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Influenza surveillance provides data about the characteristics of influenza activity, types, sub-types and antigenic properties of the influenza viruses in circulation in a region. Surveillance also provides for the preparation against potential influenza pandemics with the identification of the genetic properties of viruses and the mutant strains that could pose a threat. In this study, data in the scope of national influenza surveillance carried out by National Influenza Center, Turkey for five consecutive influenza seasons between 2010-2015, following the A(H1N1)pdm09 virus pandemic, have been presented and evaluated. A total of 15.149 respiratory samples, including 8.894 sentinel and 6.255 non-sentinel specimens, during 2010-2015 influenza seasons, within the periods between September and May, were evaluated in our center. All samples were tested using real-time reverse transcriptase PCR (rRT-PCR) for the presence of influenza virus types and subtypes. Within the sentinel influenza surveillance, the samples that were detected negative for influenza viruses, have also been tested for the other respiratory viruses (respiratory syncytial virus, rhinoviruses, paramyxoviruses, coronaviruses) using the same technique. Further analysis, including virus isolation by cell culture inoculation and antigenic characterization by hemagglutination inhibiton test were performed for the samples found positive for influenza A and B viruses. Selected representative virus isolates have been sent to WHO reference laboratory for the sequence analysis. In the study, influenza virus positivity rates detected for all of the samples (sentinel+non-sentinel) were as follows; 34% (779/2316) in 2010-11 season; 25% (388/1554) in 2011-12; 20% (696/3541) in 2012-13; 23% (615/2678) in 2013-14; and 26% (1332/5060) in 2014-15. When all the samples were considered for influenza A and B viruses, the positivity rates for the seasons of 2010-11; 2011-12; 2012-13; 2013-14; 2014-15 were determined as follows; 49.9% and 50.1%, 71.6% and 28.4%; 98.3% and 1.7%; 73.6% and 26.4%; 48.1% and 51.9%, respectively. The frequency of respiratory viruses detected only in sentinel samples other than influenza, were found as follows; 10% (148/1435) in 2010-11; 18% (175/963) in 2011-12; 23% (415/1768) in 2012-13; 22% (468/2108) in 2013-14; and 21% (546/2620) in 2014-15 seasons. When the distribution of influenza virus subtypes were considered, the detection rates of A(H1N1)pdm09 and A(H3N2) viruses in all of the samples were 55% and 45%; 0% and 100%; 95% and 5%; 2% and 98%; and 79% and 21% in the seasons of 2010-11; 2011-12; 2012-13; 2013-14; and 2014-15, respectively. For B/Victoria and B/Yamagata lineages, those rates in the same order of seasons were found as 15% and 85%; 98% and 2%; 0% and 100%; 16% and 84%; and 2% and 98%, respectively. When the data were evaluated, for 2010-2011 and 2014-2015 seasons, cocirculation of influenza A and B were observed within the same periods and similar proportions, but the peak activity occurred 7-8 weeks later for 2014-2015 season. For both seasons, A(H1N1)pdm09 viruses were predominant for non-sentinel, while A(H3N2) viruses were predominant for sentinel detections. During 2011-2012 and 2013-2014 seasons, influenza activity presented similar profile; predominance of A(H3N2) and B viruses observed while A(H1N1)pdm09 virus detections remained low. In contrast, for the 2012-2013 season, A(H1N1)pdm09 viruses were predominant and the detection of A(H3N2) and B viruses remained low. For the seasons in which A(H3N2) was predominant, the peak activity seen earlier than the other seasons. For all seasons, A(H1N1)pdm09 viruses in circulation were antigenically compatible with the vaccine virus, while A(H3N2) viruses were compatible for three seasons (2010-11, 2012-13, 2013-14) and incompatible in two seasons (2011-12, 2014-15). Influenza B viruses were determined as antigenically compatible with the vaccine viruses in all except 2010-2011 season. Predominance of B/Victoria lineage were observed during 2011-2012 season while the rest of the majority were B/Yamagata. The positivity rates of other respiratory viruses which were also analyzed in the scope of sentinel influenza surveillance were similar to influenza positivity for all seasons except 2010-2011. This fact has emphasized that, those viruses were also responsible for influenza-like illness especially during the early and late phases of the season. In conclusion, monitoring of the antigenic and genetic characteristics of influenza viruses by surveillance studies is essential for the early detection of potential pandemic variants as well as to ensure similarities among the circulating strains and the corresponding vaccine strains.

Although adenoviruses (AdVs) generally cause upper respiratory tract infections, conjunctivitis/epidemic keratoconjunctivitis, gastroenteritis and pneumonia, they can lead to the involvement of central nervous system. Acute flaccid paralysis (AFP) is a type of seizure, characterized by rapid and sudden onset of extreme weakness in hands and feet, including (less frequently) weakness of respiratory and swallowing, representing with decreased muscle tone, especially in children below 15-year-old. The major viral cause of AFP is polioviruses, however non-polio enteroviruses, mumps virus, rabies virus and flaviviruses can also be responsible for AFP. The data of some recent studies have pointed out the probable aetiological role of AdVs in AFP. The aim of this study was to investigate the frequency of AdVs from stool samples of AFP-suspected patients and their contacts. A total of 6130 stool samples from patients (age range: 0-15 years) prediagnosed as AFP (n= 3185) and their contacts (n= 2945), which were sent to our laboratory from the health care centers located at different regions of Turkey for the monitorization of poliomyelitis as part of national AFP surveillance programme, between 2000-2014, have been retrospectively evaluated in terms of adenovirus isolation frequency. Samples were analyzed according to the algorithm recommended by World Health Organization and inoculated in Hep-2, RD, and L20B cell lines for cultivation. Apart from enteroviruses, in case of the presence of characteristic cytopathic effects for AdVs observed in L20B cells were confirmed by a commercial Adeno agglutination kit (Diarlex Adeno; Orion Diagnostica, Finland). It was noted that AdVs have been isolated from 1.6% (97/6130) of the samples, and out of positive samples 76.3% (74/97) were from AFP-suspected cases, while 23.7% (23/97) were from their contacts. Accordingly the frequencies of AdVs from AFP-suspected cases and their contacts were found as 2.3% (74/3185) and 0.8% (23/2945), respectively. The frequencies of Adenovirus positivity between the patients and their contacts were statistically significant (Z-Score 4.8347; p< 0.05). It was determined that 52.6% of the detected AdVs among AFP-suspected cases were between 1-4 age group and the positivity was 1.6 times more among males than the females. Although the data of this study are in agreement with the studies that support the relationship of AdVs with AFP, it is obvious that further molecular and clinical studies are needed.

Human metapneumovirus (HMPV), classified in Paramyxoviridae family, phylogenetically consists of two major groups namely A and B, with genetic lineages of A1, A2 (comprises of sublineages A2a and A2b) and B1, B2. Although detailed evaluation on phylogenetic analysis of HMPV has been described in other countries, there are no data from Turkey on this subject. The aim of this study was to demonstrate for the first time, the phylogenetic diversity of HMPV strains circulating in Turkey during two consecutive epidemic seasons. A total of 2900 upper respiratory tract samples collected from patients with respiratory illness were evaluated between January 2011 and December 2013, without any special selection criteria. The presence of respiratory viruses in the samples were detected by real-time multiplex polymerase chain reaction (FTD® Respiratory Pathogens 21 Multiplex RT-PCR, Fast Track Diagnostics, Luxemburg), and 76 (2.6%) samples positive for HMPV were included in the study. HPMV nucleocapsid (N) (nt: 454-878) and fusion (F) (nt: 3624-4130) genes were selected for phylogenetic analysis. In sequence analysis, F and N gene sequences could only be obtained successfully from 46 out of 76 HMPV positive samples. According to sequences obtained, 54.3% belonged to B2, 17.4% to B1, 4.3% to A1, 4.3% to A2a, and 20% to A2b. In 2011, the A2b sublineage was predominant, while in 2012 and 2013, B2 lineages were predominant together with the B1 lineage. The A1 lineage was observed only in 2013. For the F gene fragment, nucleotide distance between group A and B was in the range of 0.138-0.168, however aminoacid distance amongst Turkish HMPV sequences were in the range of 0.028-0.042. For the N gene fragment, nucleotide distance between group A and B was in the range of 0.141-0.163, but aminoacid distance between group A and B was in the range of 0.037-0.050. Nucleotide diversity was higher than aminoacid diversity between and within lineages found in this study. This result indicated that the functional constraints on F and N genes prevent dramatic aminoacid changes, and indicated that the evolution of HMPV was slow. The seasonal peaks were observed from April to July in 2011, from January to June in 2012 and from January to May in 2013. In addition, our data emphasized that the HMPV prevalence was high in children 0-5 years old, and coinfections were common with the other respiratory viruses such as respiratory syncytial virus, coronavirus, parainfluenza virus 3, rhinovirus and enterovirus. In conclusion, this study showed that HMPV strains circulating in Turkey were similar to those circulating in Europe.

Coronaviruses (CoV) are enveloped, spherical, single-stranded positive-sense RNA viruses causing mainly respiratory and intestinal infections in animals and humans. Until recently five types of human coronaviruses (HCoV-OC43, HCoV-HKU1, HCoV-NL63, HCoV-229E, SARS-CoV) have been known, however a novel CoV has been identified in 2012 in Saudi Arabia. This virus, namely MERS-CoV (Middle East Respiratory Syndrome Coronavirus), was classified within Coronaviridae family, Coronavirinae sub-family, Betacoronavirus genus, clade C. It causes acute respiratory infections in humans and transmits via respiratory route and close contact between humans. The aim of this study was to present the first MERS case from Turkey identified by molecular methods and the results of viral sequence analysis. A 42-year-old male Turkish citizen who worked as an employee in Jeddah, Kingdom of Saudi Arabia, admitted to hospital with the complaints of fever and malaise on 25-26 September 2014. Since his symptoms went on and got worse, he returned to Turkey, and hospitalized in a hospital's intensive care unit in Hatay on 6th of October with the symptoms of fever, malaise, sweating, cough and respiratory distress. He transferred to a university hospital on 8th of October and died on 11th October. The tracheal aspirate sample obtained before he died was sent to Virology Unit of Reference Laboratories of the Turkish Public Health Institution. Detection of viral RNA was performed by using a commercial real-time PCR kit (hCoV-EMC Real-Time RT-PCR, Fast Track Diagnostics, Luxembourg) targeting the MERS-CoV E protein (upE), ORF1a and ORF1b gene regions. The reference method Superscript III One Step RT-PCR (Invitrogen, USA) recommended by World Health Organization (WHO) was also applied for confirmation. Both of the methods yielded positive results for MERS-CoV RNA. For the amplification of nucleocapsid (N) and RNA-dependent RNA polymerase (RdRp) genes, hemi-nested PCR (Invitrogen, ABD) was conducted, followed by sequence analysis of 204 nucleotide part of N gene. Phylogenetic tree of N gene was obtained with the use of MEGA6 software. N gene was chosen as it comprised a two aminoacid deletion in the corresponding published sequence from the patient treated in London, United Kingdom. There was no nucleotide or aminoacid change in our isolate, namely ANK/1079/2014 when compared with human Betacoronavirus 2c EMC/2012 reference strain found in Genbank database. The target gene regions selected in our study (UpE, ORF1a, ORF1b, N and RdRp) which were also recommended by WHO, shown to have high specificity and sensitivity for the diagnosis and confirmation of MERS-CoV, and also recommended by WHO. The previous studies indicated that, the viral genomes detected in the earliest cases of humans (clade A) are genetically distinct from the others (clade B) which were isolated from dromedary camels and humans. In our study, according to phylogenetic analysis of partial N gene segment, isolate ANK/1079/2014 has taken place within clade A. In conclusion, MERS-CoV appears to have limited circulation in Arabian Peninsula and Middle-Eastern countries, it should be considered in mind that travel-related cases may export the virus outside these regions leading autochtonous infections in the other parts of the world.