BACKGROUNDEncephalitis continues to result in substantial morbidity and mortality worldwide. Advances in diagnosis and management have been limited, in part, by a lack of consensus on case definitions, standardized diagnostic approaches, and priorities for research.METHODSIn March 2012, the International Encephalitis Consortium, a committee begun in 2010 with members worldwide, held a meeting in Atlanta to discuss recent advances in encephalitis and to set priorities for future study.RESULTSWe present a consensus document that proposes a standardized case definition and diagnostic guidelines for evaluation of adults and children with suspected encephalitis. In addition, areas of research priority, including host genetics and selected emerging infections, are discussed.CONCLUSIONSWe anticipate that this document, representing a synthesis of our discussions and supported by literature, will serve as a practical aid to clinicians evaluating patients with suspected encephalitis and will identify key areas and approaches to advance our knowledge of encephalitis.

Encephalitis results in substantial morbidity and mortality worldwide. Specific etiologies are identified in <50% of cases, in part due to lack of consensus on case definitions and standardized diagnostic approaches. Advances in encephalitis are hampered by the rarity and heterogeneity of cases, highlighting the need for a collaborative international approach. In March 2012, the International Encephalitis Consortium held a meeting in Atlanta to discuss recent advances in encephalitis and to set priorities for future study. This consortium is an ad-hoc committee begun in 2010 with members from the Americas, Europe, Australia, Africa, and Asia. The mission of the consortium is to advance knowledge of the causes, diagnostic strategies, treatment, and outcome of encephalitis, and to implement interventions based upon this knowledge. Topics discussed at the meeting included: (1) standardization of a case definition for encephalitis, (2) development of practical diagnostic algorithms for evaluation of patients, (3) the role of host genetics in encephalitis, and (4) priorities for the study of selected emerging infectious diseases. Here we present a consensus document that synthesizes our discussions and recent literature, with the goals of aiding clinicians evaluating patients with suspected encephalitis and of identifying priorities and approaches to advance knowledge of encephalitis.

There have been few surveys of Streptococcus pneumoniae and Neisseria meningitidis carriage in sick or frail elderly people who, with the very young, comprise the group who are at highest risk for pneumococcal disease. We studied pneumococcal carriage among participants in a pneumococcal immunisation study in the frail elderly.Methods: Subjects aged >= 60 years were recruited from a large tertiary referral hospital in Sydney, Australia. Nose and throat swabs were collected at the time of enrolment and 12 months after immunisation. Results: Before immunisation, only 1 of 315 participants was identified as a nasal carrier of S. pneumoniae; another was identified as throat carrier of N. meningitidis. None of the participants examined after immunisation was carrying either S. pneumoniae or N. meningitidis.Conclusion: The low rate of pneumococcal carriage in this population of hospitalised elderly patients was unexpected. The most likely reason is that long-term carriage is rare in this population and suggests that pneumococcal disease primarily follows recent acquisition of S. pneumoniae types not associated with carriage. (C) 2010 Elsevier Ltd. All rights reserved.

MucosalImmunology | VOLUME 2 SUPPLEMENT 1 | JUNE 2009 S1 nature publishing group B Cells & lymphoid organogenesis

a National Centre for Immunization Research and Surveillance Sydney, NSW, Australia b The University of Sydney, Sydney, NSW, Australia c Discipline of Medicine, Geriatric Medicine, Westmead Hospital, Sydney, NSW, Australia d School of Public Health and Community Medicine, The University of New South Wales, Australia e The Australian Red Cross Blood Services, Sydney, NSW, Australia f Research Unit of Transfusion Medicine and Immunogenetics, Faculty of Medicine, University of Sydney, Australia

Advanced age has been associated with a wide range of defects in both the innate and adaptive immune systems including diminished specific antibody responses that increase the risk of invasive pneumococcal disease (IPD) and limit the effectiveness of vaccines. However, the elderly are a heterogeneous group and measures of overall frailty may be a better indicator of disease susceptibility (or vaccine response) than chronological age alone.Aim: To evaluate the immunogenicity of the 7-valent conjugated pneumococcal vaccine (PCV7) versus 23-valent polysaccharide vaccine (23vPPV) and compare the immune response to four serotypes (4, 68,18C and 19F), with respect to age or frailty in an elderly population of previously unvaccinated hospitalized patients.Method: 241 patients aged 60 years and over, recruited between 16 May 2005 and 20 February 2006, were randomised to 23PPV or PCV7 vaccine. We measured Frailty Index (FI), Barthel index and the MiniMental State. Serotype-specific IgG was measured by ELISA at base line and 6 months after vaccination. Antibody responses were defined by the ratio of post-vaccination to pre-vaccination IgG antibody concentration (poor < 2-fold increase, acceptable >= 2.0 to 3.99-fold and strong >= 4.0-fold increase).Results: Pre-immunization IgG was generally low and did not differ significantly by age or frailty. Post-immunization, IgG increased to all four serotypes; acceptable or strong response ranged between 29% for (613) and 57% for (18C). There was no significant difference between the two vaccine types (23PPV versus PCV7). At 6 months post-vaccination, the highest geometric mean IgG concentrations (GMCs) were seen for serotype 19F and the lowest for serotype 4. Although there was some variation by serotype, responses after vaccination were lowest in the most frail or aged subjects.Conclusions: Pneumococcal vaccines are perceived to offer low protection in the frail elderly, but our study showed that the proportion of this vulnerable population with acceptable responses is encouraging. Frailty, as measured by the Frailty Index, appears to be a better predictor of immune response to pneumococcal vaccines than age alone. (C) 2008 Elsevier Ltd. All rights reserved.

Introduction: The elderly, despite being most at risk for invasive pneumococcal disease, respond poorly to polysaccharide vaccine. Conjugated vaccine technology overcomes this problem in children aged <2 years, but conjugated vaccines are not licensed for use in adults. Clinical predictors of response to vaccines other than chronological age may assist in targeting adults in most need of a more immunogenic vaccine. An index of frailty (FI) has gained support as a measurement tool, but has not been examined as a predictor of immune responsiveness. Aims: To determine the response to 23 valent polysaccharide (PPV) and 7-valent conjugate (PCV7) pneumococcal vaccines in the elderly by level of frailty. Methods: A randomized controlled clinical trial of hospitalized elderly was conducted. Subjects were randomised to receive PPV or PCV7; those who received PCV7 received PPV 6 months later. Serology was measured by enzyme immunoassay (ELISA) against four serotypes, 4, 6B, 18C and 19F. Results: For all four sero types there were statistically significant increases in geometric mean concentrations after immunization; however there were no difference between 23PPV and PCV7. There association between frailty scores and geometric mean concentrations (GMC) varied by serotype. For serotype 4, there was a clear relationship between response and frailty - responses decreased with increasing frailty. This relationship was seen to a lesser degree for serotypes 18C and 19F. Type 6B is considered to be a poor immunogenic and there were very little change in both groups from baseline to 6 months. Conclusions: We demonstrated the more frail patients had a poorer immune response to polysaccharide and conjugate pneumococcal vaccines, except for serotype 6B, where responses were poor in all groups. The use of a frailty index may be more suitable than age alone to determine people at risk of poor vaccine responses.

ABSTRACT

ABSTRACT We studied the evolution of human immunodeficiency virus type 1 (HIV-1) in a cohort of long-term survivors infected with an attenuated strain of HIV-1 acquired from a single source. Although the cohort members experienced differing clinical courses, we demonstrate similar evolution of HIV-1 nef /long-terminal repeat (LTR) sequences, characterized by progressive sequence deletions tending toward a minimal nef /LTR structure that retains only sequence elements required for viral replication. The in vivo pathogenicity of attenuated HIV-1 is therefore dictated by viral and/or host factors other than those that impose a unidirectional selection pressure on the nef /LTR region of the HIV-1 genome.

HIV-1 infection and compartmentalization in diverse leukocyte targets significantly contribute to viral persistence during suppressive highly active antiretroviral therapy (HAART). Longitudinal analyses were performed on envelope sequences of HIV-1 populations from plasma, CD4+ and CD8+ T lymphocytes in 14 patients receiving HAART and 1 therapy-naive individual. Phylogenetic reconstructions and analysis of molecular variance revealed that HIV-1 populations in CD4+ and CD8+ T cells remained compartmentalized over time in most individuals. Analyses of viral genetic variation demonstrated that, despite compartmentalization remaining over time, viral subpopulations tended not to persist and evolve but instead broke down and became reconstituted by new founder viruses. Due to the profound impact of HAART on viral evolution, it was difficult to discern whether these dynamics were ongoing during treatment or predominantly established prior to the commencement of therapy. The genetic structure and viral founder effects observed in serially sampled T lymphocyte populations supported a scenario of metapopulation dynamics in the tissue(s) where different leukocytes become infected, a factor likely to contribute to the highly variable way that drug resistance evolves in different individuals during HAART.

Polymorphisms of human Fc gamma-receptor IIA (Fc gamma RIIA) and mannose-binding lectin (MBL) genes have been associated with susceptibility to or severity of some infectious diseases. In order to investigate whether these genetic factors might influence susceptibility to infection with the severe acute respiratory syndrome-associated coronavirus (SARS-Cov) as well as the course and severity of the infection, we evaluated polymorphisms of Fc gamma RIIA and MBL genes in DNA samples from a group of approximately 180 people from Hong Kong who were infected with SARS-Cov. These included 132 patients who had moderate course of SARS infection (home subgroup), 26 patients with a severe course requiring treatment in an intensive care ward (ICU subgroup) and a subgroup of 22 patients who died from SARS (deceased subgroup). A total of 200 normal blood donors from the same region were used as controls. A significant association was found between the Fc gamma RIIA-R/R131 genotype and a severe course of SARS, with higher frequency of homozygosity for Fc gamma RIIA-R/R131 in the ICU subgroup of SARS patients when compared with controls (P = 0.03; odds ratio: 3.2; 95% confidence interval: 1.1-9.1). In comparison with controls, a significant difference in linear trend distribution of Fc gamma RIIA genotypes was seen among the severe SARS patients (ICU and deceased subgroups) without co-morbidity, and the incidence of Fc gamma RIIA-H/H131 was lower in these patients as well. There were no significant differences in MBL genotypes and allele frequencies among SARS patients and controls. The study reveals that in addition to age and co-morbidity, Fc gamma RIIA polymorphism of individuals may also influence outcome after infection with the SARS-Cov.

Amino acid residues 90-120 of the prion protein (PrP) are likely to be critical for the conversion of PrP(c) to PrP(sc) in the transmissible spongiform encephalopathies. We raised 10 monoclonal antibodies against the 90-120 amino acid region, mapped the epitope specificity of these anti-PrP antibodies, and investigated the expression of epitopes recognized by the antibodies in both PrP(c) and PrP(sc). Four out of five of the anti-PrP antibodies raised in a prion knockout mouse immunized with the linear peptide of PrP90-120 could detect PrP(sc) in 'native' and denatured forms and PrP(c) in normal cells, as well as recognize epitopes within PrP93-112 residues. In contrast, the other six anti-PrP reagents, including five raised from the two knockout mice immunized with conformationally modified PrP90-120 peptide, could detect PrP(c) and recognize epitopes within PrP93-107 residues. Four of these reagents could also detect denatured PrP(sc) on western blots but not PrP(sc) plaques in brain tissue. The results indicate that residues PrP93-102 are exposed in PrP(c) but are buried upon conversion to the PrP(sc) isoform. Furthermore, PrP103-107 residues are partially buried in PrP(sc) while only the PrP107-112 epitope remains exposed, suggesting that the region PrP93-112 undergoes conformational changes during its conversion to PrP(sc).

Objective. To determine whether the bispectral index (BIS) monitor could be used to guide physicians in titrating propofol to an effective safe level of deep sedation for children undergoing painful medical procedures.Design. Multiphase clinical trial.Setting. Outpatient treatment center of a university children's hospital.Patients. Pediatric outpatients undergoing painful medical procedures.Interventions. Patients were sedated with propofol for the procedures. Patients were monitored with a BIS monitor, and the BIS score was correlated with the patient's clinical level of sedation. The BIS score was then used as a guide to titrate propofol in the last phase of the study.Measurements and Main Results. The study consisted of 3 phases. In a chart review of data for 154 children who underwent 212 procedures, propofol was found to be safe and effective, with consistent dosing among the intensivists administering the medication. The children received a mean bolus dose of propofol of 1.56 mg/kg, with a mean total dose of propofol of 0.33 mg/kg per minute for the duration of the procedure. In the second phase, 21 patients ranging in age from 27 weeks to 18 years, with normal neurologic function, were sedated with propofol. An observer who was blinded to the BIS scores recorded clinical levels of sedation and reactivity (with a modified Ramsay scale and reactivity score) every 1 to 3 minutes. Another observer recorded the BIS scores at the same times. A total of 275 data points were collected and evaluated. All data points from the times at which patients were considered to be sedated adequately were used to construct a normal distribution of BIS scores. The mean BIS score was 62. This distribution was used to predict that a maximal BIS score of 47 was needed to ensure adequate sedation for 90% of the population. In the third phase of the study, an algorithm was devised to determine the target BIS score necessary for adequate sedation of 95% of the patients. We chose an initial BIS score of 50 (at which 85% of the patients in phase 2 were sedated) because of the possibility of data from phase 2 being skewed toward oversedation. Propofol was administered by an intensivist in an attempt to maintain the target BIS score. A blinded observer noted the patient's clinical level of sedation. In this group, there were 2 failures, ie, patients were clinically uncomfortable despite a BIS score of ≤50, representing only 90% success. Therefore, with the algorithm, propofol was titrated to sedate the next patients to a BIS score of 45. These patients required a mean bolus dose of 1.47 mg/kg and a mean total dose of 0.51 mg/kg per minute to maintain a BIS score of 45. They awakened in 12.75 minutes. All patients were sedated adequately, all procedures were successful, and no patients experienced complications from the sedation. To eliminate variability in the way propofol was dosed, the next 10 patients were given propofol according to a standardized protocol. These 10 children received an initial bolus of 1 mg/kg, with incremental bolus doses of 0.5 mg/kg per dose (maximum: 20 mg) to achieve and to maintain a BIS score of 45. With this protocol, all patients were sedated adequately and none experienced complications from the sedation. The patients required a mean bolus dose of 2.23 mg/kg and a mean dose of 0.52 mg/kg per minute to maintain a BIS score of 45. The mean time until awakening was 14.9 minutes. Regarding the total dose over time and the time until awakening, there was no statistical significance between this group and the group sedated to a BIS score of 45 without the dosing protocol.Conclusion. The BIS monitor can be a useful monitoring guide for the titration of propofol by physicians who are competent in airway and hemodynamic management, to achieve deep sedation for children undergoing painful procedures.

Acute rejection is a leading cause of early renal-allograft failure. The human Fc gamma receptor IIA (FcgammaRIIA) forms an essential link between the humoral branch and the effector cells of the immune system. In this study, we examined FcgammaRIIA genotypes in renal-allograft recipients (rejectors) with acute graft rejection and in a number of control groups to investigate a possible association between FcgammaRIIA polymorphism and acute renal-allograft rejection. The distribution of the genotypes in the study patient group differed from the control groups. The frequency of homozygosity for FcagammaRIIA-R/R131 in the rejectors was significantly higher than that in the recipients (nonrejectors) with well-functioning renal allografts and in blood donors (P< 0.05). In comparison with the control groups, the rejectors displayed a higher R131 allele frequency (P< 0.05) and a lower H131 allele frequency (P< 0.05). These results reveal a significant association between FcgammaRIIA-R/R131 and acute renal-graft rejection, and it is likely that FcgammaRIIA polymorphisms could be useful markers for potential risk of rejection.

Objective. Acute asphyxial asthma (AAA) is well described in adult patients and is characterized by a sudden onset that may rapidly progress to a near-arrest state. Despite the initial severity of AAA, mechanical ventilation often restores gas exchange promptly, resulting in shorter durations of ventilation. We believe that AAA can occur in children and can lead to respiratory failure that requires mechanical ventilation. Furthermore, children with rapid-onset respiratory failure that requires intubation in the emergency department (ED) are more likely to have AAA and a shorter duration of mechanical ventilation than those intubated in the pediatric intensive care unit (PICU). Methods. An 11-year retrospective chart review (1991-2002) was conducted of all children who were aged 2 through 18 years and had the primary diagnosis of status asthmaticus and required mechanical ventilation. Results. During the study period, 33 (11.4%) of 290 PICU admissions for status asthmaticus required mechanical ventilation. Thirteen children presented with rapid respiratory failure en route, on arrival, or within 30 minutes of arrival to the ED versus 20 children who progressed to respiratory failure later in their ED course or in the PICU. Mean duration of mechanical ventilation was significantly shorter in the children who presented with rapid respiratory failure versus those with progressive respiratory failure (29 ± 43 hours vs 88 ± 72 hours). Children with rapid respiratory failure had greater improvements in ventilation and oxygenation than those with progressive respiratory failure as measured by pre- and postintubation changes in arterial carbon dioxide pressure, arterial oxygen pressure/fraction of inspired oxygen ratio, and alveolar-arterial gradient. According to site of intubation, 23 children required intubation in the ED, whereas 10 were intubated later in the PICU. Mean duration of mechanical ventilation was significantly shorter in the ED group versus the PICU group (42 ± 63 hours vs 118 ± 46 hours). There were significantly greater improvements in ventilation and oxygenation in the ED group versus the PICU group as measured by pre- and postintubation changes in arterial carbon dioxide pressure and arterial oxygen pressure/fraction of inspired oxygen ratio. Conclusions. AAA occurs in children and shares characteristics seen in adult counterparts. Need for early intubation is a marker for AAA and may not represent a failure to maximize preintubation therapies. AAA represents a distinct form of life-threatening asthma and requires additional study in children.

Invasive pneumococcal disease continues to be a major cause of morbidity and mortality among children and adults worldwide. Effective host defence against Streptococcus pneumoniae depends on immunoglobulin G-mediated phagocytosis of the bacteria and it has been shown in vitro that the FcgammaRIIA polymorphism (FcgammaRIIA-R131 vs FcgammaRIIA-H131) determines the capacity of immunoglobulin G2-mediated phagocytosis via this receptor. In this study, we evaluated FcgammaRIIA polymorphisms in children with pneumococcal sepsis and a number of control groups in order to investigate a possible association of FcgammaRIIA genotypes with Streptococcus pneumoniae infection. The distribution of the genotypes differed in these populations. The frequency of homozygosity for FcgammaRIIA-R/R131 in the patients was significantly higher than that in the healthy random donor population (43% vs 21%, P<0.05). The frequencies of FcgammaRIIA-H/H131 were similar among all groups of individuals, while the incidence of the heterozygous FcgammaRIIA-R/H131 was lower (35% vs 52%, P<0.05). Thus, it appears that the FcgammaRIIA-H131 polymorphic form, even in the heterozygous form, may be protective for pneumococcal sepsis and children with FcgammaRIIA-R/R131 genotype could be more at risk of infection with invasive Streptococcus pneumoniae.

Highly active antiretroviral therapy (HAART) has suppressed viral replication and facilitated normalization of T cell subsets, resulting in restoration of immunity against opportunistic pathogens. Induction of full immune restoration in chronically infected individuals, including HIV-specific helper T cell responses, is considered a priority, particularly if immunological control of HIV is to be achieved. Regimens containing dual protease inhibitors (PIs) have provided greater suppression of viremia than single-PI regimens. We therefore conducted a prospective analysis of factors associated with immune restoration after 3 years of therapy in two cohorts of acutely and chronically HIV-infected patients, comparing dual- versus single-PI regimens. Earlier and more durable returns of p24-specific proliferation were demonstrated in patients receiving dual-PI compared with single-PI regimens. Individuals with restored p24 responses had larger reductions in total HIV-specific cytotoxic T lymphocytes (CTLs) associated with stronger viral suppression, but Gag-specific CTLs remained higher, demonstrating that Gag-specific helper T cell responses were a critical component of functional immune restoration. On examination of clinical factors associated with immune restoration, we demonstrated that decreasing activation of CD8+ T cells (%CD8+ CD38+) and increasing proportions of CD4+ T cells were independently associated with restoration of p24 responses. Minimal immune activation, resulting from maximal suppression of viral replication, was required for long-term restoration and maintenance of Gag-specific T cell responses. This study uniquely demonstrates that dual-PI regimens are superior in achieving these levels of virological control and immune restoration in both chronic and acute infection, compared with single-PI or non-PI regimens.