giovedì 28 agosto 2014

Genomic surveillance elucidates Ebola virus origin and transmission during the 2014 outbreak

In memory of the co-authors Mohamed Fullah, Mbalu Fonnie, Alex Moigboi, Alice Kovoma, and S. Humarr Khan, working at the Kenema Government Hospital, Kenema, Sierra Leone, who died from Ebola before the report got published in Science :

In its largest outbreak, Ebola virus disease is spreading through Guinea, Liberia, Sierra Leone, and Nigeria. We sequenced 99 Ebola virus genomes from 78 patients in Sierra Leone to ~2,000x coverage. We observed a rapid accumulation of interhost and intrahost genetic variation, allowing us to characterize patterns of viral transmission over the initial weeks of the epidemic. This West African variant likely diverged from Middle African lineages ~2004, crossed from Guinea to Sierra Leone in May 2014, and has exhibited sustained human-to-human transmission subsequently, with no evidence of additional zoonotic sources. Since many of the mutations alter protein sequences and other biologically meaningful targets, they should be monitored for impact on diagnostics, vaccines, and therapies critical to outbreak response (read more).

Robustness against serum neutralization of a poliovirus type 1 from a lethal epidemic of poliomyelitis in the Republic of Congo in 2010

In 2010, a large outbreak of poliomyelitis with unusual 47% lethality occurred in Pointe Noire, Republic of Congo. Vaccine-mediated immunity against the outbreak virus was never investigated. A wild poliovirus 1 (WPV1) isolated from a fatal case (termed PV1-RC2010) showed a previously unknown combination of amino acid exchanges in critical antigenic site 2 (AgS2, VP1 capsid protein positions 221SAAL→221PADL). These exchanges were also detected in an additional 11 WPV1 strains from fatal cases. PV1-RC2010 escaped neutralization by three different mAbs relevant for AgS2. Virus neutralization was tested in sera from fatal cases, who died before supplementary immunization (n = 24), Gabonese recipients of recent oral polio vaccination (n = 12), routinely vaccinated German medical students (n = 34), and German outpatients tested for antipoliovirus immunity (n = 17) on Vero, human rhabdomyosarcoma, and human epidermoid carcinoma 2 cells. Fatal poliomyelitis cases gave laboratory evidence of previous trivalent vaccination. Neutralizing antibody titers against PV1-RC2010 were significantly lower than those against the vaccine strain Sabin-1, two genetically distinct WPV1s isolated in 1965 and 2010 and two genetically distinct vaccine-derived PV strains. Of German vaccinees tested according to World Health Organization protocols, 15-29% were unprotected according to their neutralization titers (<1:8 serum dilution), even though all were protected against Sabin-1. Phylogenetic analysis of the WPV1 outbreak strains suggested a recent introduction of virus progenitors from Asia with formation of separate Angolan and Congolese lineages. Only the latter carried both critical AgS2 mutations. Antigenetically variant PVs may become relevant during the final phase of poliomyelitis eradication in populations with predominantly vaccine-derived immunity. Sustained vaccination coverage and clinical and environmental surveillance will be necessary (read more)

mercoledì 27 agosto 2014

Chikungunya Virus Transmission Found in the United States

It’s official: the chikungunya virus has arrived in the United States. Public health authorities confirmed the first 2 cases of local transmission in Florida about 6 weeks ago. This event was not unexpected, said health authorities. In December 2013, the World Health Organization reported the first local transmission of chikungunya virus in the Western Hemisphere, in the Caribbean. Within months, the disease spread through much of the Caribbean and Central and South America. As of late July, the Pan American Health Organization was reporting the number of suspected cases had topped 400 000 and was rapidly increasing. In French Saint Martin, where the virus first began spreading, an estimated 12% of the population has been infected, according to J. Erin Staples, MD, PhD, medical epidemiologist with the US Centers for Disease Control and Prevention (CDC) division of vector-borne diseases in Fort Collins, Colorado. Reflecting this spread, the number of US travelers who became infected with the virus during travel to the regions also has rapidly climbed (read more)

sabato 16 agosto 2014

RUO real-time PCR protocols without nucleic acid purification

for DNA viruses : AmpDirect (Shimadzu/Nacalai); HSV (ref), HBV (ref)

for RNA viruses : Cells-to-CT(TM) 1-Step Power SYBR(R) Green Kit (Life Technologies)

Since haemolysed, lipaemic and icteric serum samples from patients are inevitable in clinical practice, investigators should evaluate the interference of these endogenous substances (also known as the serum index), including conjugated bilirubin, haemoglobin and triglycerides, in real-time PCR.
Avoiding DNA extraction reduces risk of cross contamination, carryover and/or procedural error.

mercoledì 13 agosto 2014

Treatment of Hepatitis C A Systematic Review

Importance : Hepatitis C virus (HCV) infects more than 185 million individuals worldwide. Twenty percent of patients chronically infected with HCV progress to cirrhosis. New, simpler therapeutics using direct-acting antivirals that target various stages of the HCV life cycle are in development to eradicate HCV without concomitant interferon.
Objectives : To summarize published evidence on safety, efficacy (measured by a sustained virologic response [SVR], which is the treatment goal of undetectable plasma HCV RNA 12 or 24 weeks after therapy completion), and tolerability of current US Food and Drug Administration–approved interferon-based regimens and oral interferon-free regimens used for treating HCV infection and coinfection with human immunodeficiency virus (HIV) and HCV; to provide treatment recommendations for specialists and generalists based on published evidence.
Evidence Review : A literature search of Web of Science, Scopus, Embase, Agricola, Cochrane Library, Cinahl Plus,, Conference Papers Index, Gideon, PsycINFO, Google Scholar, and Oaister was conducted from January 1, 2009, to May 30, 2014. Publications describing phase 2, 3, and 4 studies evaluating the treatment of HCV were included. Forty-one studies involving 19 063 adult patients were included. Strength of clinical data and subsequent HCV treatment recommendations were graded according to the Oxford Centre for Evidence-Based Medicine.
Findings : Patients infected with HCV genotype 1 represent 60% to 75% of HCV infections in the United States. Hepatitis C virus genotype 1 is more difficult to cure than genotype 2 or genotype 3. Patients with HCV genotype 1 should receive treatment with sofosbuvir + pegylated interferon + ribavirin because of the shorter duration of therapy and high rates of SVR (89%-90%). Simeprevir + pegylated interferon + ribavirin is an alternative for patients with HCV genotype 1 (SVR, 79%-86%). Patients with HCV genotypes 2 and 3, representing 20% to 29% of US HCV infections, should receive therapy with sofosbuvir + ribavirin alone (SVR for genotype 2, 12 weeks’ duration: 82%-93%; SVR for genotype 3, 24 weeks’ duration, 80%-95%). Patients with HIV-HCV coinfection and patients with compensated cirrhosis (ie, cirrhosis but preserved synthetic liver function) should receive the same treatment as HCV-monoinfected patients.
Conclusions and Relevance : New, short-duration, simpler therapies result in high SVR rates for HCV-infected patients. In conjunction with increased screening for HCV as suggested by recent Centers for Disease Control and Prevention guidelines, availability of new therapies may lead to the treatment of many more people with chronic HCV infection (read more)