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Okomo-Adhiambo M.,Centers for Disease Control and Prevention | Okomo-Adhiambo M.,Collaborating Center for Surveillance | Hurt A.C.,Collaborating Center for Reference and Research on Influenza | Gubareva L.V.,Centers for Disease Control and Prevention | Gubareva L.V.,Collaborating Center for Surveillance
Methods in Molecular Biology | Year: 2012

Neuraminidase inhibitors (NAIs) represent a newer class of anti-influenza drugs. Widespread natural or acquired resistance to NAIs is a major public health concern as it limits pharmaceutical options available for managing seasonal and pandemic influenza virus infections. Molecular-based methods, such as pyrosequencing, sequencing, and PCR are rapid techniques for detecting known genetic markers of resistance, but they are unable to identify novel mutations that may confer resistance, or subtle differences in the susceptibility of viruses to the NAIs. This chapter describes the chemiluminescent neuraminidase (NA) inhibition (NI) assay, a functional method used for assessing influenza virus susceptibility to NAIs. The assay generates IC50 values (drug concentration needed to reduce the NA enzymatic activity by 50%) which are determined by curve-fitting analysis. Test viruses showing elevated IC 50 values relative to those of NAI-sensitive reference viruses of the same antigenic type and subtype are further analyzed by pyrosequencing or conventional sequencing to identify known markers of NAI resistance or new changes in the NA. The criteria for NAI resistance are currently not well defined and tend to vary by laboratory and NI assay, therefore harmonization of NI assay conditions and interpretation of results across surveillance laboratories is necessary to improve the NAI susceptibility testing and analysis. © 2012 Springer Science+Business Media, LLC.


Hurt A.C.,Collaborating Center for Reference and Research on Influenza | Okomo-Adhiambo M.,Centers for Disease Control and Prevention | Okomo-Adhiambo M.,Collaborating Center for Surveillance | Gubareva L.V.,Centers for Disease Control and Prevention | Gubareva L.V.,Collaborating Center for Surveillance
Methods in Molecular Biology | Year: 2012

Neuraminidase inhibitors (NAIs) are presently the only effective antiviral drugs for treatment and chemoprophylaxis of influenza A and B infections, due to the high prevalence of resistance to the adamantane class of drugs among influenza A(H3N2) and A(H1N1) viruses, including the 2009 pandemic H1N1 strain. The limited pharmaceutical options currently available for control of influenza infections underscore the critical need for surveillance on NAI susceptibility of influenza viruses circulating globally. This chapter describes the fluorescent neuraminidase (NA) inhibition (NI) assay, a functional method used for assessing influenza virus susceptibility to NAIs. The IC50 (drug concentration needed to reduce the NA enzymatic activity by 50%) values generated in this assay are used to evaluate the NAI-susceptibility of test viruses relative to those of sensitive reference viruses of the same antigenic type and subtype. Test viruses with significantly elevated IC50s are further analyzed by pyrosequencing or conventional sequencing to identify known markers of NAI resistance or novel changes in the NA. The harmonization of NI assay conditions and interpretation of results across surveillance laboratories is necessary to improve NAI susceptibility testing and analysis. © 2012 Springer Science+Business Media, LLC.


Barr I.G.,Collaborating Center for Reference and Research on Influenza | McCauley J.,Collaborating Center for Reference and Research on Influenza | Cox N.,Collaborating Center for Surveillance | Daniels R.,Collaborating Center for Reference and Research on Influenza | And 14 more authors.
Vaccine | Year: 2010

Influenza vaccines form an important component of the global response against infections and subsequent illness caused in man by influenza viruses. Twice a year, in February and September, the World Health Organisation through its Global Influenza Surveillance Network (GISN), recommends appropriate influenza viruses to be included in the seasonal influenza vaccine for the upcoming Northern and Southern Hemisphere winters. This recommendation is based on the latest data generated from many sources and the availability of viruses that are suitable for vaccine manufacture. This article gives a summary of the data and background to the recommendations for the 2009-2010 Northern Hemisphere influenza vaccine formulation. © 2009 Elsevier Ltd.


Yuan R.,Research Center for Pathogens Detection Technology of Emerging Infectious Diseases | Yuan R.,Collaborating Center for Surveillance | Yuan R.,South China Agricultural University | Wang Z.,Sun Yat Sen University | And 17 more authors.
Frontiers in Microbiology | Year: 2016

First identified in May 2014 in China's Sichuan Province, initial cases of H5N6 avian influenza virus (AIV) infection in humans raised great concerns about the virus's prevalence, origin, and development. To evaluate both AIV contamination in live poultry markets (LPMs) and the risk of AIV infection in humans, we have conducted surveillance of LPMs in Guangdong Province since 2013 as part of environmental sampling programs. With environmental samples associated with these LPMs, we performed genetic and phylogenetic analyses of 10 H5N6 AIVs isolated from different cities of Guangdong Province from different years. Results revealed that the H5N6 viruses were reassortants with hemagglutinin (HA) genes derived from clade 2.3.4.4 of H5-subtype AIV, yet neuraminidase (NA) genes derived from H6N6 AIV. Unlike the other seven H5N6 viruses isolated in first 7 months of 2014, all of which shared remarkable sequence similarity with the H5N1 AIV in all internal genes, the PB2 genes of GZ693, GZ670, and ZS558 more closely related to H6N6 AIV and the PB1 gene of GZ693 to the H3-subtype AIV. Phylogenetic analyses revealed that the environmental H5N6 AIV related closely to human H5N6 AIVs isolated in Guangdong. These results thus suggest that continued reassortment has enabled the emergence of a novel H5N6 virus in Guangdong, as well as highlight the potential risk of highly pathogenic H5N6 AIVs in the province. © 2016 Yuan, Wang, Kang, Wu, Zou, Liang, Song, Zhang, Ni, Lin and Ke.


Li B.,Southern Medical University | Li B.,Research Center for Pathogens Detection Technology of Emerging Infectious Diseases | Li B.,Collaborating Center for Surveillance | Chen R.,Southern Medical University | And 13 more authors.
Infection, Genetics and Evolution | Year: 2016

China's Guangdong Province is located along the same latitude as Kolkata, India and Dhaka, Bangladesh, and is also considered a source of epidemic cholera. However, molecular description and the genetic relationships between Vibrio cholerae O1 El Tor isolates in Guangdong remain unclear. In this study, 381 clinical V. cholerae O1 isolates recovered from cholera cases presenting in Guangdong between 1961 and 2013 were investigated by PCR, amplicon sequencing and pulsed-field gel electrophoresis (PFGE). During this time frame, four distinct epidemic periods (1-4) were observed based on the different dominant serotype leading its epidemic, correspond to years; or time periods from/to 1961-1969, 1978-1989, 1990-2000, 2001-2013, respectively. Molecular analysis of representative isolates indicated that a single dominating clone was associated with each epidemic stage. All isolates from periods 1 and 2 carried the typical El Tor ctxB; this allele was displaced by classical ctxB beginning in 1993. However all isolates carried the El Tor-specific toxin-coregulated pili subunit A (tcpA). Isolates were grouped into five clusters on the basis of Not I enzyme digested PFGE, and the first four clusters were associated with specific periods, cluster I (period 1), II (period 3), III (period 2) and IV (period 4), respectively. While cluster V consisted of isolates from all four epidemic periods, but was most heterogeneous in appearance. Our data indicate genetic variations that shape the relationship among emerging isolates of V. cholerae O1 in Guangdong Province contribute to the 7th global pandemic. © 2015.


LI B.S.,Research Center for Pathogens Detection Technology of Emerging Infectious Diseases | LI B.S.,Collaborating Center for Surveillance | XIAO Y.,Southern Medical University | WANG D.C.,Chinese National Institute for Communicable Disease Control and Prevention | And 11 more authors.
Epidemiology and Infection | Year: 2016

Vibrio cholerae O139 emerged as a causative agent of epidemic cholera in 1992 in India and Bangladesh, and was subsequently reported in China in 1993. The genetic relatedness and molecular characteristics of V. cholerae O139 in Guangdong Province, located in the southern coastal area of China, remains undetermined. In this study, we investigated 136 clinical V. cholerae O139 isolates from 1993 to 2013 in Guangdong. By conventional PCR, 123 (90·4%) isolates were positive for ctxB, ace and zot. Sequencing of the positive amplicons indicated 113 (91·7%) isolates possessed the El Tor allele of ctxB (genotype 3); seven carried the classical ctxB type (genotype 1) and three harboured a novel ctxB type (genotype 5). With respect to tcpA, 123 (90·4%) isolates were positive for the El Tor allele. In addition, pulsed-field gel electrophoresis (with NotI digestion) differentiated the isolates into clusters A and B. Cluster A contained seven of the non-toxigenic isolates from 1998 to 2000; another six non-toxigenic isolates (from 1998 and 2007) and all of the toxigenic isolates formed cluster B. Our results suggest that over a 20-year period, the predominant O139 clinical isolates have maintained a relatively tight clonal structure, although some genetic variance and shift has occurred. Our data highlight the persistence of toxigenic V. cholerae O139 in clinical settings in the southern coastal area of China. Copyright © Cambridge University Press 2016


Wu J.,Control Medical Technology | Wu J.,Collaborating Center for Surveillance | Yi L.,Guangdong Provincial Institute of Public Health | Zou L.,Control Medical Technology | And 13 more authors.
Eurosurveillance | Year: 2015

At the end of May 2015, an imported case of Middle East respiratory syndrome coronavirus (MERS-CoV) infection was confirmed in China. The patient is in a stable condition and is still undergoing treatment. In this report, we summarise the preliminary findings for this imported case and the results of contact tracing. We identified 78 close contacts and after 14 days of monitoring and isolation, none of the contacts presented symptoms and all tested negative for MERS-CoV. © 2015, European Centre for Disease Prevention and Control (ECDC). All rights reserved.


Stulhofer A.,University of Zagreb | Landripet I.,University of Zagreb | Bozic J.,University of Zagreb | Bozicevic I.,University of Zagreb | Bozicevic I.,Collaborating Center for Surveillance
AIDS Care - Psychological and Socio-Medical Aspects of AIDS/HIV | Year: 2015

Harm reduction-based HIV prevention has been in place among female sex workers (FSWs) in Croatia for more than a decade. However, little is known about how well the existing programs meet the needs of FSWs in an environment where sex work remains criminalized and highly stigmatized. This study aims to assess changes in FSWs' vulnerability to HIV infection in the 2008-2014 period. Using convenience samples of FSWs in Croatia's two largest urban settings, behavioral data were collected in 2007-2008 and 2014. Outreach workers interviewed 154 FSWs in the first wave of the survey and 158 in the second. The period under observation was characterized by a stable prevalence of most HIV-relevant risk behaviors and experiences. Significant changes in client-based victimization and HIV knowledge were observed only among FSWs in the capital city. Substantial and mostly sustained levels of sexual and nonsexual victimization call for more research into the limits of the current behavior-based harm reduction approach to HIV prevention in the country. © 2015 Taylor & Francis.

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