13 research outputs found
Increasing Incidences and Clonal Diversity of Methicillin-Resistant Staphylococcus aureus in the Nordic Countries-Results From the Nordic MRSA Surveillance
Methicillin-resistant Staphylococcus aureus (MRSA) is notifiable in Denmark, Finland, Iceland, Norway and Sweden. The prevalence of MRSA in this region has been low for many years, but all five countries experience increasing numbers of new cases. The aim of the study was to describe the molecular epidemiology in the Nordic countries 2009-2016. Numbers of new cases of MRSA from 1997 to 2016 were compared, and a database containing information on spa-type and place of residence or acquisition, for all new MRSA isolates from 2009 to 2016 was established. A website was developed to visualize the geographic distribution of the spa-types. The incidence of new MRSA cases increased in all Nordic countries with Denmark having 61.8 new cases per 100,000 inhabitants in 2016 as the highest. The number of new cases 2009 to 2016 was 60,984. spa-typing revealed a high genetic diversity, with a total of 2,344 different spa-types identified. The majority of these spa-types (N = 2,017) were found in 1-10 cases. The most common spa-types t127/CC1, t223/CC22, and t304/CC6:8 increased significantly in all Nordic countries during the study period, except for Iceland, while spa-type t002/CC5 decreased in the same four countries. The trends of other common spa-types were different in each of the Nordic countries. The Nordic countries were shown to share similar trends but also to have country-specific characteristics in their MRSA populations. A continued increasing numbers of MRSA will challenge the surveillance economically. A more selected molecular surveillance will probably have to be employed in the future
Rapid cross-border emergence of NDM-5-producing Escherichia coli in the European Union/European Economic Area, 2012 to June 2022
Whole genome sequencing data of 874 Escherichia
coli isolates carrying blaNDM-5 from 13 European Union/
European Economic Area countries between 2012 and
June 2022 showed the predominance of sequence
types ST167, ST405, ST410, ST361 and ST648, and
an increasing frequency of detection. Nearly a third
(30.6%) of these isolates were associated with
infections and more than half (58.2%) were predicted
to be multidrug-resistant. Further spread of E.
coli carrying blaNDM-5 would leave limited treatment
options for serious E. coli infections
Neutralizing activity and cellular immune responses induced in mice after immunization with apoptotic HIV-1/murine leukemia virus infected cells
Generation of neutralizing antibodies and divergence of SIVmac239 in cynomolgus macaques following short-term early antiretroviral therapy.
Neutralizing antibodies (NAb) able to react to heterologous viruses are generated during natural HIV-1 infection in some individuals. Further knowledge is required in order to understand the factors contributing to induction of cross-reactive NAb responses. Here a well-established model of experimental pathogenic infection in cynomolgus macaques, which reproduces long-lasting HIV-1 infection, was used to study the NAb response as well as the viral evolution of the highly neutralization-resistant SIVmac239. Twelve animals were infected intravenously with SIVmac239. Antiretroviral therapy (ART) was initiated ten days post-inoculation and administered daily for four months. Viral load, CD4(+) T-cell counts, total IgG levels, and breadth as well as strength of NAb in plasma were compared simultaneously over 14 months. In addition, envs from plasma samples were sequenced at three time points in all animals in order to assess viral evolution. We report here that seven of the 12 animals controlled viremia to below 10(4) copies/ml of plasma after discontinuation of ART and that this control was associated with a low level of evolutionary divergence. Macaques that controlled viral load developed broader NAb responses early on. Furthermore, escape mutations, such as V67M and R751G, were identified in virus sequenced from all animals with uncontrolled viremia. Bayesian estimation of ancestral population genetic diversity (PGD) showed an increase in this value in non-controlling or transient-controlling animals during the first 5.5 months of infection, in contrast to virus-controlling animals. Similarly, non- or transient controllers displayed more positively-selected amino-acid substitutions. An early increase in PGD, resulting in the generation of positively-selected amino-acid substitutions, greater divergence and relative high viral load after ART withdrawal, may have contributed to the generation of potent NAb in several animals after SIVmac239 infection. However, early broad NAb responses correlated with relatively preserved CD4(+) T-cell numbers, low viral load and limited viral divergence
HIV and SIV specific cellular immunity in macaque models
Cellular immunity is believed to be an important prerequisite for an
effective HIV vaccine. Accruing data from individuals able to contain
HIV-1 replication during natural infection underscores the contribution
of CD8+ T cells in viral control. Accordingly vaccine strategies designed
to generate these types of immune responses are now being explored.
We established a chromium release assay adapted for the detection of
HIV-1, HIV-2 and SIV specific CD8+ T cells. We further evaluated
combinations of monoclonal antibodies to human cytokines for their
cross-reactivity with rhesus and cynomolgus macaque cytokines and
compared spontaneous and mitogen-induced cytokine production in
peripheral blood mononuclear cells (PBMC) from all species, using ELISA
as well as enzyme-linked immune spot assay (ELISpot). The proportional
distribution of the different cytokines in terms of PBMC synthezsizing
different cytokines, were similar in all species. These methods were used
together with a proliferation assay for the monitoring of cellular immune
responses following vaccination or infection.
A prime boost immunization protocol including HIV-2 recombinant avipox
vaccine (ALVAC) followed by HIV-2 gp125 protein or V3 peptides induced
protection in 4 of 10 immunized monkeys. None of the 4 monkeys receiving
ALVAC HIV-2 alone were protected. No correlation was found between any of
the studied immunologic parameters and protection. However, among 6
investigated macaques lymphocyte proliferative responses to V3 peptides
were detected in 2 protected but in none of 4 non-protected animals. In
another study we assessed immune responses in macaques vaccinated with a
DNA prime MVA boost HIV/SIV vaccine either intramuscularly and mucosally
or intramuscularly only. In this study we found a correlation between the
breadth of elicited immune responses prior to SHIV challenge and the
viral load 14 days after challenge. In addition, earlier control of viral
replication was observed in animals immunized both mucosally and
intramuscularly than in animals immunized intramuscularly only.
A further support for the important role of cellular immunity comes from
studies of highly HIV exposed uninfected individuals. HIV-specific CD8+
and CD4+ T cell responses have been observed in these individuals but no
serum antibodies. Virusspecific CTL was detected in 2 of 3 multiple HIV-2
exposed seronegative monkeys in our study. Following intrarectal
challenge with SIVsm, one monkey was completely protected and two monkeys
showed suppressed viral replication. SIV specific CTL as well as SIV
specific lymphoproliferation was demonstrated in monkeys exposed to low
doses of SIVsm, in the absence of antibodies and detectable virus.
Despite the presence of cellular immune responses the animals became
infected after an intrarectal challenge with a higher dose of SIVsm.
In conclusion our data show the importance of inducing a broad and strong
immune response consisting of both cellular and humoral immunity for
control of virus replication. Especially functional CD8+ T cells seem to
be of vital importance
Enhanced simian immunodeficiency virus-specific immune responses in macaques induced by priming with recombinant Semliki Forest virus and boosting with modified vaccinia virus Ankara
The immunogenicity of two vector-based vaccines, either given alone or in a prime-boost regimen, was investigated. Cynomolgus macaques were immunised with modified vaccinia virus Ankara (MVA) expressing simian immunodeficiency virus (SIV)macJ5 env, gag-pol, nef, rev, and tat genes (MVA-SIVmac) or primed with a Semliki forest virus (SFV) vaccine expressing the same genes (SFV-SIVmac) and boosted with MVA-SIVmac. Generally, antibody responses, T-cell proliferative responses and cytotoxic T-cell responses remained low or undetectable in vaccinees receiving MVA-SIVmac or SFV-SIVmac alone. In contrast, monkeys who first received SFV-SIVmac twice and then were boosted with MVA-SIVmac showed increased antibody responses as well as high T-cell proliferative responses. Three of these vaccinees had cytotoxic T-lymphocytes directed against three or four of the gene products. No evidence of protection was seen against an intrarectal heterologous SIVsm challenge given 3 months after the last immunisation. The study demonstrates a prime-boost strategy that efficiently induces both humoral and cellular immune responses. © 2001 Elsevier Science Ltd. All rights reserved.SCOPUS: ar.jinfo:eu-repo/semantics/publishe
Generation of neutralizing antibodies and divergence of SIVmac239 in cynomolgus macaques following short-term early antiretroviral therapy
Neutralizing antibodies (NAb) able to react to heterologous viruses are generated during natural HIV-1 infection in some individuals. Further knowledge is required in order to understand the factors contributing to induction of cross-reactive NAb responses. Here a well-established model of experimental pathogenic infection in cynomolgus macaques, which reproduces long-lasting HIV-1 infection, was used to study the NAb response as well as the viral evolution of the highly neutralization-resistant SIVmac239. Twelve animals were infected intravenously with SIVmac239. Antiretroviral therapy (ART) was initiated ten days post-inoculation and administered daily for four months. Viral load, CD4+ T-cell counts, total IgG levels, and breadth as well as strength of NAb in plasma were compared simultaneously over 14 months. In addition, envs from plasma samples were sequenced at three time points in all animals in order to assess viral evolution. We report here that seven of the 12 animals controlled viremia to below 104 copies/ml of plasma after discontinuation of ART and that this control was associated with a low level of evolutionary divergence. Macaques that controlled viral load developed broader NAb responses early on. Furthermore, escape mutations, such as V67M and R751G, were identified in virus sequenced from all animals with uncontrolled viremia. Bayesian estimation of ancestral population genetic diversity (PGD) showed an increase in this value in non-controlling or transient-controlling animals during the first 5.5 months of infection, in contrast to virus-controlling animals. Similarly, non- or transient controllers displayed more positively-selected amino-acid substitutions. An early increase in PGD, resulting in the generation of positively-selected amino-acid substitutions, greater divergence and relative high viral load after ART withdrawal, may have contributed to the generation of potent NAb in several animals after SIVmac239 infection. However, early broad NAb responses correlated with relatively preserved CD4+ T-cell numbers, low viral load and limited viral divergence