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    Investigation and long-term monitoring of the presence of neutralizing antibody in patients with COVID-19 disease of different clinical severity
    (Wiley, 2022) Kaygusuz, Sedat; Korukluoglu, Gulay; Cosgun, Yasemin; Sahin, Omer; Arslan, Ferhat
    Understanding the immune responses elicited by severe acute respiratory syndrome virus (SARS-CoV-2) infection is critical to public health policy and vaccine development and prevention of reinfections for COVID-19. It is important to know the neutralizing capacity of antibodies and to monitor their persistence. Patients with COVID-19 were divided into four groups (severe-critical, moderate, mild, and asymptomatic) according to their clinical severity. Antibodies against SARS-CoV-2 spike viral surface protein were investigated by ELISA method 3 and 9 months after the onset of the disease. Neutralizing antibody (NAb) response was evaluated by microneutralization test. Patients who received at least two doses of COVID-19 vaccine after illness were enrolled. SARS-CoV-2 immunoglobulin G (IgG) and NAb titers were shown to be strongly correlated with disease severity. Anti-SARS-CoV-2 IgG and NAb levels were found to be compatible with each other. After 9 months of follow-up, both IgG and NAb levels continued unabated in individuals who had the disease. In individuals who received at least two doses of the vaccine, these levels increased, except for severe-critical patients. High levels of anti-SARS-CoV-2 IgG are indicative, as it is difficult to investigate NAb in routine laboratories. At the same time, it can be predicted that this period may be much longer if it continues for at least 9 months and is reinforced with vaccination.
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    Molecular Characterization of Measles Viruses in Turkey (2010-2011): First Report of Genotype D9 Involved in an Outbreak in 2011
    (Wiley, 2013) Kalaycioglu, Atila T.; Baykal, Atakan; Guldemir, Dilek; Bakkaloglu, Zekiye; Korukluoglu, Gulay; Coskun, Aslihan; Durmaz, Riza
    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. J. Med. Virol. 85:2128-2135, 2013. (c) 2013 Wiley Periodicals, Inc.
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    Monitoring Genetic Diversity of Influenza A(H1N1)pdm09 Virus Circulating during the Post-Pandemic Period in Turkey
    (Natl Inst Infectious Diseases, 2013) Guldemir, Dilek; Kalaycioglu, Atila T.; Altas, A. Basak; Korukluoglu, Gulay; Durmaz, Riza
    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.