Nada M. Melhem

Primary Human Immunodeficiency Virus Type 1-Specific CD8+ T-Cell Responses Induced by Myeloid Dendritic Cells

ABSTRACT Induction of an antigenically broad and vigorous primary T-cell immune response by myeloid dendritic cells (DC) in blood and tissues could be important for an effective prophylactic or therapeutic vaccine to human immunodeficiency virus type 1 (HIV-1). Here we show that a primary CD8+ T-cell response can be induced by HIV-1 peptide-loaded DC derived from blood monocytes of HIV-1-negative adults and neonates (moDC) and by Langerhans cells (LC) and interstitial, dermal-intestinal DC (idDC) derived from CD34+ stem cells of neonatal cord blood. Optimal priming of single-cell gamma interferon (IFN-γ) production by CD8+ T cells required CD4+ T cells and was broadly directed to multiple regions of Gag, Env, and Nef that corresponded to known and predicted major histocompatibility complex class I epitopes. Polyfunctional CD8+ T-cell responses, defined as single-cell production of more than one cytokine (IFN-γ, interleukin 2, or tumor necrosis factor alpha), chemokine (macrophage inhibitory factor 1β), or cytotoxic degranulation marker CD107a, were primed by moDC, LC, and idDC to HIV-1 Gag and reverse transcriptase epitopes, as well as to Epstein-Barr virus and influenza A virus epitopes. Thus, three major types of blood and tissue myeloid DC targeted by HIV-1, i.e., moDC, LC, and idDC, can prime multispecific, polyfunctional CD8+ T-cell responses to HIV-1 and other viral antigens.

Hepatitis A virus in the Middle East and North Africa region: a new challenge.

During the past three decades, a gradual shift in the age of infection with hepatitis A virus (HAV) from early childhood to adulthood has been observed. There is a general lack of updated data on HAV burden of disease, incidence and age‐specific seroprevalence in countries of the Middle East and North Africa (MENA) region. The aim of this article is to review the published data on anti‐HAV seroprevalence, an important tool to monitor infections rates, in countries of the MENA region and associated risk factors including water and socioeconomic data when available. Data on anti‐HAV seroprevalence were found for 12 of 25 MENA countries. We show that MENA countries, similar to other areas in the world, have a clear shift in HAV incidence with a decline among young age groups and an increase among adults and older individuals. This would likely be associated with increased morbidity and increased risks of outbreaks among younger age groups. Consequently, the continuous surveillance of hepatitis A cases and the inclusion of hepatitis A vaccine in the expanded immunization programmes are needed in countries of the MENA.

Hepatitis C virus infection in the Middle East and North Africa "MENA" region: injecting drug users (IDUs) is an under-investigated population.

PurposeInvestigation of the injecting drug users (IDUs) population is becoming extremely critical and timely in light of the recent evidence that IDUs now act as the core of hepatitis C virus (HCV) epidemics in developed countries. The purpose of this article, therefore, is not only to review the epidemiology of HCV in the Middle East and North Africa (MENA) region, but also to see whether IDUs were adequately studied and whether harm reduction strategies to be applied for their protection have been set.MethodsA literature review was carried out of articles published within the last decade on HCV infection.ResultsThe gathered data showed that the population of IDUs is severely under-investigated throughout the whole region, possibly due to religious and cultural impediments.ConclusionIn order to reduce the risk of HCV infection in IDUs, a set of recommendations are advanced emphasizing the urgent need for bio-behavioral studies in this population in order to help identify the source and mode of transmission and the genotypes of HCV involved. These results may allow the development of effective and, yet, socially acceptable intervention strategies. We believe that the role which IDUs play in sustaining HCV infection is also an under-investigated topic in many developing countries. Similar reviews and, hence, interventions should be initiated in these regions.

The changing pattern of hepatitis A in Lebanese adults

OBJECTIVE A shift in the age of hepatitis A virus (HAV) infection from early childhood to adulthood has been observed in many developing countries. This epidemiological shift has been attributed to improved socioeconomic status and sanitary conditions resulting in growing cohorts of susceptible young people and hence an increased risk of HAV outbreaks. The aim of this study was to investigate the evolutionary trend of anti-HAV seroprevalence in Lebanon in a cohort of Lebanese adults. METHODS This was a cross-sectional study employing a convenience sample (voluntary blood donors) along with secondary data analysis. Sera from 283 healthy blood donors were tested for anti-HAV IgG antibodies. Moreover, we analyzed the national reports of HAV cases published by the Lebanese Ministry of Public Health since 2001. RESULTS Anti-HAV seropositivity increased steadily from 60% in the younger age group (19-29 years) to 91% in the older age group (50-59 years), leaving the younger group at higher risk of acquiring HAV. The national data show that the number of acute hepatitis A infections is higher in the age groups 5-9 and 10-19 years. CONCLUSION Our seroprevalence data reveal that young adults are becoming more at risk of acquiring HAV infection. Thus the introduction of hepatitis A vaccine is highly recommended.

The impact of viral evolution and frequency of variant epitopes on primary and memory human immunodeficiency virus type 1-specific CD8+ T cell responses

It is unclear if HIV-1 variants lose the ability to prime naïve CD8(+) cytotoxic T lymphocytes (CTL) during progressive, untreated infection. We conducted a comprehensive longitudinal analysis of viral evolution and its impact on primary and memory CD8(+) T cell responses pre-seroconversion (SC), post-SC, and during combination antiretroviral therapy (cART). Memory T cell responses targeting autologous virus variants reached a nadir by 8 years post-SC with development of AIDS, followed by a transient enhancement of anti-HIV-1 CTL responses upon initiation of cART. We show broad and high magnitude primary T cell responses to late variants in pre-SC T cells, comparable to primary anti-HIV-1 responses induced in T cells from uninfected persons. Despite evolutionary changes, CD8(+) T cells could still be primed to HIV-1 variants. Hence, vaccination against late, mutated epitopes could be successful in enhancing primary reactivity of T cells for control of the residual reservoir of HIV-1 during cART.

Characterization of astrovirus-associated gastroenteritis in hospitalized children under five years of age

PURPOSE The aim of this study was to determine the incidence and genetic diversity of astrovirus (AstV) detected in children hospitalized for gastroenteritis (GE). METHODS A multi-center, hospital-based surveillance study was conducted across Lebanon to investigate the incidence of AstV among diarrheal hospitalizations. Viral RNA was extracted from stool samples collected between 2011 and 2013 from children, below the age of 5years, hospitalized for GE at six medical centers across Lebanon. Demographic and clinical data were collected and analyzed. RNA of eligible samples (n=739) was screened by two AstV-specific PCR assays followed by genotype-specific PCR. Sanger sequencing and phylogenetic analysis were performed for genotypic characterization. RESULTS Overall, 5.5% (41/739) of rotavirus-negative stool samples collected from hospitalized children <5years old tested positive for AstV infection. AstV infections were detected all year long. Diarrhea, dehydration, vomiting and fever were the most common symptoms associated with AstV infections. Children aged 48-59months had the highest incidence of AstV. Using the Vesikari Scoring System to assess clinical severity, 85.4% of children with AstV had a score>11, indicating severe GE. Genotype-specific PCR identified 22 classical and 4 MLB-like AstV specimens. Further sequencing and phylogenetic analysis of orf1b and orf2 genes revealed that AstV classical 1-3, 5, 6, and 8, MLB-1, VA-1 and -2 genotypes circulated in Lebanon. Recombination between classical AstV strains was detected in several cases as evident by the lack of congruency in the tree topologies of the orf1b and orf2. Two cases of mixed infections between classical and non-classical genotypic strains were recorded. CONCLUSION High genetic diversity was detected among AstVs in Lebanon. AstVs are associated with 5.5% of non-rotavirus GE-associated hospitalizations in children under five years in Lebanon.

The Syrian refugees crisis brings challenges to the health authorities in Europe: hepatitis A virus is a case in point

The ongoing 3-year Syrian Civil war has left hundreds of thousands killed or wounded in addition to the displacement of more than 6.5 million Syrians throughout the world [1]. According to the United Nations High Commission on Refugees (UNHCR), the bulk of those displaced are hosted by neighboring countries: Lebanon (approximately 1.2 million people), Jordan (approximately 650,000), Iraq (approximately 250,000) and Turkey (approximately 1.9 million) [1]. It has been reported that slightly more than 10 % of the displaced Syrian refugees are seeking safety in Europe. The majority of the Syrian refugees in Europe are concentrated in Serbia and Germany (57 %) compared to 31 % in Sweden, Hungary, Austria, Netherlands and Bulgaria, and 12 % in the remaining 37 European Countries [2]. These numbers are increasing daily along with the associated challenge of their adequate settlement [3]. The influx of refugees to Europe presents the health authorities with the potential of introducing infectious diseases that have had low rates of morbidity and mortality in the hosting countries across time. These diseases include measles, polio, hepatitis A virus (HAV), hepatitis B virus (HBV), tuberculosis, human immunodeficiency virus (HIV), hepatitis C virus (HCV), cutaneous leishmaniasis, schistosomiasis, MERS-CoV, Haemophilus influenzae type b (Hib), as well as many vaccine-preventable diseases (DTap, meningococcal, varicella) that have been reported to be on the rise among Syrian refugees in Lebanon, Turkey, Jordan and Iraq [4–7]. The breakdown in the Syrian health care infrastructure led to the discontinuation of vaccination programs in the country. The disruption of vaccination in addition to over crowdedness, the miserable living condition and the lack of basic health care facilities culminated in severe outbreaks of vaccine-preventable diseases such as polio [8] and measles [9] in refugee camps in Syria and neighboring countries [10]. While most of the European populations are immunized against vaccine-preventable diseases, an imminent challenge is introduced due to the Syrian settlement in Europe especially due to the lack of implementation of vaccination against expected re-emerging infections; hepatitis A virus infection is a case in point. HAV, a non-enveloped RNA virus belonging to the family picornaviridae, continues to cause significant morbidity in many parts of the world [11]. Recent estimates indicate a global incidence of 1.9 % with 119 million cases infected with HAV [12]. HAV virus is primarily transmitted via ingestion of contaminated food or water or through direct contact with an infected person. The severity of HAV infection increases with age [12]. The overwhelming majority of children \5 years of age show no sign of infection (asymptomatic) compared to more than 70 % of cases in older children and adults presenting with jaundice. Consequently, the proportion of cases requiring hospitalization increases with age ranging from 21 % in children\5 years to 53 % among adults aged C60 years [13]. The endemicity of HAV is ranked as high, intermediate or low in different geographic areas. The level of endemicity correlates with sanitary and hygienic conditions [14]. Consequently, the incidence of hepatitis A infection is strongly correlated with access to safe drinking water, to & Sami Ramia sramia@aub.edu.lb

Norovirus vaccines: Correlates of protection, challenges and limitations

ABSTRACT Norovirus (NoV) is responsible for at least 50% of all gastroenteritis outbreaks worldwide. NoVs are classified into 6 different genogroups (GGI- GGVI) based on the viral capsid protein with NoV genogroup II genotype 4 (GII.4) being the predominant strain causing human diseases. Supportive therapy involving reversal of dehydration and electrolyte deficiency is the main treatment of NoV gastroenteritis. However, the worldwide increased recognition of NoV as an important agent of diarrheal gastroenteritis prompted researchers to focus on establishing preventive strategies conferring long-lasting immunity. This review describes the current status of animal and human vaccine models/studies targeting NoV and addresses the factors hampering the development of a broadly effective vaccine.

Update on the epidemiology of rotavirus in the Middle East and North Africa

Rotavirus (RV) is the leading cause of severe acute gastroenteritis (AGE) worldwide. Consequently, we conducted a systematic literature review on articles studying RV in the 25 countries of the MENA region during the past 15years (2000-2015). The methods and reporting were set according to the 2015 preferred reporting items for systematic review and meta-analysis protocols (PRISMA-P) and based on the elements from the international prospective register of systematic reviews (PROSPERO). Our literature search identified 169 studies meeting our predefined inclusion criteria. Studies reporting on RV were conducted in 19 out of the 24 countries of the MENA region. The largest number of studies was reported in Turkey (n=32), Iran (n=31), Saudi Arabia (n=19) and Egypt (n=17). The majority of studies reporting on RV gastroenteritis rates were clinical observational studies. In 115 studies out of 169, RV was reported among in-patients whereas 35 studies reported RV among outpatients. The predominantly reported RV genotype in the region was G1[P8] followed by G2[P4] and G9[P8]. The majority of studies (n=108) were conducted among children less than 5years of age whereas the remaining studies reported on AGE among other age groups and rarely adults. In MENA countries, RV infection was reported all year round with peaks described in cold as well as hot months. This systematic review provides a current update on the epidemiology of RV-associated gastroenteritis in countries of the MENA region and draws attention to the major gaps existing in the continuous monitoring of RV.

Clinical and epidemiological characteristics of norovirus gastroenteritis among hospitalized children in Lebanon

AIM To assess the burden of norovirus (NoV) and to determine the diversity of circulating strains among hospitalized children in Lebanon. METHODS Stool samples were collected from children presenting with acute gastroenteritis to six major hospitals in Lebanon. A total of 739 eligible stool samples, testing negative for diarrhea caused by rotavirus as a possible viral pathogen, were collected between January 2011 and June 2013. A standardized questionnaire including demographic, epidemiological and clinical observations was used at the time of hospitalization of children presenting with diarrhea. Viral RNA was extracted from stool samples followed by reverse transcription polymerase chain reaction and nucleotide sequencing of a fragment of the viral protein 1 capsid gene. Multiple sequence alignments were carried out and phylogenetic trees were constructed using the MEGA 6 software. RESULTS Overall, 11.2% of stool samples collected from children aged < 5 years tested positive for NoV genogroups I (GI) and II (GII). GII accounted for 10.6% of the gastroenteritis cases with only five samples being positive for GI (0.7%). The majority of hospitalized children showed symptoms of diarrhea, dehydration, vomiting and fever. Upon sequencing of positive samples and based on their clustering in the phylogenetic tree, 4/5 of GI gastroenteritis cases were designated GI.3 and one case as GI.4. GII.4 was predominantly detected in stool of our study participants (68%). We report a JB-15/KOR/2008 GII.4 Apeldoorn 2008-like variant strain circulating in 2011; this strain was replaced between 2012 and 2013 by a variant sharing homology with the Sydney/NSW0514/2012/AUS GII.4 Sydney 2012 and Sydney 2012/FRA GII.4 strains. We also report the co-circulation of non-GII.4 genotypes among hospitalized children. Our data show that NoV gastroenteritis can occur throughout the year with the highest number of cases detected during the hot months. CONCLUSION The majority of NoV-associated viral gastroenteritis cases among our participants are attributable to GII.4, which is compatible with results reported worldwide.