The role of B cells during acute and latent infections with murine cytomegalovirus and Leishmania major

This thesis focuses on the role of B cells in mCMV and Leishmania major infection. B cells are an essential component of the adaptive immune system and play a key role in the humoral immune response. In mCMV infection we analyzed the influence of B cells on the virus-specific CD8 T cell response, in detail the role of B cells as IL-10 secreting cells, as source of immunoglobulin (Ig) and as antigen presenting cells. In Leishmania major infection we investigated the role of Ig in Th1 and Th2 directed disease.rnWe found in mCMV infection that the B cell secreted IL-10 suppresses effectively the acute virus-specific CD8 T cell response, while the IL-10 secreted by dendritic cell has no obvious effect. Ig has no effect in the acute virus-specific CD8 T cell response, but in memory response Ig is essential. If Ig is missing the CD8 T cell population remains high in memory response 135 days post infection. The complete absence of B cells dramatically reduces the acute virus-specific CD8 T cell response, while B cell reconstitution just partially rescues this dramatic reduction. A comparison of this reduction in a B cell free organism to an organism with depleted dendritic cells gave a similar result. To exclude a malfunction of the CD8 T cells in the B cell deficient mice, the decreased virus-specific CD8 T cell population was confirmed in a B cell depletion model. Further, bone marrow chimeras with a B cell compartment deficient for CD40-/- showed a decrease of the virus-specific response and an involvement of CD40 on B cells. Taken together these results suggest a role for B cells in antigen presentation during mCMV infection.rnFurther we took advantage of the altered mCMV specific CD8 T cell memory response in mice without Ig to investigate the memory inflation of CD8 T cells specific for distinct mCMV specifc peptides. Using a SIINFEKL-presenting virus system, we were able to shorten the time until the memory inflation occurs and show that direct presentation stimulates the memory inflation. rnIn Leishmania major infection, Ig of Th2 balanced BALB/c mice has a central role in preventing a systemic infection, although the ear lesions are smaller in IgMi mice without specific Ig. Here the parasite loads of ears and spleen are elevated, and an IMS-reconstitution does not affect the parasite load. In contrast in Th1 balanced C57BL/6 mice, reconstitution of IgMi mice with serum of either untreated or immunized mice decreased the parasite load of spleen and ear, further IMS treatment reduces the size of the spleen and the cytokine-levels of IL-10, IL-4, IL-2 and IFN-γ to a level comparable to wt mice. rn

Therapie und Prävention von opportunistischen Infektionen

Incidence as well as morbidity and mortality of opportunistic infections (OI) have declined remarkably since the availability of antiretroviral treatment (ART). Nearly half of all persons infected with HIV however do not know their HIV-status, and the diagnosis of an OI may be the first manifestation of their HIV infection. Therefore, knowledge of the presentation of OIs as well as their management should remain an essential part of clinicians' expertise. After starting ART the immune system will improve; in this context OI may be unmasked or the clinical presentation of known OI may worsen. Before starting ART therefore, it is essential to rule out any asymptomatic or latent OI. For the same reason, in the case of a known OI, the start of ART must often be deferred for some weeks after the start of OI treatment. Treatment of OIs is complex and often results in a large pill-burden for the patient with the potential for multiple drug-drug-interactions, particularly once ART has to be started. Many of the OI treatments are also associated with frequent drug side-effects and allergies. OIs can be prevented with specific antimicrobial agents once the CD4 have decreased below a defined threshold. However, the main prevention of OI is the timely recognition of HIV infection and an early start of ART before complications of OI appear.

Évaluation pharmacoéconomique d'un traitement préventif des infections respiratoires aiguës chez les patients atteints de maladie pulmonaire obstructive chronique

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Évaluation pharmacoéconomique d'un traitement préventif des infections respiratoires aiguës chez les patients atteints de maladie pulmonaire obstructive chronique

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Impfung gegen humane Papillomaviren (HPV) zur Prävention HPV 16/18 induzierter Zervixkarzinome und derer Vorstufen

Einleitung: Notwendige Voraussetzung für die Entstehung von Zervixkarzinomen ist eine persistierende Infektion mit humanen Papillomaviren (HPV). Die HPV-Typen 16 und 18 verursachen mit etwa 70% den überwiegenden Teil der Zervixkarzinome. Seit 2006/2007 stehen zwei Impfstoffe gegen HPV 16 und 18 zur Verfügung. Fragestellung: Wie effektiv ist die HPV-Impfung hinsichtlich der Reduktion von Zervixkarzinomen bzw. ihren Vorstufen (CIN)? Stellt die HPV-Impfung eine kosteneffektive Ergänzung zur derzeitigen Screeningpraxis dar? Gibt es Unterschiede bezüglich der Kosten-Effektivität zwischen den beiden verfügbaren Impfstoffen? Sollte aus gesundheitsökonomischer Perspektive eine Empfehlung für den Einsatz der HPV-Impfung gegeben werden? Falls ja, welche Empfehlungen bezüglich der Ausgestaltung einer Impfstrategie lassen sich ableiten? Welche ethischen, sozialen und juristischen Implikationen sind zu berücksichtigen? Methoden: Basierend auf einer systematischen Literaturrecherche werden randomisierte kontrollierte Studien zur Wirksamkeit der HPV-Impfungen für die Prävention von Zervixkarzinomen bzw. deren Vorstufen, den zervikalen intraepithelialen Neoplasien, identifiziert. Gesundheitsökonomische Modellierungen werden zur Beantwortung der ökonomischen Fragestellungen herangezogen. Die Beurteilung der Qualität der medizinischen und ökonomischen Studien erfolgt mittels anerkannter Standards zur systematischen Bewertung wissenschaftlicher Studien Ergebnisse: Bei zu Studienbeginn HPV 16/18 negativen Frauen, die alle Impfdosen erhalten haben, liegt die Wirksamkeit der Impfungen gegen HPV 16/18-induzierten CIN 2 oder höher bei 98% bis 100%. Nebenwirkungen der Impfung sind vor allem mit der Injektion assoziierte Beschwerden (Rötungen, Schwellungen, Schmerzen). Es gibt keine signifikanten Unterschiede für schwerwiegende unerwünschte Ereignisse zwischen Impf- und Placebogruppe. Die Ergebnisse der Basisfallanalysen der gesundheitsökonomischen Modellierungen reichen bei ausschließlicher Berücksichtigung direkter Kostenkomponenten von ca. 3.000 Euro bis ca. 40.000 Euro pro QALY (QALY = Qualitätskorrigiertes Lebensjahr), bzw. von ca. 9.000 Euro bis ca. 65.000 Euro pro LYG (LYG = Gewonnenes Lebensjahr). Diskussion: Nach den Ergebnissen der eingeschlossenen Studien sind die verfügbaren HPV-Impfstoffe wirksam zur Prävention gegen durch HPV 16/18 verursachte prämaligne Läsionen der Zervix. Unklar ist derzeit noch die Dauer des Impfschutzes. Hinsichtlich der Nebenwirkungen ist die Impfung als sicher einzustufen. Allerdings ist die Fallzahl der Studien nicht ausreichend groß, um das Auftreten sehr seltener Nebenwirkungen zuverlässig zu bestimmen. Inwieweit die HPV-Impfung zur Reduktion der Inzidenz und Mortalität des Zervixkarzinoms in Deutschland führen wird, hängt nicht allein von der klinischen Wirksamkeit der Impfstoffe ab, sondern wird von einer Reihe weiterer Faktoren wie der Impfquote oder den Auswirkungen der Impfungen auf die Teilnahmerate an den bestehenden Screeningprogrammen determiniert. Infolge der Heterogenität der methodischen Rahmenbedingungen und Inputparameter variieren die Ergebnisse der gesundheitsökonomischen Modellierungen erheblich. Fast alle Modellanalysen lassen jedoch den Schluss zu, dass die Einführung einer Impfung mit lebenslanger Schutzdauer bei Fortführung der derzeitigen Screeningpraxis als kosteneffektiv zu bewerten ist. Eine Gegenüberstellung der beiden verschiedenen Impfstoffe ergab, dass die Modellierung der tetravalenten Impfung bei der Berücksichtigung von QALY als Ergebnisparameter in der Regel mit einem niedrigeren (besseren) Kosten-Effektivitäts-Verhältnis einhergeht als die Modellierung der bivalenten Impfung, da auch Genitalwarzen berücksichtigt werden. In Sensitivitätsanalysen stellten sich sowohl die Schutzdauer der Impfung als auch die Höhe der Diskontierungsrate als wesentliche Einflussparameter der Kosten-Effektivität heraus. Schlussfolgerung: Die Einführung der HPV-Impfung kann zu einem verringerten Auftreten von Zervixkarzinomen bei geimpften Frauen führen. Jedoch sollten die Impfprogramme von weiteren Evaluationen begleitet werden, um die langfristige Wirksamkeit und Sicherheit beurteilen sowie die Umsetzung der Impfprogramme optimieren zu können. Von zentraler Bedeutung sind hohe Teilnahmeraten sowohl an den Impfprogrammen als auch - auch bei geimpften Frauen - an den Früherkennungsuntersuchungen. Da die Kosten-Effektivität entscheidend von der Schutzdauer, die bislang ungewiss ist, beeinflusst wird, ist eine abschließende Beurteilung der Kosten-Effektivität der HPV-Impfung nicht möglich. Eine langfristige Schutzdauer ist eine bedeutende Vorraussetzung für die Kosten-Effektivität der Impfung. Der Abschluss einer Risk-Sharing-Vereinbarung zwischen Kostenträgern und Herstellerfirmen stellt eine Option dar, um die Auswirkungen der Unsicherheit der Schutzdauer auf die Kosten-Effektivität zu begrenzen.

Identification Of Corynebacterium Spp. Isolated From Bovine Intramammary Infections By Matrix-assisted Laser Desorption Ionization-time Of Flight Mass Spectrometry.

Corynebacterium species (spp.) are among the most frequently isolated pathogens associated with subclinical mastitis in dairy cows. However, simple, fast, and reliable methods for the identification of species of the genus Corynebacterium are not currently available. This study aimed to evaluate the usefulness of matrix-assisted laser desorption ionization/mass spectrometry (MALDI-TOF MS) for identifying Corynebacterium spp. isolated from the mammary glands of dairy cows. Corynebacterium spp. were isolated from milk samples via microbiological culture (n=180) and were analyzed by MALDI-TOF MS and 16S rRNA gene sequencing. Using MALDI-TOF MS methodology, 161 Corynebacterium spp. isolates (89.4%) were correctly identified at the species level, whereas 12 isolates (6.7%) were identified at the genus level. Most isolates that were identified at the species level with 16 S rRNA gene sequencing were identified as Corynebacterium bovis (n=156; 86.7%) were also identified as C. bovis with MALDI-TOF MS. Five Corynebacterium spp. isolates (2.8%) were not correctly identified at the species level with MALDI-TOF MS and 2 isolates (1.1%) were considered unidentified because despite having MALDI-TOF MS scores >2, only the genus level was correctly identified. Therefore, MALDI-TOF MS could serve as an alternative method for species-level diagnoses of bovine intramammary infections caused by Corynebacterium spp.

Surgical Site Infections In Women And Their Association With Clinical Conditions.

Surgical site infections (SSIs) can affect body tissues, cavities, or organs manipulated in surgery and constitute 14% to 16% of all infections. This study aimed to determine the incidence of SSIs in women following their discharge from a gynecology outpatient clinic, to survey different types of SSIs among women, and to verify the association of SSIs with comorbidities and clinical conditions. Data were collected via analytical observation with a cross-sectional design, and the study was conducted in 1,026 women who underwent gynecological surgery in a teaching hospital in the municipality of Teresina, in the northeast Brazilian State of Piauí, from June 2011 to March 2013. The incidence of SSIs after discharge was 5.8% among the women in the outpatient clinic. The most prevalent surgery among the patients was hysterectomy, while the most prevalent type of SSI was superficial incisional. Comorbidities in women with SSIs included cancer, diabetes mellitus, and hypertension. Surveillance of SSIs during the post-discharge period is critical for infection prevention and control. It is worth reflecting on the planning of surgical procedures for patients who have risk factors for the development of SSIs.

Human Herpesvirus Infections Of The Central Nervous System: Laboratory Diagnosis Based On Dna Detection By Nested Pcr In Plasma And Cerebrospinal Fluid Samples.

Infections of the central nervous systems (CNS) present a diagnostic problem for which an accurate laboratory diagnosis is essential. Invasive practices, such as cerebral biopsy, have been replaced by obtaining a polymerase chain reaction (PCR) diagnosis using cerebral spinal fluid (CSF) as a reference method. Tests on DNA extracted from plasma are noninvasive, thus avoiding all of the collateral effects and patient risks associated with CSF collection. This study aimed to determine whether plasma can replace CSF in nested PCR analysis for the detection of CNS human herpesvirus (HHV) diseases by analysing the proportion of patients whose CSF nested PCR results were positive for CNS HHV who also had the same organism identified by plasma nested PCR. In this study, CSF DNA was used as the gold standard, and nested PCR was performed on both types of samples. Fifty-two patients with symptoms of nervous system infection were submitted to CSF and blood collection. For the eight HHV, one positive DNA result-in plasma and/or CSF nested PCR-was considered an active HHV infection, whereas the occurrence of two or more HHVs in the same sample was considered a coinfection. HHV infections were positively detected in 27/52 (51.9%) of the CSF and in 32/52 (61.5%) of the plasma, difference not significant, thus nested PCR can be performed on plasma instead of CSF. In conclusion, this findings suggest that plasma as a useful material for the diagnosis of cases where there is any difficulty to perform a CSF puncture.

Bay 41-2272 Activates Host Defence Against Local And Disseminated Candida Albicans Infections.

In our previous study, we have found that 5-cyclopropyl-2-[1-(2-fluoro-benzyl)-1H-pyrazolo[3,4-b]pyridine-3-yl]-pyrimidin-4-ylamine (BAY 41-2272), a guanylate cyclase agonist, activates human monocytes and the THP-1 cell line to produce the superoxide anion, increasing in vitro microbicidal activity, suggesting that this drug can be used to modulate immune functioning in primary immunodeficiency patients. In the present work, we investigated the potential of the in vivo administration of BAY 41-2272 for the treatment of Candida albicans and Staphylococcus aureus infections introduced via intraperitoneal and subcutaneous inoculation. We found that intraperitoneal treatment with BAY 41-2272 markedly increased macrophage-dependent cell influx to the peritoneum in addition to macrophage functions, such as spreading, zymosan particle phagocytosis and nitric oxide and phorbol myristate acetate-stimulated hydrogen peroxide production. Treatment with BAY 41-2272 was highly effective in reducing the death rate due to intraperitoneal inoculation of C. albicans, but not S. aureus. However, we found that in vitro stimulation of peritoneal macrophages with BAY 41-2272 markedly increased microbicidal activities against both pathogens. Our results show that the prevention of death by the treatment of C. albicans-infected mice with BAY 41-2272 might occur primarily by the modulation of the host immune response through macrophage activation.

Could leprosy reaction episodes be exacerbated by oral infections?

INTRODUCTION: This study evaluated whether leprosy reactions could be associated with oral infection. METHODS: Leprosy patients (n = 38) with (Group I) and without (Group II) oral infections were selected. Reactions were identified from the clinical and histopathological features associated with serum C-reactive protein (CRP) and10kDa interferon-gamma-induced protein (IP-10) levels, determined before and after elimination of the foci of infection. RESULTS: Group I presented more reactions than group II did, and improvement of the reactions after dental treatment. Serum CRP and IP-10 did not differ before and after the dental treatment, but differed between the groups. CONCLUSIONS: Oral infection could be an exacerbating factor in leprosy reactions.

The recurrence of leprosy reactional episodes could be associated with oral chronic infections and expression of serum IL-1, TNF-α, IL-6, IFN-γ and IL-10

The aim of this study was to determine whether the presence of leprosy reactional episodes could be associated with chronic oral infection. Thirty-eight leprosy patients were selected and divided into 2 groups: group I - 19 leprosy patients with oral infections, and group II - 19 leprosy patients without oral infections. Ten patients without leprosy, but presenting oral infections, were assigned to the control group. Leprosy patients were classified according to Ridley and Jopling classification and reactional episodes of the erythema nodosum type or reversal reaction were identified by clinical and histopathological features associated with serum IL-1, TNF-α, IL-6, IFN-γ and IL-10 levels. These analyses were performed immediately before and 7 days after the oral infection elimination. Patients from group I presenting oral infections reported clinical improvement of the symptoms of reactional episodes after dental treatment. Serum IL-1, TNF-α, IL-6, IFN-γ and IL-10 levels did not differ significantly before and after dental treatment as determined by the Wilcoxon test (p>0.05). Comparison of the 2 groups showed statistically significant differences in IL-1 and IL-6 at baseline and in IL-1, IL-6 and IL-10 on the occasion of both collections 7 days after therapy. Serum IL-6 and IL-10 levels in group I differed significantly at baseline compared to control (Mann-Whitney test; p<0.05). These results suggest that oral infection could be involved as a maintenance factor in the pathogenesis of leprosy reactional episodes.

Economic impact of treatment for surgical site infections in cases of total knee arthroplasty in a tertiary public hospital in Brazil

The aim of this study was to estimate the additional cost of treatment of a group of nosocomial infections in a tertiary public hospital. A retrospective observational cohort study was conducted by means of analyzing the medical records of 34 patients with infection after total knee arthroplasty, diagnosed in 2006 and 2007, who met the criteria for nosocomial infection according to the Centers for Disease Control and Prevention. To estimate the direct costs of treatment for these patients, the following data were gathered: length of hospital stay, laboratory tests, imaging examinations, and surgical procedures performed. Their costs were estimated from the minimum values according to the Brazilian Medical Association. The estimated cost of the antibiotics used was also obtained. The total length of stay in the ward was 976 days, at a cost of US$ 18,994.63, and, in the intensive care unit, it was 34 days at a cost of US$ 5,031.37. Forty-two debridement procedures were performed, at a cost of US$ 5,798.06, and 1965 tests (laboratory and imaging) were also performed, at a cost of US$ 15,359.25. US$ 20,845.01 was spent on antibiotics and US$ 1,735.16 on vacuum assisted closure therapy, microsurgical flaps, implant removal, spacer use, and surgical revision. The total additional cost of these cases of hospital infection in 2006 and 2007 was of US$ 91,843.75. Based on that, we demonstrate that the high cost of treatment for hospital infections emphasizes the importance of taking measures to prevent and control hospital infection.

A closer look at multiple-clone Plasmodium vivax infections: detection methods, prevalence and consequences

The naturally occurring clonal diversity among field isolates of the major human malaria parasite Plasmodium vivax remained unexplored until the early 1990s, when improved molecular methods allowed the use of blood samples obtained directly from patients, without prior in vitro culture, for genotyping purposes. Here we briefly review the molecular strategies currently used to detect genetically distinct clones in patient-derived P. vivax samples, present evidence that multiple-clone P. vivax infections are commonly detected in areas with different levels of malaria transmission and discuss possible evolutionary and epidemiological consequences of the competition between genetically distinct clones in natural human infections. We suggest that, when two or more genetically distinct clones are present in the same host, intra-host competition for limited resources may select for P. vivax traits that represent major public health challenges, such as increased virulence, increased transmissibility and antimalarial drug resistance.

Experimental infections with Paracoccidioides brasiliensis obtained from armadillos: comparison to clinical isolates

Paracoccidioides brasiliensis causes paracoccidioidomycosis (PCM) that is one of the most prevalent systemic human mycoses in Latin America. Armadillos show a high incidence of PCM infection and could, therefore, be a natural reservoir for this fungus. In this study were compared the virulence profiles of isolates obtained from nine-banded armadillos (Dasypus novemcinctus) (PbT1 and PbT4) and isolates from PCM patients (Pb265 and Bt83). Pathogenicity was evaluated by fungal load and analysis of colony morphology. Immunity against the fungus was tested by delayed type hypersensitivity test (DTH) and antibody quantification by ELISA. The higher virulence of PbT1 and PbT4 was suggested by higher fungal load in spleen and lungs. Armadillo isolates and Bt83 presented a cotton-like surface contrasting with the cerebriform appearance of Pb265. All isolates induced cellular and humoral immune responses in infected BALB/c mice. DTH reactions were similarly induced by the four isolates, however, a great variability was observed in specific antibody levels, being the highest ones induced by Bt83 and PbT4. The present work confirms that armadillos harbor P. brasiliensis, whose multiplication and induced immunity in experimentally infected mice are heterogeneous, resembling the behavior of isolates from human PCM. This study reinforces the possibility that armadillos play an important role in the biological cycle of this pathogen.

Estimating HIV-1 incidence using the serologic testing algorithm for recent HIV infections at HIV counseling and testing centers in the city of São Paulo, Brazil

The network of HIV counseling and testing centers in São Paulo, Brazil is a major source of data used to build epidemiological profiles of the client population. We examined HIV-1 incidence from November 2000 to April 2001, comparing epidemiological and socio-behavioral data of recently-infected individuals with those with long-standing infection. A less sensitive ELISA was employed to identify recent infection. The overall incidence of HIV-1 infection was 0.53/100/year (95% CI: 0.31-0.85/100/year): 0.77/100/year for males (95% CI: 0.42-1.27/100/year) and 0.22/100/ year (95% CI: 0.05-0.59/100/year) for females. Overall HIV-1 prevalence was 3.2% (95% CI: 2.8-3.7%), being 4.0% among males (95% CI: 3.3-4.7%) and 2.1% among females (95% CI: 1.6-2.8%). Recent infections accounted for 15% of the total (95% CI: 10.2-20.8%). Recent infection correlated with being younger and male (p = 0.019). Therefore, recent infection was more common among younger males and older females.