Causes of encephalitis and differences in their clinical presentations in England: a multicentre, population-based prospective study.

BACKGROUND: Encephalitis has many causes, but for most patients the cause is unknown. We aimed to establish the cause and identify the clinical differences between causes in patients with encephalitis in England. METHODS: Patients of all ages and with symptoms suggestive of encephalitis were actively recruited for 2 years (staged start between October, 2005, and November, 2006) from 24 hospitals by clinical staff. Systematic laboratory testing included PCR and antibody assays for all commonly recognised causes of infectious encephalitis, investigation for less commonly recognised causes in immunocompromised patients, and testing for travel-related causes if indicated. We also tested for non-infectious causes for acute encephalitis including autoimmunity. A multidisciplinary expert team reviewed clinical presentation and hospital tests and directed further investigations. Patients were followed up for 6 months after discharge from hospital. FINDINGS: We identified 203 patients with encephalitis. Median age was 30 years (range 0-87). 86 patients (42%, 95% CI 35-49) had infectious causes, including 38 (19%, 14-25) herpes simplex virus, ten (5%, 2-9) varicella zoster virus, and ten (5%, 2-9) Mycobacterium tuberculosis; 75 (37%, 30-44) had unknown causes. 42 patients (21%, 15-27) had acute immune-mediated encephalitis. 24 patients (12%, 8-17) died, with higher case fatality for infections from M tuberculosis (three patients; 30%, 7-65) and varicella zoster virus (two patients; 20%, 2-56). The 16 patients with antibody-associated encephalitis had the worst outcome of all groups-nine (56%, 30-80) either died or had severe disabilities. Patients who died were more likely to be immunocompromised than were those who survived (OR = 3·44). INTERPRETATION: Early diagnosis of encephalitis is crucial to ensure that the right treatment is given on time. Extensive testing substantially reduced the proportion with unknown cause, but the proportion of cases with unknown cause was higher than that for any specific identified cause. FUNDING: The Policy Research Programme, Department of Health, UK.

Prevalence of disease related prion protein in anonymous tonsil specimens in Britain: cross sectional opportunistic survey.

OBJECTIVE: To establish with improved accuracy the prevalence of disease related prion protein (PrP(CJD)) in the population of Britain and thereby guide a proportionate public health response to limit the threat of healthcare associated transmission of variant Creutzfeldt-Jakob disease (vCJD). DESIGN: Cross sectional opportunistic survey. Study samples Anonymised tonsil pairs removed at elective tonsillectomy throughout England and Scotland. SETTING: National anonymous tissue archive for England and Scotland. MAIN OUTCOME MEASURE: Presence of PrP(CJD) determined by using two enzyme immunoassays based on different analytical principles, with further investigation by immunohistochemistry or immunoblotting of any samples reactive in either assay. RESULTS: Testing of 63 007 samples was completed by the end of September 2008. Of these, 12 753 were from the birth cohort in which most vCJD cases have arisen (1961-85) and 19 908 were from the 1986-95 cohort that would have been also exposed to bovine spongiform encephalopathy through infected meat or meat products. None of the samples tested was unequivocally reactive in both enzyme immunoassays. Only two samples were reactive in one or other enzyme immunoassay and equivocal in the other, and nine samples were equivocally reactive in both enzyme immunoassays. Two hundred and seventy six samples were initially reactive in one or other enzyme immunoassay; the repeat reactivity rate was 15% or less, depending on the enzyme immunoassay and cut-off definition. None of the samples (including all the 276 initially reactive in enzyme immunoassay) that were investigated by immunohistochemistry or immunoblotting was positive for the presence of PrP(CJD). CONCLUSIONS: The observed prevalence of PrP(CJD) in tonsils from the 1961-95 combined birth cohort was 0/32 661 with a 95% confidence interval of 0 to 113 per million. In the 1961-85 cohort, the prevalence of zero with a 95% confidence interval of 0 to 289 per million was lower than, but still consistent with, a previous survey of appendix tissue that showed a prevalence of 292 per million with a 95% confidence interval of 60 to 853 per million. Continuing to archive and test tonsil specimens, especially in older birth cohorts, and other complementary large scale anonymous tissue surveys, particularly of post-mortem tissues, will further refine the calculated prevalence of PrP(CJD).

Poly(ADP-ribose) polymerase-1 (Parp-1)-deficient mice demonstrate abnormal antibody responses.

Poly(ADP-ribosylation) of acceptor proteins is an epigenetic modification involved in DNA strand break repair, recombination and transcription. Here we provide evidence for the involvement of poly(ADP-ribose) polymerase-1 (Parp-1) in antibody responses. Parp-1(-/-) mice had increased numbers of T cells and normal numbers of total B cells. Marginal zone B cells were mildly reduced in number, and numbers of follicular B cells were preserved. There were abnormal levels of basal immunoglobulins, with reduced levels of immunoglobulin G2a (IgG2a) and increased levels of IgA and IgG2b. Analysis of specific antibody responses showed that T cell-independent responses were normal but T cell-dependent responses were markedly reduced. Germinal centres were normal in size and number. In vitro purified B cells from Parp-1(-/-) mice proliferated normally and showed normal IgM secretion, decreased switching to IgG2a but increased IgA secretion. Collectively our results demonstrate that Parp-1 has essential roles in normal T cell-dependent antibody responses and the regulation of isotype expression. We speculate that Parp-1 forms a component of the protein complex involved in resolving the DNA double-strand breaks that occur during class switch recombination.

Virus discovery by sequence-independent genome amplification.

Genome sequences from several blood borne and respiratory viruses have recently been recovered directly from clinical specimens by variants of a technique known as sequence-independent single primer amplification. This and related methods are increasingly being used to search for the causes of diseases of presumed infectious aetiology, but for which no agent has yet been found. Other methods that do not require prior knowledge of the genome sequence of any virus that may be present in the patient specimen include whole genome amplification, random PCR and subtractive hybridisation and differential display. This review considers the development and application of these techniques.

Nocodazole, a microtubule de-polymerising agent, induces apoptosis of chronic lymphocytic leukaemia cells associated with changes in Bcl-2 phosphorylation and expression.

Microtubule active drugs are used in the treatment of malignancies and their mechanism of action in cycling cells is to produce mitotic arrest followed by apoptosis. In this study, we investigate in detail the specificity and mechanism by which a microtubule de-polymerising agent, nocodazole, induces apoptosis in non-cyclingm, i.e. G(0)/G(1), chronic lymphocytic leukaemia (CLL) B-cells. The majority of cases of CLL are sensitive (IC(50)

Isolates of Pneumocystis jirovecii from Harare show high genotypic similarity to isolates from London at the superoxide dismutase locus.

Pneumocystis jirovecii is the cause of Pneumocystis pneumonia (PCP) in humans. Isolates of P. jirovecii obtained from patients in Harare, Zimbabwe were genotyped at the superoxide dismutase locus. High genotypic similarity to isolates of P. jirovecii obtained from patients in London, UK was observed. These data provide additional support for the hypothesis that P. jirovecii is genetically indistinguishable in isolates from geographically diverse locations.

Alpha6-integrin is expressed on germinal centre B cells and modifies growth of a B-cell line.

The production of high-affinity antibodies requires diversification of the antibody repertoire by somatic hypermutation followed by selection of those B cells bearing the highest affinity antibodies. Whilst many surface molecules that mediate the cell-cell interactions required for germinal centre formation have been identified, little is known of the importance of interactions with components of the extracellular matrix, i.e. fibronectin, collagen and laminin. We demonstrate that the laminin-binding alpha6-integrin is expressed on germinal centre B cells and is induced during the in vitro activation of naïve splenic B cells. A laminin network is demonstrated within the germinal centre. Analysis of an alpha6-integrin-expressing mouse B-cell line, A20, demonstrates that this molecule is essential for binding to laminin, and that blocking by anti-alpha6-integrin immunoglobulin causes loss of adhesion associated with an increase in proliferation. There is no correlation with changes in BCL-6 or Blimp-1 expression, suggesting that alpha6-integrin does not play a role in differentiation.

Genotypes of Pneumocystis jiroveci isolates obtained in Harare, Zimbabwe, and London, United Kingdom.

Isolates of Pneumocystis jiroveci from sulfa-exposed and nonexposed patients from London, United Kingdom, and Harare, Zimbabwe, were genotyped. At the dihydropteroate synthase (DHPS) locus, there was evidence of selection pressure from sulfa drug exposure, and reversal of DHPS genotype ratios occurred when selection pressure was absent or was removed.

Limited asymptomatic carriage of Pneumocystis jiroveci in human immunodeficiency virus-infected patients.

Forty-seven bronchoalveolar lavage fluid samples from 16 human immunodeficiency virus (HIV)-infected patients were used to test the latency model of Pneumocystis infection in the human host. Identification of DNA sequence polymorphisms at 4 independent loci were used to genotype Pneumocystis jiroveci from the 35 samples that contained detectable P. jiroveci DNA. Eighteen of those 35 samples came from patients who did not have Pneumocystis pneumonia (PCP) and had confirmed alternative diagnoses. Seven patients had asymptomatic carriage of P. jiroveci over periods of < or = 9.5 months after an episode of PCP, and in all 7 cases, a change in genotype from that in the original episode of PCP was observed. The absence of P. jiroveci DNA in one-fourth of the 47 samples and the observed changes in genotype during asymptomatic carriage do not support the latency model of infection. Asymptomatic carriage in HIV-infected patients may play a role in transmission of P. jiroveci and may even supply a reservoir for future infections.

Probable mother-to-infant transmission of Pneumocystis carinii f. sp. hominis infection.

A mother and her 4.5-week-old infant had Pneumocystis carinii pneumonia contemporaneously. Genotyping of P. carinii f. sp. hominis DNA at three independent loci showed the same genotype in samples from mother and infant. These data suggest transmission of P. carinii organisms from the mother to her infant.