Prevalence and diversity of rotavirus A genotypes cirulating in Turkey during a 2-year sentinel surveillance period, 2014-2016.

Human rotavirus A (RVA) is the main etiological agent of watery diarrhea among children under 5 years of age worldwide. The aims of this study were to investigate the prevalence and diversity of RVA genotypes circulating in Turkey during a 2-year sentinel surveillance study. A total of 1639 rotavirus antigen-positive stool samples were obtained from children younger than 5 years of age hospitalized with acute gastroenteritis. Rotavirus G and P genotypes were determined by reverse transcription polymerase chain reaction (RT-PCR) with consensus primers for the VP7 and VP4 genes, followed by semi-nested type-specific multiplex PCR. Rotavirus RNA was detected in 1396 (85.3%) of the samples tested. The highest detection rate (38.2%) was obtained among children in the 0-12 months age group, followed by children in the 13-24 months age group (36.2%). The most prevalent genotype was G1P[8] (24.6%) followed by G3P[8] (19.6%), G9P[8] (12.2%), G2P[4] (9.5%), G2P[8] (6.5%), and G4P[8] (4.8%). The proportions of uncommon and mixed genotypes were 21.5% and 1.14%, respectively. The large number of genotypes observed, including common, uncommon, and mixed types, indicates a high heterogeneity of RVA strains circulating in Turkey. The current study also exhibited dramatic fluctuations on the prevalences of the common genotypes, with increases in G3 and G1 and decreases in G9 and G2 from 2014-2016.

Towards measles elimination: Phylogenetic analysis of measles viruses in Turkey (2012-2013) and identification of genotype D8.

Molecular characterization of different measles virus (MV) strains is essential to combat the disease. Sixty measles MV strains were obtained from throat swabs or urine of patients in Turkey between 2012 and 2013 and characterized. MV RNA sequences (n = 60) were analysed for 456 nucleotides representing hypervariable domain of the nucleoprotein (N) gene. Of the 60 strains analysed 53 were the D8 genotype, 6 were B3, 1 was D4, and 1 was A. This report describes MV genotype D8 that was involved in a measles outbreak in Turkey. Sequences of most genotype D8 strains (n = 51) were identical to the sequence of variant D8-Frankfurt-Main, which has been associated with outbreaks throughout Europe. Despite the lack of epidemiologic information, a phylogenetic analysis suggested that the genotype D8 MV may have been brought to Turkey from elsewhere. Phylogenetic and epidemiological findings suggested that strains identified in tourists and associated with importation included one strain of genotype D8, one strain of genotype B3, and one strain of genotype D4. These findings from the 2012 to 2013 outbreak in Turkey confirm that pockets of unimmunised individuals are making the country susceptible to measles outbreaks. To prevent further outbreaks, deliberate and sustained effort must be made to reach, and immunise susceptible age groups. Towards measles elimination process, continued molecular surveillance of measles strains in Turkey will help identify transmission patterns of virus and evaluate vaccination efforts. J. Med. Virol. 88:1867-1873, 2016. © 2016 Wiley Periodicals, Inc.

Molecular characterization of measles viruses in Turkey (2010-2011): first report of genotype D9 involved in an outbreak in 2011.

Genetic characterization of measles viruses (MVs) combined with acquisition of epidemiologic information is essential for measles surveillance programs used in determining transmission pathways. This study describes the molecular characterization of 26 MV strains (3 from 2010, 23 from 2011) obtained from urine or throat swabs harvested from patients in Turkey. MV RNA samples (n = 26) were subjected to sequence analysis of 450 nucleotides comprising the most variable C-terminal region of the nucleoprotein (N) gene. Phylogenetic analysis revealed 20 strains from 2011 belonged to genotype D9, 3 to D4, 2 strains from 2010 to genotype D4 and 1 to genotype B3. This study represents the first report describing the involvement of MV genotype D9 in an outbreak in Turkey. The sequence of the majority of genotype D9 strains was identical to those identified in Russia, Malaysia, Japan, and the UK. Despite lack of sufficient epidemiologic information, the presence of variants observed following phylogenetic analysis suggested that exposure to genotype D9 might have occurred due to importation more than once. Phylogenetic analysis of five genotype D4 strains revealed the presence of four variants. Epidemiological information and phylogenetic analysis suggested that three genotype D4 strains and one genotype B3 strain were associated with importation. This study suggests the presence of pockets of unimmunized individuals making Turkey susceptible to outbreaks. Continuing molecular surveillance of measles strains in Turkey is essential as a means of acquiring epidemiologic information to define viral transmission patterns and determine the effectiveness of measles vaccination programs designed to eliminate this virus.

Monitoring genetic diversity of influenza A(H1N1)pdm09 virus circulating during the post-pandemic period in Turkey.

The aimes of the present study were to monitor genetic alterations in the hemagglutin (HA) gene and oseltamivir resistance-related alterations in the neuraminidase (NA) gene of influenza A(H1N1)pdm09 viral isolates detected during the post-pandemic period in Turkey. A total of 2601 clinical specimens obtained from suspected cases of influenza A(H1N1)pdm09 viral infections were analyzed by real-time reverse transcription polymerase chain reaction. Viral RNA was detected in 233 (9%) clinical specimens. Sequence analysis of the HA gene in 16 random isolates showed >98.7% homology among each other and with the A/California/07/2009 vaccine strain. These 16 isolates had common (75%-100%) amino acid substitiutions at positions P83S, D97N, S203T, R205K, I216V, V249L, I321V, and E374K in the HA gene. In addition, two additional rare mutations were also observed at positions S162N (addition of a glycosylation site, 6.25%) and A186T (receptor binding region, 6.25%). On the basis of amino acid substitutions in the HA1 domain, majority of the Turkish isolates were classified in the genetic group v and others in the genetic groups ii, iii, and vi. In the present study, we observed an increase in the variety and ratio of mutations detected in the HA1 and HA2 domains of the HA gene; however, these alterations have not yet resulted in vaccine escape mutants in Turkey. In addition, analysis of the NA regions of the isolates revealed that oseltamivir resistance was not an issue in Turkey.

The characterization of the neutralizing bovine viral diarrhea virus monoclonal antibodies and antigenic diversity of E2 glycoprotein.

Bovine viral diarrhea virus (BVDV) is associated with a range of economically important diseases of cattle including reproductive disorders and an acute fatal hemorrhagic disease. Neutralizing antibodies that bind to the E2 glycoprotein are important predictors of vaccinal immunity. Neutralization tests using the NADL strain of BVDV and five anti-E2 monoclonal antibodies showed one, Wb163, neutralized the NADL strain of BVDV in an unexpected manner. Its titer was 10,000 compared to <35 as reported previously. The present stock of NADL differed from that of the earlier study in that the amino acid at position 79 of E2 was Valine instead of Glutamic acid. MAb Wb163 may, however, recognize a less important neutralizing epitope than another mAb Wb166, because it was less cross reactive than mAb Wb166, had a neutralizing titer 50-fold lower than Wb166 and was of lower relative affinity than Wb166. Variations in the amino terminus of E2 will be discussed in the context of vaccinal immunity.

Lack of genetic diversity in Crimean-Congo hemorrhagic fever viruses in Turkey: assessment of present and future patterns of disease.

Crimean-Congo hemorrhagic fever (CCHF) is a tick-borne zoonosis which is common in Africa, Asia, Eastern Europe, and the Balkan Peninsula. CCHF has been reported in Turkey with high frequency since 2002. The aim of the present study was to investigate the genetic diversity and genetic relationship between CCHF virus (CCHFV) isolates derived from infected patients over a 2-year period (2009 and 2010) in several provinces of Turkey. Serum samples (n = 48) were selected from CCHFV RNA positive patients and subjected to sequence analysis of the gene regions encoding the S (48 samples) and M (14 samples) segments. The nucleotide sequence alignments showed that the nucleic acid relatedness of CCHFV isolates ranged from 95.7% to 100% and from 93.7% to 100% for S and M segments, respectively. Phylogenetic analysis of both segment sequences revealed that CCHFV isolates circulating in Turkey belonged to the European lineage I and were closely related to the viruses found in the Eastern European-Russian and Balkan Peninsula. The M gene segment-based phylogenetic analysis suggested that 2/14 CCHFV isolates (KYSR3159/09 and YZGT714/10) had additional genetic variations. The results of the present study confirmed that the CCHFV isolates present in Turkey associated with human disease had high genetic homology in S segment, but some variability in the M segment of the RNA.

Peptide mimics of hapten DNP: the effect of affinity of anti-DNP monoclonal antibodies for the selection of phage-displayed mimotopes.

Biopanning of two linear (6- and 15-mer) and two constrained (10- and 17-mer) phage-displayed peptide libraries with two anti-DNP monoclonal antibodies (mAbs) selected seven unique peptide sequences using only the low affinity anti-DNP monoclonal antibody. The selected peptides contained two of 6, one of 10, two of 15 and two of 17 amino acids in length. They were all rich in hydrophobic residues. Both 15-mer peptides had antigenic regions of eight amino acids as revealed by a spot scan assay. Two of the 17-mer and one of the 10-mer peptides displayed on phage competed with free DNP for the low affinity anti-DNP mAb. These findings highlight (i) the selective power of phage displayed peptide libraries to identify peptides that mimic the shape of a small hapten molecule such as DNP, (ii) the possible preferential bias of phage libraries towards low affinity antibodies, (iii) the importance of using a panel of phage libraries for selecting peptide mimics.

Selection of mimotopes of Bovine Viral Diarrhoea Virus using a solid-phase peptide library.

Bovine Viral Diarrhoea Virus (BVDV) is an important pathogen of cattle, causing important economical losses world-wide. In this study, an 8-mer solid-phase peptide library was screened with a neutralising monoclonal antibody 157 to generate mimotopes mimicking a conformational neutralising epitope of BVDV E2 protein. Two sequences selected 157A1 LFEQYYYF and 157A2 LYRFGEFD that did not show a high structural or sequence similarity with BVDV E2 glycoprotein reacted specifically with monoclonal antibody 157 when presented as solid-phase peptides in a SPOT scan assay. These results indicate that combinatorial peptide libraries can be used to identify potential mimotopes of conformational epitopes.