Alberto Severini - Academia.edu (original) (raw)

Papers by Alberto Severini

Advances in Preventive Medicine

Background. Population-specific epidemiologic data on human Papillomavirus infection, which are l... more Background. Population-specific epidemiologic data on human Papillomavirus infection, which are limited in most of the SubSaharan African countries, are necessary for effective cervical cancer prevention. This study aimed to generate population-specific data on human Papillomavirus infections, and determine which of these, self-collected and provider-collected specimens, gives a higher estimate of the prevalence of human Papillomaviruses, including vaccine and non-vaccine-type human Papillomavirus. Methods. In this cross-sectional study, following a questionnaire-based collection of epidemiological data, self-, and provider-collected specimens, obtained from women 15−65 years of age, were analysed for human Papillomavirus types by a nested-multiplex polymerase chain reaction, and for cervical lesions by Pap testing. HPV data were categorised according to risk type and vaccine types for further analysis. Results. The difference between the overall human Papillomavirus infection preva...

Canada Communicable Disease Report

Background: Measles molecular epidemiology was a key component of the verification of elimination... more Background: Measles molecular epidemiology was a key component of the verification of elimination of indigenous measles in Canada and is an invaluable tool during public health investigations, both to establish whether connections exist between concurrent measles cases and to indicate possible sources of importations. There are 24 distinct genotypes however the genotype is usually not sufficient to describe the complex molecular epidemiology of measles cases. The exact genetic sequence of the last 450 nucleotides of the nucleoprotein (N) gene (N-450) is used. The measles genome mutates very slowly and so cases within the same chain of transmission usually have identical N-450 sequences. In Canada, the National Microbiology Laboratory (NML) sequences the N-450 and deposits it into the WHO measles sequence database, MeaNS. This database can be used to identify other geographic regions where the measles sequence was detected, supporting or excluding connections. For commonly detected N-450 sequences, MeaNS designates a "sequence variant." Sequence variants are used as the defining characteristic of measles cases with identical sequences and this designation is fundamental to the description of measles molecular epidemiology both locally and globally. As progress is made towards global measles eradication, its genetic diversity decreases and distinct importations of measles from a single reservoir can be difficult to distinguish using current methods. Extending sequencing methods beyond the N-450 is required. While sequencing the entire hemagglutinin (H) gene, which is currently done routinely at the NML, can be helpful, whole genome sequencing will be required for effective molecular surveillance to monitor the sustained elimination of measles in Canada.insert text here.

Sexually transmitted diseases, Feb 1, 2017

We sought to confirm the results of 81 rectal specimens positive for Chlamydia trachomatis by the... more We sought to confirm the results of 81 rectal specimens positive for Chlamydia trachomatis by the APTIMA Combo 2 assay among patients with concurrently collected negative genitourinary specimens. A total of 79 (97.5%) samples were confirmed by the APTIMA single target assay and/or sequencing of the C. trachomatis ompA gene.

Emerging infectious diseases, 2017

The province of Ontario continues to experience measles virus transmissions despite the eliminati... more The province of Ontario continues to experience measles virus transmissions despite the elimination of measles in Canada. We describe an unusual outbreak of measles in Ontario, Canada, in early 2015 that involved cases with a unique strain of virus and no known association among primary case-patients. A total of 18 cases of measles were reported from 4 public health units during the outbreak period (January 25-March 23, 2015); none of these cases occurred in persons who had recently traveled. Despite enhancements to case-patient interview methods and epidemiologic analyses, a source patient was not identified. However, the molecular epidemiologic analysis, which included extended sequencing, strongly suggested that all cases derived from a single importation of measles virus genotype D4. The use of timely genotype sequencing, rigorous epidemiologic investigation, and a better understanding of the gaps in surveillance are needed to maintain Ontario's measles elimination status.

Virology journal, Apr 21, 2017

In addition to being useful for classification, sequence variations of human Papillomavirus (HPV)... more In addition to being useful for classification, sequence variations of human Papillomavirus (HPV) genotypes have been implicated in differential oncogenic potential and a differential association with the different histological forms of invasive cervical cancer. These associations have also been indicated for HPV genotype lineages and sub-lineages. In order to better understand the potential implications of lineage variation in the occurrence of cervical cancers in Ghana, we studied the lineages of the three most prevalent HPV genotypes among women with normal cytology as baseline to further studies. Of previously collected self- and health personnel-collected cervical specimen, 54, which were positive for HPV16, 18 and 45, were selected and the long control region (LCR) of each HPV genotype was separately amplified by a nested PCR. DNA sequences of 41 isolates obtained with the forward and reverse primers by Sanger sequencing were analysed. Nucleotide sequence variations of the HPV...

Infectious agents and cancer, 2017

HPV infections are ubiquitous and particularly common among sexually active young women. However,... more HPV infections are ubiquitous and particularly common among sexually active young women. However, there are regional and national variations in age-specific HPV prevalence, which have implications for cervical cancer control. Data on age-specific HPV prevalences for Ghana and most sub-Saharan countries are scanty. Therefore, this study primarily sought to determine the age-specific HPV prevalence among women in a Ghanaian community and to determine whether these prevalences determined with health-personnel and self-collected specimens were comparable. In this cross-sectional study, conducted between March 2012 and March 2013, cervical specimens were collected by self- and health-personnel collection from 251 women who were between the ages of 15 and 65 years. HPV present in these specimens were genotyped by a nested-multiplex PCR and Luminex fluoro-microspheres based method. Information on the demographic, sexual and reproductive characteristics of the women were also obtained. A Ch...

Journal of virological methods, 2017

Rapid and accurate detection of measles virus is important for case diagnosis and public health m... more Rapid and accurate detection of measles virus is important for case diagnosis and public health management. This study compared the performance of two monoplex RT-PCR reactions targeting the H and N genes to a duplex RT-PCR targeting both genes simultaneously. The duplex simplified processing without compromising assay performance characteristic.

Clinical and vaccine immunology : CVI, 2017

The BioPlex 2200 (Bio-Rad Laboratories, Hercules, CA) is a rapid, automated platform, which can s... more The BioPlex 2200 (Bio-Rad Laboratories, Hercules, CA) is a rapid, automated platform, which can screen large numbers of specimens for antibodies to measles, mumps, rubella, and varicella. Although approved for producing qualitative results, in this study we validated the test (off-label) to allow reporting of quantitative results. To do this, we used the third anti-measles World Health Organization standard to generate a calibration curve that allowed relative fluorescence intensity to be translated into quantitative antibody titer (antibody units [AU]/ml). The results from the BioPlex 2200 and the reference plaque reduction neutralization test (PRNT) exhibited a reasonable correlation following an exponential function, but correlation was poor in low-titer samples. Using a receiver operating characteristics analysis, an equivocal zone for the BioPlex 2200 was established between ≥0.13 and <1.10 AU/ml to achieve 100% specificity (95% confidence interval [CI] = 83.2 to 100%) and 1...

Journal of clinical microbiology, Jan 16, 2016

During measles outbreaks, it is important to be able to rapidly distinguish between measles cases... more During measles outbreaks, it is important to be able to rapidly distinguish between measles cases and vaccine reactions to avoid unnecessary outbreak response measures such as case isolation and contact investigations. We have developed a real-time RT-PCR method specific for genotype A measles virus (MeVA RT-qPCR), that can identify measles vaccine strains rapidly, with high throughput, and without the need for sequencing to determine the genotype. We have evaluated the method independently in three measles reference laboratories using two platforms, the Roche Lightcycler® 480 and the Applied Biosystems™ (ABI) 7500 Real-Time PCR System. In comparison to the standard real time RT-PCR method, the MeVA RT-qPCR showed 99.5% specificity for genotype A and 94% sensitivity for both platforms. The new assay was able to detect RNA from five currently used vaccine strains, AIK-C, CAM-70, Edmonston-Zagreb, Moraten, and Shanghai-191. The MeVA RT qPCR assay has been used successfully for measles...

BMJ Open, 2016

The incidence of cervical cancer is up to 20-fold higher among First Nations women in Canada than... more The incidence of cervical cancer is up to 20-fold higher among First Nations women in Canada than the general population, probably due to lower participation in screening. Offering human papillomavirus (HPV) self-sampling in place of Papanicolaou (Pap) testing may eventually increase screening participation and reduce cervical cancer rates in this population.

Health Reports Statistics Canada Canadian Centre For Health Information Rapports Sur La Sante Statistique Canada Centre Canadien D Information Sur La Sante, Apr 17, 2013

Background: Chlamydia, caused by Chlamydia trachomatis, and genital herpes, caused by simplex vir... more Background: Chlamydia, caused by Chlamydia trachomatis, and genital herpes, caused by simplex virus type 2 (HSV-2), are common sexually transmitted infections. Their prevalence has been estimated in selected populations, but overall prevalence in Canada is not known. Data and methods: Data are from the 2009 to 2011 Canadian Health Measures Survey. Socio-demographic, health and lifestyle information was obtained via a household questionnaire; blood and urine collected at a mobile examination centre were used to identify the presence of Chlamydia trachomatis and HSV-2 among 14- to 59-year-olds. Results: An estimated 13.6% of Canadians (2.9 million) tested positive for HSV-2, and another 0.7% (158,000), for chlamydia. HSV-2 affects higher percentages of women than men, and individuals aged 35 to 59 versus 15 to 34. No significant differences in HSV-2 prevalence were detected by marital status, household income, education, or racial background. Nearly all individuals with laboratory-confirmed chlamydia or HSV-2 were unaware that they were infected. Interpretation: This study is the first in Canada to report laboratory-confirmed prevalence of chlamydia and HSV-2 using a nationally representative sample. Results suggest that most infected people are unaware of their status.

Sexually Transmitted Diseases, Nov 1, 2010

Herpes simplex virus (HSV)-type specific serology (TSS) testing has been commercially available f... more Herpes simplex virus (HSV)-type specific serology (TSS) testing has been commercially available for nearly a decade. Guidelines on appropriate use of such testing exist, including Canadian-based recommendations. Despite this, most Canadian laboratories do not offer HSV-type specific serology and many provide only nontype-specific HSV serology tests. At the Alberta Provincial Laboratory, HSV TSS is performed using the following algorithm (termed the Alberta algorithm). Eligible specimens are first tested with a nontype-specific kit (Behring Enzygnost IgG). If positive, sera are then tested using the Focus HerpeSelect-2 assay to establish HSV-2 infection. If the HerpeSelect-2 result is negative, the result is reported as anti-HSV-1 positive. In this study we sought a validation of the Alberta algorithm by testing 344 serum samples with the Behring Enzygnost IgG assay, the type specific Focus HerpeSelect 1 and 2 assays, and by Western blot (WB). Taking the WB as a gold standard, the Behring Enzygnost IgG assay showed a sensitivity of 94% and a specificity of 100%, whereas the Alberta algorithm had a sensitivity of 92% and a specificity of 97% for the detection of HSV-2 antibodies, and a sensitivity of 94% and a specificity of 100% for the detection of HSV-1 antibodies in HSV-2 negative sera. Focus HerpeSelect 1 and HerpeSelect 2 sensitivities against WB were 88% and 91%, whereas specificities were 95% and 97% for HSV-1 and HSV-2, respectively. The Alberta algorithm was at least equivalent to HerpeSelect 1 and 2 in detecting anti-HSV antibodies. Although sensitivity and specificity were higher, the differences were not statistically significant.

Journal of Virology, 2015

ABSTRACTViruses utilize host cell machinery for propagation and manage to evade cellular host def... more ABSTRACTViruses utilize host cell machinery for propagation and manage to evade cellular host defense mechanisms in the process. Much remains unknown regarding how the host responds to viral infection. We recently performed global proteomic screens of mammalian reovirus TIL- and T3D-infected and herpesvirus (herpes simplex virus 1 [HSV-1])-infected HEK293 cells. The nonenveloped RNA reoviruses caused an upregulation, whereas the enveloped DNA HSV-1 caused a downregulation, of cellular secretogranin II (SCG2). SCG2, a member of the granin family that functions in hormonal peptide sorting into secretory vesicles, has not been linked to virus infections previously. We confirmed SCG2 upregulation and found SCG2 phosphorylation by 18 h postinfection (hpi) in reovirus-infected cells. We also found a decrease in the amount of reovirus secretion from SCG2 knockdown cells. Similar analyses of cells infected with HSV-1 showed an increase in the amount of secreted virus. Analysis of the stress...

Open forum infectious diseases, 2015

Background. In 1994, Canada committed to eliminate measles by the year 2000. This report present... more Background. In 1994, Canada committed to eliminate measles by the year 2000. This report presents the epidemiology of measles in Canada between 2002 and 2013 and its implications in sustaining measles elimination. Methods. Cases included individuals reported to the Canadian Measles and Rubella Surveillance System with confirmed measles. Results. In Canada, 1171 cases of measles were reported between 2002 and 2013 (incidence 0.29 cases per 100 000 population). The annual number of cases ranged from 6 to 752. The majority of cases were unvaccinated (63%) or had an unknown vaccination status (19%). The median age of cases was 14.4 years (range, <1 to 63 years) globally and 14 years when excluding the 2011 outbreak in Quebec where 68% of the 678 cases were 10 to 19 years old. With the exclusion of this outbreak, the incidence was highest in infants (1.0 per 100 000), lower but fairly similar between 1 and 19 years of age (0.2 to 0.4 per 100 000), and there was a substantial declin...

Health reports, 2010

With the recent introduction of a human papillomavirus (HPV) vaccine in Canada, it is important t... more With the recent introduction of a human papillomavirus (HPV) vaccine in Canada, it is important to establish surveillance and evaluation programs that not only track the uptake of the vaccine, but also assess its safety and its impact on: distribution of HPV type, cervical cancer screening programs, the incidence of anogenital warts, precancerous lesions and various cancers, and sexual behaviour. Administrative databases, registries and questionnaire information are being linked to identify people receiving the HPV vaccine and to develop an evaluation system. The availability of extensive linkable databases in Manitoba allows for the development of a comprehensive HPV vaccine surveillance and evaluation system that can address many of the questions related to the HPV vaccine. Aspects of the Manitoba surveillance and evaluation system could be implemented in other provinces that have similar databases.