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Ivarsson S.,The Swedish Institute for Communicable Disease Control | Lindqvist R.,Swedish University of Agricultural Sciences
International Journal of Food Microbiology | Year: 2013

Identification and prioritisation of food safety interventions requires an understanding of the relationship between food, pathogens and cases. Such understanding can be gained through different approaches, e.g. microbial subtyping to attribute cases of foodborne disease to food vehicles or other sources of illness. In this study, Listeria monocytogenes isolates (n. = 166) from (i) three categories of ready-to-eat (RTE) foods, (ii) food processing plant environments, and (iii) human listeriosis cases, all sampled during 2010 in Sweden, were subtyped. In addition, 121 isolates from human listeriosis cases, collected 2005-2009, were subtyped. Subtyping consisted of both serotyping (conventional method and PCR) and genotyping using pulsed-field gel electrophoresis (PFGE). Serotype 1/2a dominated in all three groups of isolates (range 73-96%). Eighteen percent of the human isolates (2010) belonged to serotype 4b, but only 1.4% of the food isolates. The food isolates differentiated into 19 pulsotypes (ID. = 0.843), the human isolates collected 2010 into 31 pulsotypes (ID. = 0.950) and the processing plant isolates into 22 pulsotypes (ID. = 0.991). Six of the pulsotypes were shared between the food and human isolates. These pulsotypes comprised 42% of the human isolates and 59% of the food isolates. For some processing plants, there was suggested persistence of one or more specific L. monocytogenes strains, as indicated by repetitive isolation of the same pulsotype from food. This study indicated the presence of L. monocytogenes in the processing plant environment as a likely source of contamination of gravad and cold-smoked fish, and this food category as an important source of human exposure to the pathogen. © 2013 Elsevier B.V.

Cagigi A.,Karolinska University Hospital | Pensieroso S.,Karolinska Institutet | Ruffin N.,Karolinska Institutet | Sammicheli S.,Karolinska Institutet | And 5 more authors.
Vaccine | Year: 2013

The relevance of CD4+T-cells, viral load and age in the immunological response to influenza infection and vaccination in HIV-1 infected individuals has previously been pointed out. Our study aimed at assessing, in the setting of 2009 A(H1N1)pdm09 influenza vaccination, whether quantification of activation-induced deaminase (AID) expression in blood B-cells may provide additional indications for predicting antibody response to vaccination in HIV-1 infected patients with similar CD4+T-cell counts and age. Forty-seven healthy controls, 37 ART-treated and 17 treatment-naïve HIV-1 infected patients were enrolled in the study. Blood was collected prior to A(H1N1)pdm09 vaccination and at 1, 3 and 6 months after vaccination. Antibody titers to A(H1N1)pdm09 vaccine were measured by hemagglutination inhibition (HI) assay while the mRNA expression levels of AID were measured by quantitative real time PCR. Upon B-cell activation in vitro, AID increase correlated to antibody response to the A(H1N1)pdm09 vaccine at 1 month after vaccination in all individuals. In addition, the maximum expression levels of AID were significantly higher in those individuals who still carried protective levels of A(H1N1)pdm09 antibodies after 6 months from vaccination. No correlation was found between CD4+T-cell counts or age at vaccination or HIV-1 viral load and levels of A(H1N1)pdm09 antibodies. Assessing AID expression before vaccination may be an additional useful tool for defining a vaccination strategy in immune-compromised individuals at risk of immunization failure. © 2013 Elsevier Ltd.

PubMed | The Swedish Institute for Communicable Disease Control, Karolinska Institutet, Lund University and Stockholm South General Hospital
Type: Journal Article | Journal: Human vaccines & immunotherapeutics | Year: 2013

Viremia during human immunodeficiency virus type-1 (HIV-1) infection results in progressive impairment of several components of the immune system. Here a unique model of repeated treatment interruptions (TIs) was used with the aim to reveal the effect of controlled short-term viremia on innate stimuli responsiveness and circulating dendritic cells (DCs). Sequential peripheral blood samples from HIV-1-infected patients on combination antiretroviral therapy, subjected to repeated TI cycles as part of a therapeutic DNA vaccination study, were analyzed. In vitro responsiveness of peripheral blood mononuclear cells to toll-like receptor (TLR) stimuli was analyzed by cytokine secretion, and frequencies of plasmacytoid DCs (pDCs) and myeloid DCs (mDCs) were monitored by flow cytometry. These parameters were found not to be significantly different between the vaccinated and placebo groups. Instead, independent of vaccination altered in vitro TLR responsiveness was observed in parallel with TI cycles. TLR7/8-triggered secretion of IL-12 and IFN-, as well as TLR9-triggered secretion of IL-12, was hyperactivated. In contrast, expression of IFN- after TLR9 stimulation decreased during the initial cycle of TI. Reduced frequencies of pDCs and mDCs, compared with baseline, were noted before and during the second TI, respectively. Furthermore, spontaneous ex vivo release of IL-12 from PBMC was noted during cycles of TI. In conclusion, these results suggest that consequences of short-term TI include dysregulated TLR responses and fluctuations in the frequencies of circulating DCs. Knowledge of these immunological factors may influence the continuation of stringent treatment schedules during HIV infections.

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