A collaboration between Professors Paul Lehner (CIMR, Department of Medicine) and John Sinclair (Department of Medicine) has shown that changes identified in cells latently infected with HCMV make them targetable chemotherapeutically which could eventually lead to novel strategies to eliminate latently infected cells – something which could not have been considered a decade ago.

Read the full article: Weekes et al., 2013,  Science, 340: 199-202

image: www.freeimages.co.uk

Salary:  £27,854-£36,298 pa

Closing date: 3 May 2013

Reference: RC01147

Murray Clarke has previously shown that death of vascular smooth muscle cells (VSMCs) leads to unstable atherosclerotic plaques – the primary cause of heart attacks and stroke. VSMC necrosis is incredibly inflammatory and drives plaque growth, whilst necrosis of other cell types is relatively silent. However, the mechanisms underlying such specificity were previously unknown. Murray’s work, recently published in Immunity, has revealed that an intracellular form of a receptor that usually resides on the cell surface binds the inflammatory cytokine IL-1α and inhibits its activity. The aim of his Senior Fellowship is elucidate how and why the receptor is intracellular in only certain cell types and whether its absence is a key molecular change that drives the chronic inflammation responsible for plaque growth.

It was in Los Angeles in 1981 that the first report emerged of an unusual cluster of patients whose immune systems appeared to have failed. This report is now acknowledged as the first scientific account of an infectious disease that was to become the HIV/AIDS global epidemic, infecting 60 million people and killing 25 million to date.

Three decades later, and with more than 20 antiretroviral drugs to combat HIV, treatment can now significantly prolong life and reduce the rate of viral transmission. For some patients, life expectancy with uninterrupted treatment is now similar to that of someone who is not infected with HIV – not the death sentence it once was – and the global rate of new infections is at last declining.

Yet, current therapies do not fully restore health and, in resource-poor settings, patients often lack access to antiretroviral drugs. Moreover, because the virus has the ability to insert its genetic material into the genetic material of the patient’s cells, ‘latent’ viruses can re-emerge at any point, necessitating lifelong drug treatment.

“There is no imminent prospect of a vaccine, and there may not be one in the way that we have for measles and mumps, where our own immune system can clear the virus,” explained Andrew Lever, Professor of Infectious Diseases in the Department of Medicine and Honorary Consultant Physician at Addenbrooke’s Hospital. “The bottom line is 60 million immune systems have had a crack at eradicating HIV and all have failed.”

The virus is both adaptable and versatile, escaping drug treatment by mutating the structure of its proteins. Patients require combinations of drugs – an approach known as highly active antiretroviral therapy (HAART) – because this reduces the chance that a virus will mutate sufficiently to escape all.

Continued research efforts are therefore urgently required, as Lever explained: “The big areas in HIV research are finding new drugs to complement the ones we’ve got already, so as to outrun the virus in terms of resistance, and finding a means to eradicate the latent virus.”

Lever’s research, which has been investigating the mechanisms of HIV infection for almost 25 years, is helping to tackle both of these challenges.

Structural traps

Anti-HIV drugs typically target viral proteins that are involved in the process of entering or exiting the cell. But, as Lever explained, this lies at the heart of resistance to the virus: “Proteins are very adaptable. Time and again the virus escapes the drug by altering its protein structure so that it still functions but the drug no longer recognises it. We decided instead to target the virus’ RNA genetic material.”

Lever’s previous studies had provided fundamental insights into the way in which RNA is packaged, a process that he realised could provide a remarkable opportunity for a completely new type of antiretroviral therapeutic.

For the virus RNA to be packaged and released from the cell as an intact virus particle, it must twist itself into a three-dimensional knot-like structure. It was this structure which Lever and colleagues discovered is used as a packaging signal by the virus. To form the structure, the sequence of the RNA must be highly conserved between viruses. As a result, opportunities for ‘escape mutation’ are limited. A virus protein called Gag uses the knot-like structure to pick out the viral RNA from the thousands of cellular RNAs that are an integral part of the process by which a cell translates the information in its DNA into molecules that enable the cell to function.

Interfering with Gag binding can potentially stop the virus spreading from cell to cell. In collaboration with Professor Shankar Balasubramanian and Dr Neil Bell in the Department of Chemistry, and researchers at the University of Sussex, Lever is now using this phenomenon as the basis for designing novel antiviral drugs. In parallel, work with Professor David Klenerman in the Department of Chemistry is providing the first high-resolution data on the precise conformation of the RNA structure.

The goal is to create a ‘structural trap’ in which small-molecule drugs lock the RNA in a conformation that can no longer interact properly with Gag. Targeting the function of RNA through its 3D structure is a new direction for antiviral drug discovery, and sufficiently challenging to receive funding from the Medical Research Council Milstein Fund – specifically intended for ‘high-risk, high-reward’ studies.

Using an assay they developed for measuring the interaction between Gag and RNA, the team is now screening a library of small drug-like molecules for those with potential to interfere with the process. “Although it’s very early stages, the molecular hypothesis that we started with for targeting this structure has taken us to a situation where we have molecules that look like they are doing something interesting in the assay,” said Balasubramanian. “Being able to target RNA in this way would be a paradigm shift in terms of new therapeutics for HIV, and other infectious diseases.”

Will RNA-directed therapeutics overcome viral resistance? “It’s a good question and untested,” added Balasubramanian. “Once we find a good small molecule that disrupts binding and packaging then we can address exactly this question.”

Curing HIV

Drug discovery is a key area for the future. However, the scientists also have their eyes on an even bigger prize – a cure for HIV – and a new collaboration between five UK Biomedical Research Centres (BRCs) is now working towards understanding how to rid the body of latent virus.

“Because latent virus exists only as genetic material, essentially indistinguishable from the genetic material of the patient’s cells, it’s effectively hidden. The patient’s immune system can’t see these infected cells and the drugs can’t target them,” explained Lever. “The reservoir of infection sits there for years because it’s in very long-lived immune cells. Even if you suppress the virus right down using drug treatment, as soon as you stop the drugs it bounces right back with viruses that, based on their genetic sequence, are historically very old, so these have been latent for a long time.”

The new project, CHERUB (Collaborative HIV Eradication of Viral Reservoirs: UK BRC), funded by the National Institute for Health Research, brings together researchers from Imperial College, King’s College Biobank, University of Cambridge, University College London and University of Oxford, and is the first pan-BRC cooperative project to compete internationally in a new field of biomedical research.

Lever leads the Cambridge contribution along with Dr Mark Wills and Dr Axel Fun from the Department of Medicine. “Until we learn how to eradicate the latent virus then all we can do is contain it,” Lever explained. “CHERUB will work in collaboration with NHS Trusts and the pharmaceutical industry to recruit new patient cohorts for studies that range from fundamental laboratory research through to large-scale clinical trials of novel agents.”

The Cambridge researchers will develop an assay to detect latent virus that will be used to provide a measure of the relative success of drugs, as well as expand current research areas to learn new ways to rouse the virus from its latency.

“All HIV patients have latent virus – it’s a fact of life,” added Lever. “You can suppress active viruses with current conventional drugs so that the patient’s immune system recovers but you can’t get rid of the latent virus. The aim now is to suppress the virus to the point where the immune system recovers but at the same time to wake up and eradicate the virus from the latently infected cells. And then we are talking about a cure.”

For more information, please contact Louise Walsh at the University of Cambridge Office of External Affairs and Communications.

This article originally appeared on the University of Cambridge website here.

Follow the link to the full article.

The study, funded by the British Heart Foundation (BHF), Medical Research Council (MRC) and Wellcome Trust, outlines a way for scientists to get the cells they need to make induced pluripotent stem (iPS) cells (3) from a routine blood sample. Previously scientists have struggled to find an appropriate type of cell in the blood that can be turned into a stem cell, and often make iPS cells from skin or other tissues, which can require a surgical procedure, like a biopsy.

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Researchers from the the University of Cambridge, the Wellcome Trust Sanger Institute, and Cambridge University Hospitals used advanced DNA sequencing technologies to confirm the presence of an ongoing outbreak of methicillin-resistant Staphylococcus aureus (MRSA) in a Special Care Baby Unit in real time. This assisted in stopping the outbreak earlier, saving possible harm to patients. This approach is much more accurate than current methods used to detect hospital outbreaks.

Using this technology, the team revealed that the outbreak had extended into the wider community, a conclusion that could not be reached with available methods. They also used sequencing to link the outbreak to an unsuspecting carrier, who was treated to eradicate MRSA.

“We are always seeking ways to improve our patient care and wanted to explore the role that the latest sequencing technologies could play in the control of infections in hospitals,” says Dr Nick Brown, author, consultant microbiologist at the Health Protection Agency and infection control doctor at Addenbrooke‟s Hospital Cambridge. “Our aim is to prevent outbreaks, and in the event that they occur to identify these rapidly and accurately and bring them under control.

“What we have glimpsed through this pioneering study is a future in which new sequencing methods will help us to identify, manage and stop hospital outbreaks and deliver even better patient care.”

Over a six month period, the hospital infection control team used standard protocols to identify 12 patients who were carrying MRSA. However, this standard approach alone could not give enough information to confirm or refute whether or not an ongoing outbreak was actually taking place.

In this study, the researchers analysed MRSA isolates from these 12 patients with DNA sequencing technology and demonstrated clearly that all the MRSA bacteria were closely related and that this was an outbreak. They also revealed that the outbreak was more extensive than previously realised, finding that over twice as many people were carrying or were infected with the same outbreak strain. Many of these additional cases were people who had recent links to the hospital but were otherwise healthy and living in the community when they developed a MRSA infection.

While this sequencing study was underway, the infection control team identified a new case of MRSA carriage in the Special Care Baby Unit, which occurred 64 days after the last MRSA-positive patient had left the same unit. The team used advanced DNA sequencing to show in real time that this strain was also part of the outbreak, despite the lack of apparent links between this case and previous patients. This raised the possibility that an individual was unknowingly carrying and transmitting the outbreak MRSA strain.

The infection control team screened 154 healthcare workers for MRSA and found that one staff member was carrying MRSA. Using DNA sequencing, they confirmed that this MRSA strain was linked to the outbreak. This healthcare worker was quickly treated to eradicate their MRSA carriage and thus remove the risk of further spread.

“Our study highlights the power of advanced DNA sequencing used in real time to directly influence infection control procedures,” says Dr Julian Parkhill, lead author from the Wellcome Trust Sanger Institute. “There is a real health and cost burden from hospital outbreaks and significant benefits to be gained from their prevention and swift containment. This technology holds great promise for the quick and accurate identification of bacterial transmissions in our hospitals and could lead to a paradigm shift in how we manage infection control and practice.”

In this instance, DNA sequencing was a key step in bringing the outbreak to a close, saving possible harm to patients and potentially saving the hospital money.

“Our study indicates the considerable potential of sequencing for the rapid identification of MRSA outbreaks,” says Professor Sharon Peacock, lead author from the University of Cambridge and clinical specialist at the Health Protection Agency. “What we need before this can be introduced into routine care is automated tools that interpret sequence data and provide readily understandable information to healthcare workers. We are currently working on such a system.

“If we have a robust system of this type in operation when the outbreaks occur, we predict that we will be able to stop them after the first few cases, as we will rapidly find clear connections.”

In their next step, the team will study all MRSA carriers and infected patients over the next year in Addenbrooke‟s Hospital and surrounding hospitals and the community to understand transmission events with the aim of improving infection management.

Sir Mark Walport, Director of the Wellcome Trust, says: “This is a dramatic demonstration that medical genomics is no longer a technology of the future – it is a technology of the here and now. By collaborating with NHS doctors, geneticists have shown that sequencing can have extremely important applications in healthcare today, halting an outbreak of a potentially deadly disease.”

Article courtesy the Wellcome Trust Sanger Institute.

Orignation: University of Cambridge webpage

The new studies, sponsored by Genzyme (a Sanofi company) and Bayer Schering Pharma, showed that alemtuzumab significantly reduces the number of attacks (or relapses) experienced by people with MS compared to interferon beta-1a (known commercially as Rebif).  This was seen both in patients who had not previously received any treatment (drug-naïve) and those who have continued to show disease activity whilst taking an existing treatment for MS.

MRI showing lesions on the brain
Credit: Dr Alasdair Coles

In the CARE MSII trial, confined to patients who had recently relapsed on a licenced therapy, new episodes were reduced by 49 per cent more than that achieved by the current standard treatment for MS, interferon beta-1a.  Over a two year period, 65 per cent of patients on alemtuzumab compared to 47 per cent of patients on interferon remained relapse free. Additionally, alemtuzumab reduced the risk of acquiring disability by 42 per cent compared to interferon: disability worsened in 20% of interferon patients and 13% of alemtuzumab patients. Moreover, at the end of the study, on average, patients taking alemtuzumab had less disability than when they started the trial whereas those on interferon had experienced worsening disability.

“Our research shows the transformative effect that alemtuzumab can have for people with MS. Patients who continue to show disease activity while on their initial therapy are especially difficult to treat. Now, we have shown that alemtuzumab works where first-line drugs have already failed. It not only reduces the chances of disability associated with MS but may even result in long-term clinical improvements,” said Professor Alastair Compston from the University of Cambridge, principal investigator on both studies and Chair of the Steering Committee which oversaw these and earlier clinical trials.

For the study (CARE MS II), researchers recruited 840 MS patients (of whom 628 were used for the principal analysis) who had been treated previously but had recently relapsed during their therapy. They were divided in a ratio of 2:1 to receive either alemtuzumab or interferon beta-1a. Their disability was then assessed every three months for two years by a researcher who was not made aware of which drug the patient had received.  Additionally, they had annual scans to assess the lesions and brain shrinkage caused by MS.

Alemtuzumab was found significantly to reduce the risk of having another relapse of MS or becoming disabled over the next two years, compared to one of the most effective licensed therapies for similar cases of MS, interferon beta-1a. Additionally, most patients on alemtuzumab experienced an improvement in disability, which was not seen after treatment with interferon-beta 1a.  The brain scans showed that alemtuzumab not only reduced the number of new lesions, compared to interferon beta-1a, but also reduced the rate of brain shrinkage that occurs in MS as tissue is damaged.

“Although other MS drugs have emerged over the last year – which is certainly good news for patients – none has shown superior effects on disability when compared to interferon except alemtuzumab. Additionally, no other treatment has led to improvements in disability,” said Dr Alasdair Coles, lead author of the paper and a clinician from the University of Cambridge.

MS is an autoimmune disease in which the body’s immune system mistakenly attacks nerve fibres and their protective insulation, the myelin sheath, in the central nervous system. The resulting damage prevents the nerves from ‘firing’ properly and ultimately leads to the loss of the nerve fibre, resulting in physical and cognitive disabilities.

The results of a second phase III clinical trial (CARE MS I) also examined the effectiveness of alemtuzumab against the drug interferon beta-1a but in 581 drug-naïve patients.

It found that alemtuzumab reduced the number of attacks experienced by people with relapsing-remitting MS by 55 per cent over and above that achieved by interferon beta-1a.  Over a two year period, 78 per cent of patients on alemtuzumab compared to 59 per cent of patients on interferon remained relapse free.  The proportion of patients experiencing worsening of disability on this trial was slightly lower after alemtuzumab than interferon beta-1a, but this result was not statistically significant.

For both studies, the principal side-effect of treatment with alemtuzumab was the development of other autoimmune diseases.  During the trials, roughly 20 per cent of patients developed thyroid autoimmunity and 1 per cent developed an immune thrombocytopenia. Previous work has shown that up to 30 per cent of patients may develop autoimmune thyroid disease over time.

Laboratory work of the Cambridge research team, led by Dr Coles, is investigating how to detect people who are susceptible to these side-effects (funded by the Freemasons’ Grand Charity and the Multiple Sclerosis Society in the UK).  Additionally, they are currently recruiting for a trial of alemtuzumab in combination with a novel drug to reduce the risk of autoimmune diseases developing as a side-effect of taking alemtuzumab, funded by the Moulton Charitable Foundation and the Medical Research Council (MRC). Both Professor Alastair Compston and Dr Alasdair Coles are supported by the NIHR Biomedical Research Centre, Cambridge.

“Although alemtuzumab causes potentially serious side-effects, these can be identified and treated provided a monitoring schedule is carefully followed.  Additionally, we think that we can identify which patients are at risk of autoimmune disease after alemtuzumab, and we are currently recruiting for a clinical trial which will explore whether we can use a drug to reduce the risk of autoimmunity in those at highest risk,” said Dr Coles.

This brings to conclusion a unique programme for the development of a drug for MS that began in Cambridge in 1991. Never before has an MS drug been tested in clinical outcomes against such a high hurdle, an active first-line drug, in both one phase II trial and two phase III trials; and no drug for MS has been shown to be more effective, in both reducing the risk of disability and reducing the rate of brain atrophy, when compared to another active treatment.

Decisions on drug licences for alemtuzumab (known commercially as Lemtrada) by the European and US regulatory authorities are expected in 2013.

MS affects almost 100,000 people in the UK, 400,000 in the United States and several million worldwide.

This story first appeared on the University of Cambridge Research News website.