Strategies for screening blood donors to source convalescent H1N1v plasma for intervention therapy.

BACKGROUND AND OBJECTIVES: During the 1918, pandemic blood components were successfully used to treat severe influenza pneumonia. A Proof of Principle trial investigating the clinical benefit of convalescent plasma was proposed in the 2009 H1N1v epidemic with the aim of screening donors for high titre antibody in order to stockpile plasma packs to be used for treatment for severe pneumonia. MATERIALS AND METHODS: Serum samples were collected from donors. IgG antibody capture format enzyme-linked immunoassays using recombinant proteins (GACELISAs) were compared with microneutralization (MN) and haemagglutination inhibition (HAI). The influence of age and history of influenza-like illness (ILI) on the detection of high titre antibody was examined. RESULTS: 1598 unselected donor sera collected in October and December 2009 were tested by HAI. The HAI and demographic data defined a possible strategy for selective donor screening. One of the GACELISAs was highly specific for recent infection but showed lower sensitivity than HAI. CONCLUSIONS: During the 2009 pandemic screening 17- to 30-year-old donors by HAI delivered around 10% with high antibody levels. The ELISA using a short recombinant H1N1v HA detected fewer reactives but was more specific for high titre antibody (≥1:256). Screening strategies are proposed based on using HAI on serum or GACELISA on plasma.

Measles immunity testing: comparison of two measles IgG ELISAs with plaque reduction neutralisation assay.

Two commercial IgG ELISAs, one based on recombinant nucleocapsid antigen and one based on cell culture grown native virus antigens, were evaluated for measles immunity testing by comparison with plaque reduction neutralisation test (PRNT). Qualitative results of the two ELISAs showed 92% agreement with those of PRNT. The sensitivity of the two ELISAs was 89.6%. False negative ELISA results were obtained in 10% of sera, mainly sera containing low levels of neutralising antibody. The specificity of both ELISAs was 100%. Measles IgG ELISAs perform adequately for immunity testing, correctly identifying seronegative individuals for vaccination.

Detection of rubella antibody using an optical immunosensor.

Since the first biosensor was reported in 1962 different sensors have been developed in different areas; their attraction being that they hold out the possibility of a rapid test which can specifically detect the analyte, without the necessity for additional reagents. Immunosensors make use of antibodies and can be extremely specific if the appropriate monoclonal antibodies are used. We report on the development of an optical immunosensor used for the detection of rubella antibody in serum, plasma and whole blood. The assay time is less than 10 min and requires no accurate measurement of the sample or any additional reagents. The sensitivity is in the region of 30 IU/ml; with a correlation of 94% with conventional assays.

Laboratory methods for assessing vaccine potency retained in aerosol outputs from nebulizers: application to World Health Organization measles aerosol project.

BACKGROUND: Laboratory methods for measuring vaccine potency of nebulized aerosol are required to support clinical trials of measles aerosol vaccination. METHODS: Measles vaccine containing the Edmonston Zagreb virus strain was reconstituted in sodium fluoride as tracer and nebulized from three devices. Emitted aerosol was collected using an impinger. Aliquots were removed from the impinger chamber for vaccine virus plaque assay and for fluoride measurement to determine aerosol output. RESULTS: Vaccine potency retention results were adjusted to take into account the effect of aerosol output on estimates. Adjusted potency of nebulized vaccine ranged from 88% to 102%. CONCLUSIONS: New laboratory methods to measure aerosol vaccine potency retention were reliable and accurate. The results demonstrated that Edmonston Zagreb vaccine remains robust during aerosolisation and imply that this is a viable candidate for further evaluation in the measles aerosol project.

Impaired polymorphonuclear leucocyte chemotaxis after influenza virus infection.

Polymorphonuclear leucocyte function was assessed in 13 patients with influenza by measuring phagocytosis of staphylococci and chemotaxis. Significant impairment of chemotaxis was shown. Subsequeuntly polymorph chemotaxis was found to be impaired in a group of volunteers infected with virus recombinants of A/New Jersey/8/76 but not in volunteers infected with a virus recombinant of A/Victoria/3/75. These results accord well with the in vitro effects of certain influenza viruses on polymorph function and suggest that interference with polymorph function may predispose to bacterial pneumonia after clinical influenza.

Possible virus in schizophrenia and some neurological disorders.

Cerebrospinal fluid from 13 of 38 patients with schizophrenia had a cytopathic effect in cultures of MRC5 cells. The cytopathic agent passed a 100 nm but not a 50 nm filter and was unaffected by heat at 56 degrees C for 30 min, treatment with chloroform, or the presence in cultures of bromodeoxyuridine. The agent could not be propagated serially in a satisfactory manner but its properties were those of a virus. A similar cytopathic effect was induced by cerebrospinal fluid from 8 of 11 patients with serious or chronic nervous system disease but only 1 of 25 patients with surgical or general medical conditions.

Influenza viruses and staphylococci in vitro: some interactions with polymorphonuclear leucocytes and epithelial cells.

Bacterial infection contributes substantially to the morbidity and mortality of human influenza. In vitro experiments were performed to test two hypotheses regarding a possible relationship between the virus and bacterial infection. Firstly, maintenance media from tissue and organ cultures infected with influenza virus were tested for the presence of staphylococcal growth-promoting factors; no evidence for these was found. Secondly, we looked for a virus effect on polymorphonuclear leucocyte function. We found that human leucocytes purified from venous blood and exposed to influenza virus responded normally to stimulation of hexose monophosphate shunt activity and chemiluminescence. However, their responses in tests of phagocytic function and of chemotaxis were inhibited. By various criteria this effect was specific to the virus and could be obtained even when only a few virus particles were present per leucocyte. We propose that this is a mechanism by which influenza virus could enhance susceptibility to bacterial infection in the lung.

An investigation of the effects of intracerebral injection in the marmoset of cytopathic cerebrospinal fluid from patients with schizophrenia or neurological disease.

In experiments designed to investigate transmission, cerebrospinal fluid (CSF) from patients with schizophrenia and neurological disease (huntington's chorea and multiple sclerosis) which had been found to induce cytopathic effects in human embryonic fibroblast cell culture was injected intracerebrally into mice, hamsters and marmosets (small New World primates). No evidence was obtained of transmission to mice or hamsters. A total of 15 marmosets (Callithrix jacchus) was injected intracerebrally with CSF [8 with samples from 4 patients with schizophrenia. 3 with samples from patients with neurological disease (2 with Huntington's chorea and 1 with multiple sclerosis) and 4 with samples from 3 patients without neurological or psychiatric disease] and was observed over a period of 2 1/2 years. Analysis of variance on data obtained from behavioral observations averaged over 6-month periods revealed that animals injected with CSF from patients with schizophrenia and neurological disease became progressively more inactive when compared with animals injected with CSF from control patients. The change detected by behavioural observation was confirmed as a difference 2 and 2 1/2 years after injection by automated activity monitoring. There was an incidence of reproductive anomalies (including two occipital encephalocoeles) in the females in the experimental group, but the numbers are too small to draw firm conclusions from this observation. Many reported differences in biological samples from schizophrenic patients and normal controls have subsequently been found to be due to factors unrelated to the disease state. This may prove to be the case with the changes observed in this experiment. Nevertheless, the fact that marmosets injected with CSF from patients suffering from neuropsychiatric disease, including schizophrenia, subsequently differed in their behaviour from those injected with control CSF warrants further investigation.

Characteristics of patients with schizophrenia or neurological disorder and virus-like agent in cerebrospinal fluid.

A virus-like agent (V.L.A.) with a cytopathic effect on cultured cells was found in the cerebrospinal fluid of 18 of 47 patients with schizophrenia, of whom 10 had nuclear schizophrenic symptoms. In most patients with V.L.A., blood and C.S.F. protein concentrations were normal. Patients with and without V.L.A. had similar clinical characteristics but serum IgA levels were higher in those with V.L.A. V.L.A. was also detected in the C.S.F. of 8 of 11 patients with serious or chronic neurological disease (Huntington's chorea, multiple sclerosis, and unexplained alterations of consciousness).

Role of viruses in febrile convulsions.

A disseminated viral illness was demonstrated by isolating a virus from the CSF, blood or urine in 27% of 73 children who were admitted to hospital after a first febrile convulsion. However, a viral aetiology could be implicated for 86% of the children after combining results of tissue culture, electron microscopy, mouse inoculation, complement fixation tests, and interferon assay. Parallel bacterial cultures showed a possible pathogen in 29% of children, but in only 4% was the pathogen isolated from the CSF, blood, or urine. No correlation was found between the nature of the pathogen (or evidence of its dissemination) and the severity of the convulsion, degree of fever, CSF protein, CSF white cells, or the WBC. The results suggest that a febrile convulsion could be a response to invasion of the blood stream or central nervous system by a micro-organism which is usually a virus. Invasion may be of such brief duration that successful isolation of the virus from the blood, CSF, or urine in not more commonly achieved.

A year's experience of the rotavirus syndrome and its association with respiratory illness.

In a hospital study rotavirus was identified in 51% of 152 children with diarrhoea. These patients showed a clinical pattern that was distinct from patients in whom the diarrhoea was associated with bacteria, other viruses, or no pathogens. A respiratory illness was described in 66% of rotavirus patients and usually preceded the gastrointestinal symptoms. Vomiting lasted between one and 3 days and was curtailed by substituting the normal diet with clear fluids. Watery diarrhoes continued for 4 or 5 days, even when rehydration was by the intravenous rather than the oral route. Prolonged diarrhoea was rare. Most children infected with rotavirus were under 2 years of age, but dehydration was most severe in infants aged between 12 and 18 months. A clinician can thus recognise the rotavirus syndrome and expect spontaneous recovery if adequate rehydration is maintained for a critical few days.