Scientists Consider Using Bacteria To Deliver Lethal RNA to Zika Spreading Mosquitoes

MedicalResearch.com Interview with:

Prof Paul Dyson Institute of Life Science Swansea University Medical School Singleton Park Swansea UK

Prof. Paul Dyson

Prof Paul Dyson
Institute of Life Science
Swansea University Medical School
Singleton Park
Swansea UK

Medical Research: What is the background for this study? What are the main findings?

Prof. Dyson: The spread of insect-vectored viruses such as Dengue and, more recently, Zika, underline the urgent necessity to develop new technologies to control insect disease vectors that, due to human activity, are spreading globally. The concept of using RNAi in insects is not new and is widely used as a research tool in the model organism Drosophila melanogaster. However, adapting RNAi for use in non-model insects has been slow, almost entirely due to the problem of delivering interfering RNA to the insect. Manual injection is a less than optimal means of delivery for larger insects, while including interfering RNA in a food source can be effective in smaller insects in the laboratory. But neither delivery system is suited for field applications of RNAi as a biocide. Faced with this challenge, we (myself and Dr Miranda Whitten) conceived the concept of symbiont-mediated RNAi and have advanced it with support from the UK BBSRC and the Gates Foundation, establishing it as a viable mechanism of delivery of RNAi in

(a) a tropical disease vector, Rhodnius prolixus, a vector of Chagas disease, exemplified by targeting insect fertility, and

(b) a globally invasive vector of plant disease, Western Flower Thrips, targeting larval growth. Interfering RNA is actively produced by symbiotic insect bacteria that multiply within the host.

Critical to the technology is to ensure the stability of RNA synthesis by these bacteria. The interfering RNA is then released by the bacteria, absorbed and systemically circulated within the host, thereby causing knock-down of gene expression in specific tissues. We have exploited this technology to severely impair fertility of Rhodnius prolixus, and to cause mortality of developing larvae of Western Flower Thrips. As a biocide, the technology offers exquisite specificity due to the co-evolution and co-dependencies of the symbiont and its insect host, combined with the sequence-specificity of the RNAi. Moreover, development of resistance is highly improbable.

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Link Between Zika Virus, Microcephaly, Stillbirths and Miscarriages

MedicalResearch.com Interview with:
Nancy Dirubbo, DNP, FNP, FAANP
, Certificate in Travel Health, American Association of Nurse Practitioners (AANP) Fellow
Cindy Cooke, DNP, FNP-C, FAANP, American Association of Nurse Practitioners (AANP) President of the Board

Medical Research: Can you provide some background on what is the Zika virus?

Response: Zika virus was first found in monkeys in the Zika Forest of Uganda in 1947 during a research project on mosquito borne viral diseases. From Africa, it spread to India, Indonesia and South East Asia over the next 20-30 years. Not much attention was paid to this illness, as it is often asymptomatic (perhaps as much as 80% of all cases). It causes few symptoms in adults (mild rash, conjunctivitis and headache) and so is often underdiagnosed or misdiagnosed as other self-limiting, viral diseases. Then fast forward to 2015, when a sudden increase in infants born in Brazil with microcephaly occurred and a connection was made with a sharp increase in Zika viral infections, even though the direct mechanism for causing this birth defect is not known. In 2014, there were less than 150 cases of microcephaly in Brazil, and by October 2015, there were 4,700 cases reported.

Medical Research: What is the concern regarding pregnant women and their babies?

Response: The concern for pregnant women is that there appears to be a link between Zika virus and microcephaly, still birth and miscarriages. Children who do survive have severe intellectual disabilities. The virus is most often transmitted by mosquitos, but may also be sexually transmitted. According to the CDC, “Sexual transmission of Zika virus is possible, and is of particular concern during pregnancy. Current information about possible sexual transmission of Zika is based on reports of three cases.” The CDC also recommends, “Men who reside in or have traveled to an area of active Zika virus transmission who have a pregnant partner should abstain from sexual activity or consistently and correctly use condoms during sex (i.e., vaginal intercourse, anal intercourse or fellatio) for the duration of the pregnancy.” It has yet to be determined if Zika virus can be transmitted in other ways, including blood transfusions.

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Incidence of Guillain-Barré Syndrome Rising As Zika Spreads

MedicalResearch.com Interview with:

Dr. Kenneth C. Gorson, MD President Elect GBS|CIDP Foundation International Global Medical Advisory Board

Dr. Ken Gorson

Dr. Kenneth C. Gorson, MD
President Elect GBS|CIDP Foundation International Global Medical Advisory Board
Guillain-Barre syndrome (GBS)
Chronic Inflammatory Demyelinating Polyneuropathy (CIDP)

Medical Research: What is Guillain-Barré Syndrome? What are the main symptoms?

Dr. Gorson: Guillain-Barré Syndrome (GBS) is an immune mediated disorder affecting the peripheral motor and sensory nerves and nerve roots, and is the most common cause of rapidly progressive generalized paralysis in western countries. It is characterized by acute or subacute, progressive, symmetrical limb weakness with distal numbness or tingling in the arms and legs, and reduced or absent deep tendon reflexes in previously healthy patients. Patients notice the sudden onset of difficulty walking, climbing stairs, carrying objects and impaired fine motor skills. Balance is impaired due to sensory loss or weakness and a minority of patients develop facial weakness, trouble speaking and swallowing, and double vision. Severely affected patients may require ventilator support due to respiratory muscle weakness. Symptoms worsen over days to weeks, and most patients reach a maximum deficit (nadir) by 4 weeks, followed by a plateau phase for weeks to months, and then a recovery phase over additional weeks to months. Approximately 80 percent of patients recover to walk with minimal or no residual symptoms or functional disability. Maximal improvement usually occurs by one year, but more severely affected patients may continue to observe subtle improvements for several years after symptom onset.

In approximately two thirds of affected patients there is some preceding triggering event, classically a viral syndrome manifest as a transient upper respiratory or gastrointestinal illness with fever that resolves uneventfully prior to the onset of the neuropathy. Current evidence indicates the pathophysiology of GBS is related to molecular mimicry, where the patient’s antibody response to the preceding infection interacts with a variety of antigens on peripheral nerve myelin or axons producing a generalized but multifocal inflammatory demyelinating process and associated axonal loss in some instances.

The diagnosis is established with nerve conduction studies and electromyography, which shows features indicative of a demyelinating neuropathy affecting multiple motor nerves in the arms and legs. The cerebrospinal fluid protein level is elevated without a cellular response (cyto-albuminological dissociation) in up to 80 percent of patients when performed in the first week of the illness.

Treatment is directed toward the immune response, and several large randomized controlled trials have demonstrated that intravenous immunoglobulin and plasma exchange hasten recovery, and both treatments have similar efficacy.

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Clip-on OFF! Can Kill Zika-Carrying Mosquitos

MedicalResearch.com Interview with:

Christopher Bibbs Anastasia Mosquito Control District Florida

Christopher Bibbs

Christopher Bibbs
Anastasia Mosquito Control District
Florida

Medical Research: What is the background for this report?

Mr. Bibbs: In vector management, the uphill battle is always against the mosquito. And of those, the anthropophilic Yellow Fever mosquito, Aedes aegypti, has become established world-wide as a vector of several emergent diseases. Historically, these mosquitoes carried Yellow Fever and to this day still carry Dengue. Chikungunya, a newly established virus in the Caribbean, has joined the western hemisphere since 2014. And most recently, Zika virus made its way to Brazil and others in South America during 2015. This mosquito thrives in the United States as well, and should a traveler visit a country suffering from these disease and return home sick they risk passing it along to the representative mosquito in your home country.

In order to manage these risks, vector management programs employ an integrated approach using multiple techniques and surveillance tools. But oft-neglected are what is available over-the-counter to consumers wanting relief. One such tool is called “spatial repellents.” By vaporizing a minute amount of chemical into the air, it creates a flight barrier to the mosquito. The mosquito, upon encountering this vapor, will become disoriented and leave the area, thusly reducing bite contact. But as yet these tools are exclusively considered as repellent. But is that all they do?   Continue reading

No Treatment for Zika Infections So Prevention is Key

MedicalResearch.com Interview with:

Mary E. Wilson, MD Visiting Professor of Epidemiology and Biostatistics School of Medicine, University of California San Francisco Adjunct Professor of Global Health and Population Harvard T.H. Chan School of Public Health Boston, Massachusetts

Dr. Mary Wilson

Mary E. Wilson, MD
Visiting Professor of Epidemiology and Biostatistics
School of Medicine, University of California
San Francisco
Adjunct Professor of Global Health and Population
Harvard T.H. Chan School of Public Health
Boston, Massachusetts 

Medical Research: What is the background for this study?
Response: Zika virus infections are spreading explosively in the Americas. This flavivirus infection, spread by Aedes mosquitoes, is new to the Americas, so the majority clinicians have little knowledge of the infection and its potential complications. The country most affected so far is Brazil, where more than a million infections have been reported in less than a year. Infection has also spread to at least 20 other countries in the Americas (the Caribbean, Mexico, Central and South America). Prior to 2007 Zika virus was known to cause infections only in Africa and Asia. Since then, it has spread and caused epidemics in Micronesia, French Polynesia, Easter Island, and since 2015 in Brazil. Most of the movement of the virus from one region to another is via travelers who are infected and then are bitten by mosquitoes in a new region.

In Brazil an increase in cases of infants born with microcephaly (small head) has been noted coincident with the Zika epidemic, and the virus has been recovered from amniotic fluid and from fetal tissue, suggesting that Zika infection during pregnancy may cause microcephaly in the developing fetus. An increase in cases of Guillain-Barre syndrome has also been observed during this and previous outbreaks. Studies are underway to determine if Zika virus is the cause of microcephaly and Guillain-Barre syndrome.In Brazil an increase in cases of infants born with microcephaly (small head) has been noted coincident with the Zika epidemic, and the virus has been recovered from amniotic fluid and from fetal tissue, suggesting that Zika infection during pregnancy may cause microcephaly in the developing fetus. An increase in cases of Guillain-Barre syndrome has also been observed during this and previous outbreaks. Studies are underway to determine if Zika virus is the cause of microcephaly and Guillain-Barre syndrome.

Most countries in the Americas, including the United States, are infested with types of mosquitoes that are competent to transmit the virus, but weather conditions also have to be warm enough to permit the virus to disseminate in the mosquito so that it can be transmitted to another person.

The symptoms of Zika virus infection are typically mild and self-limited  – fever, aches, rash, and conjunctivitis. In fact, the majority of those infected have no symptoms. Because the virus can enter the bloodstream even in asymptomatic infected persons, there is concern that the virus could be spread by blood transfusion, if a person donates blood during the short period (probably a few days at most) when virus is in the blood.

Other reasons for the paper are to highlight what is known about some of the insect repellents and to point out important gaps in our knowledge of their use and urgent research needs.

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