infecting strain of virus and other factors, infection may range from asymptomatic to severe. Patients with underlying cardiorespiratory disease, people with immune deficiency (even that associated with pregnancy), the elderly, and smokers are more prone to have a severe case.

After an incubation period of 1 to 4 days, the “flu syndrome” begins with a brief prodrome of malaise and headache lasting a few hours. The prodrome is followed by the abrupt onset of fever, chills, severe myalgias, loss of appetite, weakness and fatigue, sore throat, and usually a nonproductive cough. The fever persists for 3 to 8 days, and unless a complication occurs, recovery is complete within 7 to 10 days. Influenza in young children (under 3 years) resembles other severe respiratory tract infections, causing bronchiolitis, croup, otitis media, vomiting, and abdominal pain, accompanied rarely by febrile convulsions (Table 1). Complications of influenza include bacterial pneumonia, myositis, and Reye syndrome. The central nervous system can also be involved. Influenza B disease is similar to influenza A disease.

Influenza may directly cause pneumonia, but it more commonly promotes a secondary bacterial superinfection that leads to bronchitis or pneumonia. The tissue damage caused by progressive influenza virus infection of alveoli can be extensive, leading to hypoxia and bilateral pneumonia. Secondary bacterial infection usually involves Streptococcus pneumoniae, Haemophilus influenzae, or Staphylococcus aureus. In these infections, sputum usually is produced and becomes purulent.

Although the infection generally is limited to the lung, some strains of influenza can spread to other sites in certain people. For example, myositis (inflammation of muscle) may occur in children. Encephalopathy, although rare, may accompany an acute influenza illness and can be fatal. Postinfluenza encephalitis occurs 2 to 3 weeks after recovery from influenza. It is associated with evidence of inflammation but is rarely fatal.

Reye syndrome is an acute encephalitis that affects children and occurs after a variety of acute febrile viral infections, including varicella and influenza B and A diseases. Children given salicylates (aspirin) are at increased risk for this syndrome. In addition to encephalopathy, hepatic dysfunction is present. The mortality rate may be as high as 40%.

Laboratory Diagnosis

The diagnosis of influenza is usually based on the characteristic symptoms, the season, and the presence of the virus in the community. Laboratory methods that distinguish influenza from other respiratory viruses and identify its type and strain confirm the diagnosis (Table 2).

Influenza viruses are obtained from respiratory secretions. The virus is generally isolated in primary monkey kidney cell cultures or the Madin-Darby canine kidney cell line. Nonspecific cytopathologic effects are often difficult to distinguish but may be noted within as few as 2 days (average, 4 days). Before the cytopathologic effects develop, the addition of guinea pig erythrocytes may reveal hemadsorption (the adherence of these erythrocytes to HA-expressing infected cells). The addition of influenza virus-containing media to erythrocytes promotes the formation of a gel-like aggregate due to hemagglutination. Hemagglutination and hemadsorption are not specific to influenza viruses, however; parainfluenza and other viruses also exhibit these properties.

More rapid techniques detect and identify the influenza genome or antigens of the virus. Rapid antigen assays (less than 30 min) can detect and distinguish influenza A and B. Reverse transcriptase polymerase chain reaction (RT-PCR) using generic influenza primers can be used to detect and distinguish influenza A and B, and more specific primers can be used to distinguish the different strains, such as H5N1. Enzyme immunoassay or immunofluorescence can be used to detect viral antigen in exfoliated cells, respiratory secretions, or cell culture and are more sensitive assays. Immunofluorescence or inhibition of hemadsorption or hemagglutination (hemagglutination inhibition [HI]) with specific antibody can also detect and distinguish different influenza strains. Laboratory studies are primarily used for epidemiologic purposes.

To read more click on this link to the full article: Clinical Syndromes, Laboratory Diagnosis and Treatment of Orthomyxoviruses