Ira Gjenero-Margan

Enumeration of Haemagglutinin‐specific CD8+ T Cells after Influenza Vaccination Using MHC Class I Peptide Tetramers

With emergence of MHC class I tetramers loaded with CD8+ T‐cell viral epitopes, it is possible to study virus‐specific CD8 cells in humans during infection and after vaccination. MHC class I tetramers was used to detect the frequency of haemagglutinin (HA)‐specific T cells in 26 healthy influenza‐vaccinated humans. Peripheral blood was collected before, and 7, 14 and 28 days after vaccination. Four‐colour flow cytometry was used for monitoring of vaccine induced T‐cell response. In 15 donors, two‐ to fivefold increase in frequency of HA‐specific T cells was observed 7 days after vaccination. In addition, in 12 of these donors, this increase was accompanied with fourfold increase of H1N1 antibody titre. The increase in frequency of HA‐specific CD8+/IFN‐γ+ cells was low and peaked 28 days after vaccination in three of the six donors tested. Frequencies of HA‐specific CD8+ T cells and antibody titre returned to prevaccination values 1 year after vaccination. Subunit influenza vaccines have the ability to induce HA‐specific CD8+ cells. As the immune response to this vaccine decreased significantly after 1 year, our results confirm the importance of annual immunization for adequate protection.

Outcome of influenza vaccination in combat-related post-traumatic stress disorder (PTSD) patients

Post‐traumatic stress disorder (PTSD) is an anxiety disorder that can occur after exposure to extreme traumatic experience such as war trauma, and is accompanied by fear, helplessness or horror. Exposure to trauma can result in immune dysregulation and influence susceptibility to infectious disease as well as vaccine efficacy. The aim of the study was to determine the relation of psychological stress and the immune response to influenza vaccination in combat‐related PTSD patients (n = 28). Detection of anti‐viral antibody titre was performed by inhibition of haemagglutination assay. Ex vivo tetramer staining of CD8+ T lymphocytes was used to monitor T cells specific for human leucocyte antigen (HLA)‐A*0201‐restricted influenza A haemagglutinin antigens before and after vaccination. Twenty patients showed a fourfold antibody titre increase to one or both influenza A viral strains, and 18 of them showed the same response for both influenza B viral strains. Ten of 15 healthy controls showed a fourfold rise in antibody titre to both influenza A viral strains and eight of them showed the same response for both influenza B viral strains. HLA‐A*0201+ PTSD patients (n = 10) showed a significant increase of influenza‐specific CD8 T cells after vaccination. Although those PTSD patients had a lower number of influenza‐specific CD8+ T cells before vaccination compared to HLA‐A*0201+ healthy controls (n = 6), there was no difference in influenza A antibody titre between PTSD patients and control subjects before vaccination. The generated humoral and cellular immune response in PTSD patients argues against the hypothesis that combat‐related PTSD in war veterans might affect protection following influenza vaccination.

Seroprevalence and entomological study on chikungunya virus at the Croatian littoral

During 2011-2012, a total of 1008 serum samples from randomly selected inhabitants of seven Croatian counties located on the Adriatic Coast were tested for the presence of chikungunya virus (CHIKV) IgG antibodies using indirect immunofluorescence assay. Nine participants (0.9%) from four counties were found to be seropositive to CHIKV. Seroprevalence varied from 0.5% to 1.8% between counties. Additionally, a total of 3,699 mosquitoes were captured in 126 localities from August 16 to September 24, 2011. Three mosquito species were found: Ae. albopictus (3010/81.4%), Cx. pipiens (688/18.6%) and only one specimen of the Cs. longiareolata. Female mosquitoes (N = 1,748) were pooled. All pools tested negative for CHIKV RNA using a real-time RT-PCR.

Role of epidemiologic information system in sudden death prevention among Croatia's haemodialysis patients

The main aim of Croatias epidemiological information system is to enable the monitoring of infectious diseases as well as to enable necessary interventions. Its 24-hour epidemiologic alert mechanism made it possible for initial reports of sudden death clusters in haemodialysis units to reach epidemiologists on the night of 12 October 2001. The alert about the sudden deaths among haemodialysis patients in two hospitals has prompted us to do an epidemiological inquiry during that night and early the next morning. It looked at suspicions of a possible link between Baxter Plivadial P-15 lot 2001F075 dialyser and these deaths. As the suspicion was based on a small amount of data, it needed confirmation from a countrywide inquiry involving the other 40 haemodialysis units. A phone inquiry showed that 23 haemodialysis deaths occurred on 8–13 October 2001. It suggested that also dialyser of a different type and lot (P-18 2001B17R) should be incriminated. During the inquiry (October 13), all haemodialysis units were informed of the suspicions regarding incriminated dialysers, and of the necessity of temporary withdrawal of these from use. The withdrawal on 13 October of incriminated dialysers stopped the deaths among haemodialysis patients. No more such sudden deaths have been recorded since that could be linked either to the described period or to this clinical picture.