Health and nutrition claims for infant formula: international cross sectional survey

OBJECTIVES

To review available health and nutrition claims for infant formula products in multiple countries and to evaluate the validity of the evidence used for substantiation of claims.

DESIGN

International cross sectional survey.

SETTING

Public facing and healthcare professional facing company owned or company managed formula industry websites providing information about products marketed for healthy infants delivered at full term in 15 countries: Australia, Canada, Germany, India, Italy, Japan, Nigeria, Norway, Pakistan, Russia, Saudi Arabia, South Africa, Spain, the United Kingdom, and the United States in 2020-22.

MAIN OUTCOME MEASURES

Number and type of claims made for each product and ingredient. References cited were reviewed and risk of bias was assessed for registered clinical trials using the Cochrane risk of bias tool, and for systematic reviews using the Risk Of Bias in Systematic reviews tool.

RESULTS

757 infant formula products were identified, each with a median of two claims (range from 1 (Australia) to 4 (US)), and 31 types of claims across all products. Of 608 products with ≥1 claims, the most common claim types were "helps/supports development of brain and/or eyes and/or nervous system" (323 (53%) products, 13 ingredients), "strengthens/supports a healthy immune system" (239 (39%) products, 12 ingredients), and "helps/supports growth and development" (224 (37%) products, 20 ingredients). 41 groups of ingredients were associated with ≥1claims, but many claims were made without reference to a specific ingredient (307 (50%) products). The most common groups of ingredients cited in claims were long chain polyunsaturated fatty acids (278 (46%) products, 9 different claims); prebiotics, probiotics, or synbiotics (225 (37%) products, 19 claims); and hydrolysed protein (120 (20%) products, 9 claims). 161/608 (26%) products with ≥1 claims provided a scientific reference to support the claim-266 unique references were cited for 24 different claim types for 161 products. The reference types most frequently cited were clinical trials (50%, 134/266) and reviews (20%, 52/266). 28% (38/134) of referenced clinical trials were registered, 14% (19/134) prospectively. 58 claims referred to 32 registered clinical trials, of which 51 claims (27 trials) related to a randomised comparison. 46 of 51 claims (90%) referenced registered clinical trial outcomes at high risk of bias, and all cited systematic reviews and pooled analyses, carried a high risk of bias.

CONCLUSIONS

Most infant formula products had at least one health and nutrition claim. Multiple ingredients were claimed to achieve similar health or nutrition effects, multiple claims were made for the same ingredient type, most products did not provide scientific references to support claims, and referenced claims were not supported by robust clinical trial evidence.

Variability in indigenous Pakistani tomato lines and worldwide reference collection for Tomato Mosaic Virus (ToMV) and Tomato Yellow Leaf Curl Virus (TYLCV) infection

Local and exotic germplasm of tomato remains a major source for genetic improvement. Assessment of such lines for biotic stresses particularly viral diseases are the most important criteria for selection in Pakistan, where Tomato Yellow Leaf Curl Virus (TYLCV) and Tomato Mosaic Virus (ToMV) are the major diseases/viruses. A set of 40 accessions (including indigenous Pakistani lines and exotic germplasm from Europe, the United States, and Asia) were evaluated for their resistance/infection response to ToMV with artificial inoculation under greenhouse conditions. Infection response was quantified through disease scoring and DAS-ELISA test (for ToMV). A subset of 24 lines, was further screened for TYLCV using disease scoring and TAS-ELISA. The tested lines showed significant variability for resistance to ToMV. Only one accession (Acc-17878) was resistant to the ToMV whereas seven accessions i.e. Acc-17890, AVR-261, CLN-312, AVR-321, EUR-333, CLN-352, and CLN-362 expressed resistance to TYLCV. Correlation between phenotypic evaluation was confirmed by the ELISA results in both diseases, although both tools complemented to assess the viral infection status. In future, tomato breeding programs must consider breeding for ToMV and TYLCV resistance (using identified germplasm in our study) so as to deliver virus resistant tomato varieties.

IL-6 and other biomarkers as predictors of severity in COVID-19

OBJECTIVE

Cytokine release syndrome is suggested to be the most important mechanism triggering acute respiratory distress syndrome and end organ damage in COVID-19. The severity of disease may be measured by different biomarkers.

METHODS

We studied markers of inflammation and coagulation as recorded in 29 patients on admission to the hospital in order to identify markers of severe COVID-19 and need of ICU.

RESULTS

Patients who were eventually admitted to ICU displayed significantly higher serum levels of interleukin-6 (IL-6), C-reactive protein (CRP), and procalcitonin. No statistical differences were found between the groups in median levels of lymphocytes, D-dimer or ferritin.

CONCLUSIONS

IL-6 and CRP were the strongest predictors of severity in hospitalized patients with COVID-19.

Interference between respiratory syncytial virus and rhinovirus in respiratory tract infections in children

An acute viral respiratory tract infection might prevent infections by other viruses because of the antiviral innate immune response. However, with the use of PCR methods, simultaneous detection of two or more respiratory viruses is frequent. We analysed the effect of respiratory syncytial virus (RSV) infection on the occurrence of simultaneous rhinovirus (RV) infection in children within a birth cohort study setting. We used PCR for virus detection in nasal swabs collected from children with an acute respiratory tract infection at the age of 0-24 months and from healthy control children, who were matched for age and date of sample collection. Of 226 children with RSV infections, 18 (8.0%) had co-infections with RV, whereas RV was detected in 31 (14%) of 226 control children (p 0.049 by chi-square test). Adjustment for sex, number of siblings and socio-economic status strengthened the negative association between RSV and RV (OR 0.46, 95% CI 0.24-0.90; p 0.02). The median durations of symptoms (cough, rhinorrhoea, or fever) were 11 days in children with single RSV infections and 14 days in children with RSV-RV co-infections (p 0.02). Our results suggest that the presence of RSV reduces the probability of RV infection, but that, if a co-infection occurs, both viruses cause clinical symptoms.

Distinct regulation of tonsillar immune response in virus infection

Background

The relationships between tonsillar immune responses, and viral infection and allergy are incompletely known.

Objective

To study intratonsillar/nasopharyngeal virus detections and in vivo expressions of T‐cell‐ and innate immune response‐specific cytokines, transcription factors, and type I/II/III interferons in human tonsils.

Methods

Palatine tonsil samples were obtained from 143 elective tonsillectomy patients. Adenovirus, bocavirus‐1, coronavirus, enteroviruses, influenza virus, metapneumovirus, parainfluenza virus, rhinovirus, and respiratory syncytial virus were detected using PCR. The mRNA expression levels of IFN‐α, IFN‐β, IFN‐γ, IL‐10, IL‐13, IL‐17, IL‐28, IL‐29, IL‐37, TGF‐β, FOXP3, GATA3, RORC2, and Tbet were directly analyzed by quantitative RT‐PCR.

Results

Fifty percentage of subjects reported allergy, 59% had ≥1 nasopharyngeal viruses, and 24% had ≥1 intratonsillar viruses. Tonsillar virus detection showed a strong negative association with age; especially rhinovirus or parainfluenza virus detection showed positive association with IFN‐γ and Tbet expressions. IL‐37 expression was positively associated with atopic dermatitis, whereas IFN‐α, IL‐13, IL‐28, and Tbet expressions were negatively associated with allergic diseases. Network analyses demonstrated strongly polarized clusters of immune regulatory (IL‐10, IL‐17, TGF‐β, FOXP3, GATA3, RORC2, Tbet) and antiviral (IFN‐α, IFN‐β, IL‐28, IL‐29) genes. These two clusters became more distinctive in the presence of viral infection or allergy. A negative correlation between antiviral cytokines and IL‐10, IL‐17, IL‐37, FOXP3, and RORC2 was observed only in the presence of viruses, and interestingly, IL‐13 strongly correlated with antiviral cytokines.

Conclusions

Tonsillar cytokine expression is closely related to existing viral infections, age, and allergic illnesses and shows distinct clusters between antiviral and immune regulatory genes.

Genotyping of clinically relevant human adenoviruses by array-in-well hybridization assay

A robust oligonucleotide array-in-well hybridization assay using novel up-converting phosphor reporter technology was applied for genotyping clinically relevant human adenovirus types. A total of 231 adenovirus-positive respiratory, ocular swab, stool and other specimens from 219 patients collected between April 2010 and April 2011 were included in the study. After a real-time PCR amplification targeting the adenovirus hexon gene, the array-in-well assay identified the presence of B03 (n = 122; 57.5% of patients), E04 (29; 13.7%), C02 (21; 9.9%), D37 (14; 6.6%), C01 (12; 5.7%), C05 (5; 2.4%), D19 (4; 1.9%), C06 (2; 0.9%), D08 (1; 0.5%), A31 (1; 0.5%) and F41 (1; 0.5%) genotypes among the clinical sample panel. The typing result was obtained for all specimens that could be amplified (n = 223; 97%), and specificity of the typing was confirmed by sequencing specimens representing each of the different genotypes. No hybridization signal was obtained in adenovirus-negative specimens or specimens with other viruses (n = 30). The array-in-well hybridization assay has great potential as a rapid and multiplex platform for the typing of clinically relevant human adenovirus genotypes in different specimen types.

Virus shedding after human rhinovirus infection in children, adults and patients with hypogammaglobulinaemia

The shedding of human rhinovirus (HRV) after an acute, naturally acquired infection has not been described in detail. We determined the duration of HRV shedding in immunocompetent children and adults, and in patients with primary hypogammaglobulinaemia. Subjects with symptoms of respiratory tract infection, and their household contacts, were screened for HRV by reverse transcription PCR. They were followed by serial, self-collected nasal swab specimens until negative for HRV or infected by another HRV type. We followed 62 HRV infections in 54 subjects. The mean (95% CI) duration of HRV shedding was 11.4 (8.2-14.7) days in children, 10.1 (7.4-12.9) days in adults, and 40.9 (26.4-55.4) days in patients with hypogammaglobulinaemia (p <0.001). The duration of respiratory tract symptoms correlated with the duration of virus shedding (p 0.002). A new infection by another HRV type soon after the first episode was common. We conclude that the shedding times of HRV are relatively short in otherwise healthy individuals. In contrast, prolonged shedding over 28 days is frequent in patients with hypogammaglobulinaemia despite immunoglobulin replacement therapy.

Viruses and bacteria in sputum samples of children with community-acquired pneumonia

Clin Microbiol Infect 2012; 18: 300–307

Abstract

Few comprehensive studies have searched for viruses and bacteria in children with community‐acquired pneumonia (CAP). We identified 76 children hospitalized for pneumonia. Induced sputum samples were analysed for 18 viruses by antigen detection and PCR, and for six bacteria by culture and PCR. Viruses were found in 72% of samples, bacteria in 91%, and both in 66%. Rhinovirus (30%), human bocavirus (18%) and human metapneumovirus (14%) were the most commonly detected viruses. Two viruses were found in 22% of samples and three in 8%. The most common bacteria found were Streptococcus pneumoniae (50%), Haemophilus influenzae (38%), and Moraxella catarrhalis (28%). Rhinovirus–S. pneumoniae was the most commonly found combination of virus and bacterium (16%). All six children with treatment failure had both viruses and bacteria detected in the sputum. Otherwise, we found no special clinical characteristics in those with mixed viral–bacterial detections. With modern molecular diagnostic techniques, there are high rates of both viral and bacterial identification in childhood CAP. The clinical significance of mixed viral–bacterial infections remains unclear, although we found a potential association between them and treatment failure.

Treatment of experimental autoimmune encephalomyelitis in SJL/J mice with a replicative HSV-1 vector expressing interleukin-5

Experimental autoimmune encephalomyelitis (EAE) is an autoimmune inflammation of the central nervous system and is used as the experimental model of multiple sclerosis (MS). The exact mechanism behind the disease is still unknown, but interleukin (IL)-17 expressing T cells are thought to mediate the disease. Toll-like receptors (TLRs) are known to have a role in the innate immune response against pathogens, and several TLRs have also a role in the disease course of EAE. Here, we show that treatment with a herpes simplex virus type 1 vector expressing the Th2 cytokine IL-5 ameliorates EAE and decreases the numbers of infiltrating lymphocytes in the brain. The effect involves downregulation of TLR 2, 3 and 9 mRNA expression and upregulation of type I interferons (IFNs) in brains during onset of disease. The elevated expression of type I IFNs was also observed during recovery.

Allergic sensitization is associated with rhinovirus-, but not other virus-, induced wheezing in children

BACKGROUND

Data on the link between atopy and viral wheeze are limited.

AIM

To evaluate the association between IgE sensitization and viral infection in wheezing children.

METHODS

This is an observational study in hospitalized wheezing children (n = 247; median age 1.6 ; interquartile range 1.1, 2.9). Eighteen respiratory viral infections were studied using all available methods. A specific immunoglobulin E (IgE) sensitization for common food and aeroallergens and other atopy-related variables including total IgE, blood and nasal eosinophils, exhaled nitric oxide, eczema and atopic eczema, parental allergy and asthma, number of wheezing episodes, positive asthma predictive index or asthma and use of inhaled corticosteroid were correlated with specific viral etiology.

RESULTS

Atopy was closely associated with sole rhinovirus etiology (n = 58) but not with sole respiratory syncytial virus, sole enterovirus, sole human bocavirus, sole other virus, mixed viral, or virus negative etiology. The number of sensitizations was particularly associated with sole rhinovirus etiology (odds ratio 4.59; 95% confidence interval 1.78, 11.8; adjusted to age and sex), followed by aeroallergen sensitization (respectively; 4.18; 2.00, 8.72), total IgE level (2.06; 1.32, 3.21), food allergen sensitization (2.02; 1.08, 3.78), and nasal eosinophil count (1.52; 1.08, 2.13).

CONCLUSIONS

According to our data, allergic sensitization is positively linked to rhinovirus-, but not other virus-, associated wheezing and calls attention for studies to test rhinovirus-associated wheezing as a part of asthma risk indices.

Recurrent wheezing after respiratory syncytial virus or non-respiratory syncytial virus bronchiolitis in infancy: a 3-year follow-up

BACKGROUND

Recent studies have suggested that rhinovirus-associated early wheezing is a greater risk factor for development of recurrent wheezing in children than is early wheezing associated with respiratory syncytial virus (RSV). We determined the development of recurrent wheezing in young children within 3 years after hospitalization for RSV or non-RSV bronchiolitis.

METHODS

We identified retrospectively all children <2 years of age who were admitted to Turku University Hospital because of bronchiolitis in the months of August-December during 1988-2001. The primary outcome was recurrent wheezing that required long-term asthma medication. Data on asthma medications of the individual children were derived from the Social Insurance Institution of Finland.

RESULTS

Within the first year after hospitalization, 36 of 217 (16.6%) children with non-RSV bronchiolitis developed recurrent wheezing, compared with five of 199 (2.5%) children with RSV bronchiolitis [relative risk (RR) 6.6; 95% confidence interval (CI) 2.6-16.5]. The rates of recurrent wheezing were significantly increased in the non-RSV group also within 2 years (RR 2.9; 95% CI 1.7-5.1) and 3 years (RR 3.4; 95% CI 2.0-5.7) after hospitalization. The increased risk of recurrent wheezing in children with non-RSV-associated bronchiolitis was observed both in boys and girls at all time points of the 3-year follow-up, and it was not explained by the age difference between the RSV and non-RSV groups or any confounding seasonal factors.

CONCLUSION

Children hospitalized with bronchiolitis caused by other viruses than RSV develop recurrent wheezing at substantially higher rates during a 3-year follow-up period than do children with RSV-induced bronchiolitis.

Induced sputum in the diagnosis of childhood community-acquired pneumonia

BACKGROUND

The usefulness of induced sputum in searching for causative agents of pneumonia in children has not been studied.

METHODS

The study involved 101 children, aged 6 months to 15 years, treated for community-acquired pneumonia at Turku University Hospital (Turku, Finland) from January 2006 to April 2007. Nasopharyngeal aspirate samples were first collected through both nostrils. Sputum production was then induced by inhalation of 5.0% hypertonic saline for 5-10 min and a sputum sample was either aspirated or expectorated. The presence and amount of bacteria and viruses in paired nasopharyngeal aspirate and sputum specimens was analysed and compared using semiquantitative bacterial culture and quantitative PCR techniques.

RESULTS

A good quality sputum specimen was obtained from 76 children. The possible causative agent was found in 90% of cases. Streptococcus pneumoniae (46%) and rhinovirus (29%) were the most common microbes detected. Newly discovered viruses human bocavirus and human metapneumovirus were detected in 18% and 13% of the children, respectively. One-quarter of all bacterial findings were only detected in sputum, and the amount of bacteria in the remainder of the sputum specimens compared with nasopharyngeal aspirate was higher in 14% and equal in 70%. The amount of rhinovirus in sputum was higher than in nasopharyngeal aspirate in 82%.

CONCLUSIONS

Sputum induction provides good quality sputum specimens with high microbiological yield in children with community-acquired pneumonia. Induced sputum analysis can be useful in the microbiological diagnosis of childhood community-acquired pneumonia.

MxA protein assay for optimal monitoring of IFN-beta bioactivity in the treatment of MS patients

OBJECTIVES

Myxovirus resistance protein A (MxA) can be used as a marker of the bioactivity of interferon-beta (IFN-beta) therapy. Two to forty per cent of IFN-beta-treated multiple sclerosis (MS) patients develop IFN-beta-neutralizing antibodies (NAb) with subsequent attenuation of MxA protein induction. The aim of this study was to set up a simple MxA enzyme immunoassay (EIA) for the measurement of MxA protein and to evaluate the EIA test by comparing the results with flow cytometric analysis and the measurement of NAb.

METHODS

total of 51 IFN-beta-treated relapsing-remitting MS (RRMS) patients were tested for MxA protein expression by using both MxA EIA assay and flow cytometric analysis. Thirteen patients were confirmed to be NAb-positive.

RESULTS

The correlation between EIA and flow cytometric analysis was significant with a wider range of measured levels in the EIA. Patients with NAb had low MxA levels, but in some patients, remaining MxA induction could be detected despite NAb.

CONCLUSIONS

The MxA EIA assay seems to be a practical method for large-scale analysis of the bioactivity of IFN-beta treatment.

Understanding the transmission dynamics of respiratory syncytial virus using multiple time series and nested models

The nature and role of re-infection and partial immunity are likely to be important determinants of the transmission dynamics of human respiratory syncytial virus (hRSV). We propose a single model structure that captures four possible host responses to infection and subsequent reinfection: partial susceptibility, altered infection duration, reduced infectiousness and temporary immunity (which might be partial). The magnitude of these responses is determined by four homotopy parameters, and by setting some of these parameters to extreme values we generate a set of eight nested, deterministic transmission models. In order to investigate hRSV transmission dynamics, we applied these models to incidence data from eight international locations. Seasonality is included as cyclic variation in transmission. Parameters associated with the natural history of the infection were assumed to be independent of geographic location, while others, such as those associated with seasonality, were assumed location specific. Models incorporating either of the two extreme assumptions for immunity (none or solid and lifelong) were unable to reproduce the observed dynamics. Model fits with either waning or partial immunity to disease or both were visually comparable. The best fitting structure was a lifelong partial immunity to both disease and infection. Observed patterns were reproduced by stochastic simulations using the parameter values estimated from the deterministic models.

Rotavirus-specific T cell responses and cytokine mRNA expression in children with diabetes-associated autoantibodies and type 1 diabetes

Rotavirus infections have been implicated as a possible trigger of type 1 diabetes. We elucidated this connection by comparing peripheral blood T cell responses to rotavirus between children with newly diagnosed type 1 diabetes (n = 43), healthy children with multiple diabetes-associated autoantibodies (n = 36) and control children carrying human leukocyte antigen (HLA)-conferred susceptibility to type 1 diabetes but without autoantibodies (n = 104). Lymphocyte proliferation assays based on stimulation with an antigen were performed using freshly isolated peripheral blood mononuclear cells (PBMC) and IgG and IgA class rotavirus antibodies were measured using plasma samples collected from the children. The expression of interferon (IFN)-gamma, interleukin (IL)-4, IL-10 and transforming growth factor (TGF)-beta in PBMC was studied with real-time polymerase chain reaction (PCR) in a subgroup of 38 children. No differences were observed in the strength or frequency of positive T cell responses to rotavirus between children with overt diabetes, children with multiple autoantibodies and control children. Children with diabetes-associated autoantibodies had, instead, stronger T cell responses to purified coxsackie B4 virus than control children. Rotavirus-stimulated lymphocytes from autoantibody-positive children produced more IL-4 and phytohaemagglutinin (PHA)-stimulated lymphocytes more IL-4 and IFN-gamma than lymphocytes from control children. PHA-stimulated lymphocytes from children with diabetes also produced more IL-4 and purified protein derivative (PPD)-stimulated lymphocytes less TGF-beta than lymphocytes from autoantibody-negative control children. In conclusion, our lymphocyte proliferation studies did not provide evidence supporting an association between rotavirus infections and the development of type 1 diabetes or diabetes-associated autoantibodies in young children.

High sensitivity measurement of CRP and disease progression in multiple sclerosis

The authors measured serum C-reactive protein (CRP) serially in patients with multiple sclerosis (MS) who participated the PRISMS study using a high-sensitivity technique. CRP values were similar in patients with MS and in healthy controls but higher during MS relapses than in remission (p = 0.010). CRP levels were lower during treatment with high-dose interferon beta 1a than placebo (p = 0.035) and higher during first 12 months of study in patients who progressed by year 4 compared with stable patients (p = 0.007).

The transmission dynamics of groups A and B human respiratory syncytial virus (hRSV) in England & Wales and Finland: seasonality and cross-protection

Human respiratory syncytial virus (hRSV) transmission dynamics are inherently cyclical, and the observed genetic diversity (between groups A and B) also appears to have a repeating pattern. A key unknown is the extent to which genetic variants interact immunologically, and thus impact on epidemiology. We developed a novel mathematical model for hRSV transmission including seasonal forcing of incidence and temporary intra- and inter-group partial immunity. Simultaneous model fits to data from two locations (England & Wales, UK, and Turku, Finland) successfully reproduced the contrasting infection dynamics and group A/B dominance patterns. Parameter estimates are consistent with direct estimates. Differences in the magnitude and seasonal variation in contact rate between the two populations alone could account for the variation in dynamics between these populations. The A/B group dominance patterns are explained by reductions in susceptibility to and infectiousness of secondary homologous and heterologous infections. The consequences of the observed dynamic complexity are discussed.

In vitro kinetics of allergen- and microbe-induced IL-4 and IFN-gamma mRNA expression in PBMC of pollen-allergic patients

BACKGROUND

According to a hypothesis allergens induce Th2 responses in allergic patients, and microbes induce Th1 responses. We studied the kinetics of in vitro allergen-, tuberculin (PPD)- and tetanus toxin (TT)-induced IFN-gamma and IL-4 mRNA expression in peripheral blood mononuclear cell (PBMC) cultures of pollen-allergic patients and healthy controls.

METHODS

PBMC of 10 birch or timothy pollen-allergic patients and of 13 healthy controls were stimulated in vitro with allergen (birch or timothy), PPD or TT. Pellets and supernatants were collected at 24, 48, 72 and 96 h after stimulation. IFN-gamma and IL-4 production was measured by enzyme linked immunosorbent assay and mRNA expression using RT-PCR and time-resolved fluorometry.

RESULTS

Allergen induced IFN-gamma production and mRNA expression in PBMC more in allergic patients than in healthy controls. Also allergen induced IL-4 mRNA expression more in allergic patients than in healthy controls. PPD induced IFN-gamma mRNA expression both in allergic patients and healthy controls, whereas IFN-gamma production was induced only in healthy controls and IL-4 was not induced at all. TT induced IFN-gamma mRNA expression in both groups, IFN-gamma production in allergic patients, and IL-4 mRNA expression in both allergic patients and healthy controls.

CONCLUSIONS

In vitro stimulation with allergen induced both IFN-gamma and IL-4 mRNA expression of PBMC in allergic patients. These observations challenge the clearcut division of microbe-specific Th1 and allergen-specific Th2 responses in peripheral blood.

Salivary defense factors in herpes simplex virus infection

Saliva may contribute to a lowering of the infectious herpes simplex virus (HSV) dose during transmission and consequently abrogate infection or lead to decreased reactivation. To test this hypothesis, we assayed saliva for innate defense factors, immunoglobulin content, and the capacity to interfere with HSV infection. Serum or salivary anti-HSV IgG levels did not correlate with control of recurrent labial herpes (RLH) and were significantly higher in subjects with RLH compared with asymptomatic seropositive subjects. Although no differences in levels or output rate of innate defense factors between the groups were observed, the salivary neutralizing activity correlated with lactoferrin and hypothiocyanite concentrations in the asymptomatic seropositive group. Our results suggest that saliva contains factors, in addition to anti-HSV immunoglobulins, that neutralize HSV and may indirectly contribute to the control of RLH.

Time-resolved fluorometry PCR assay for rapid detection of herpes simplex virus in cerebrospinal fluid

We have introduced a time-resolved fluorometry (TRF)-based microwell hybridization assay for PCR products in detection of herpes simplex virus (HSV) in cerebrospinal fluid (CSF) specimens. TRF is a sensitive nonradioactive detection technique which involves the use of lanthanide chelates as fluorescent labels. We used PCR primers from the glycoprotein D genes of HSV type 1 (HSV-1) and HSV-2. The biotinylated PCR products were collected on streptavidin-coated microtitration wells and hybridized with short oligonucleotide probes, europium labeled for HSV-1 and samarium labeled for HSV-2. The TRF results were obtained as counts per second and as signal-to-noise (S/N) ratios. The sensitivity of the assay was 0.1 infectious units (PFU) of HSV in CSF specimens, and the S/N values increased with the virus amount, up to 68.5 for 10(3) PFU of HSV-1 and to 58.5 for 10(3) PFU of HSV-2, allowing semiquantitation of HSV in CSF. The primers and probes recognized all the studied 48 HSV wild-type samples, with S/N ratios of 12.4 to 190 (HSV-1) and 5.1 to 248 (HSV-2). We tested CSF specimens, 100 for each HSV type, which were HSV PCR negative by Southern blot and 22 CSF specimens which were HSV-1 or -2 PCR blot positive. In the TRF test, the mean S/N ratio for the HSV-1-negative CSF was 1.37 (standard deviation [SD] = 0.513) and for the HSV-2-negative CSF it was 1.03 (SD = 0.098). The HSV-1 blot-positive CSF yielded S/N ratios of 3.6 to 85.9, and the HSV-2 blot-positive CSF yielded ratios from 1.9 to 13. Using the mean S/N ratio for negative CSF specimens + 3 SD as the cutoff yielded all the previously HSV-positive specimens as TRF positive. The TRF PCR assay for HSV in CSF specimens is a rapid and sensitive method, improves interpretation of PCR results, and is well suited for automation.

Intranasal fluticasone propionate does not prevent acute otitis media during viral upper respiratory infection in children

BACKGROUND

Acute otitis media (AOM) is the most common complication of a viral upper respiratory infection (URI) in children. The virus-induced host inflammatory response in the nasopharynx plays a key role in the pathogenesis of AOM. Suppression of this inflammatory process might prevent the development of AOM as a complication.

OBJECTIVE

We sought to assess the effect of intranasally administered fluticasone propionate on prevention of AOM during a viral respiratory infection.

METHODS

A total of 210 children (mean age, 2.1 years; range, 0.7-3.9 years) with normal middle ear status and URI of 48 hours' duration or less were randomly allocated to receive either fluticasone (100 microg twice daily) or placebo for 7 days. The specific viral cause of the infection was determined from nasopharyngeal aspirates obtained at the first visit. The children were re-examined at the end of the 7-day medication period.

RESULTS

In the fluticasone group AOM developed in 40 (38.1%) of 105 children compared with 29 (28.2%) of 103 children receiving placebo (P =.13). The viral cause of the respiratory infection was determined in 167 (86.1%) of 194 children from whom a nasopharyngeal aspirate was obtained. In children with rhinovirus infection, AOM developed significantly more often in the fluticasone group (45.7%) than in the placebo group (14.7%, P =.005).

CONCLUSION

Intranasally administered fluticasone does not prevent the development of AOM during URI but may increase the incidence of AOM during rhinovirus infection.

Etiology of community-acquired pneumonia in 254 hospitalized children

BACKGROUND

Childhood community-acquired pneumonia is a common illness, but there have been relatively few comprehensive studies of the viral and bacterial etiology in developed countries. The aim of the present investigation was to determine the etiology of community-acquired pneumonia in hospitalized children by several laboratory methods.

METHODS

In a 3-year prospective study a nasopharyngeal aspirate for viral studies and acute and convalescent serum samples for viral and bacterial serology were taken from 254 children with symptoms of acute infection and infiltrates compatible with pneumonia in the chest radiograph. The role of 17 microbes was investigated.

RESULTS

A potential causative agent was detected in 215 (85%) of the 254 patients. Sixty-two percent of the patients had viral infection, 53% had bacterial infection and 30% had evidence of concomitant viral-bacterial infection. Streptococcus pneumoniae (37%), respiratory syncytial virus (29%) and rhinovirus (24%) were the most common agents associated with community-acquired pneumonia. Only one patient had a positive blood culture (S. pneumoniae) of 125 cultured. A dual viral infection was detected in 35 patients, and a dual bacterial infection was detected in 19 patients.

CONCLUSIONS

The possible causative agent of childhood community-acquired pneumonia can be detected in most cases. Further studies are warranted to determine what etiologic investigations would aid in the management of pneumonia. With effective immunization for S. pneumoniae and respiratory syncytial virus infections, more than one-half of the pneumonia cases in this study could have been prevented.

Simultaneous detection of IFN-gamma and IL-4 mRNAs using RT-PCR and time-resolved fluorometry

Time-resolved fluorometry was applied in the detection of RT-PCR amplified mRNAs for the Th1 and Th2 cell-derived cytokines interferon gamma (IFN-gamma) and interleukin (IL-)4, respectively. RNA stimulated cells was reverse transcribed and the cDNAs for the cytokine mRNAs and the constantly expressed beta-actin (beta-ACT) mRNA were simultaneously amplified in one multiplex PCR reaction. The PCR conditions were optimized to minimize mutual inhibition of individual amplifications. One of the PCR primers in each primer pair was biotinylated, and the PCR products were captured onto streptavidin-coated microtitre plates. The three PCR products were detected with three different lanthanide labelled target-specific probes in solution hybridization. IFN-gamma, IL-4 and beta-ACT were detected with europium (Eu), terbium (Tb) and samarium (Sm) labelled probes, respectively, using time-resolved fluorometry. Small cell numbers used in microtitre plate cultures were sufficient to detect cytokine messages after mitogen stimulation. This sequence-based method provides a sensitive, specific, fast and nonisotopic alternative to conventional blotting and hybridisation with radioactive probes. In addition, the multiplex fluorogenic dye detection facilitates relative quantification of target mRNAs.

Development of human antibodies against linear antigenic and immunogenic regions of respiratory syncytial virus (RSV) nucleocapsid and phospho-proteins shows the site-directed characteristics

BACKGROUND

The successful development of an RSV vaccine requires a better understanding of the pathogenesis of primary infection, susceptibility to reinfection, and the immunopathology of enhanced illness in children immunized with a non-replicating RSV candidate vaccine. The exact role of different immune parameters in RSV pathogenesis remains controversial.

OBJECTIVES

To study the contribution of antibodies directed to the linear antigenic and immunogenic regions of the N and P proteins in the titer rise and avidity maturation of total anti-RSV antibodies.

STUDY DESIGN

The occurrence of antibodies directed against three linear antigenic and immunogenic regions in each of the nucleocapsid (N): N3 (Thr11 to Gly30), N25 (Ser231 to Ala250) and N39 (Thr371 to Leu391), and the phospho-(P) proteins of respiratory syncytial virus (RSV), subgroup A: P49 (Pro91 to Asp110), P56 (Ser161 to Lys180) and P62 (Glu221 to Phe241), were analyzed in ELISA with (a) 32 paired sera from humans with recent or previous RSV subgroup A and/or B infection diagnosed by conventional ELISA, detection of antigen in nasopharyngeal aspirates and measurement of antibody avidity change; and (b) 40 RSV antibody-positive sera (HCS) obtained from patients during their convalescence from RSV infection and possessing clearly demonstrable titers of RSV IgG in conventional enzyme immunoassays (EIA) based on whole RSV antigen.

RESULTS

The titer rise of antibodies directed to the combined three peptides representing the RSV N protein was well correlated with the rise in anti-RSV antibodies measured in whole antigen ELISA. Surprisingly, the rise in antibodies against a truncated main C-terminal epitope (Gln381 to Leu391) of the N protein (represented by subgroup A specific sequence of the N39/1 peptide) was inversely correlated with the titer rise of total anti-RSV antibodies. The titer rise of antibodies to the C-terminal linear site of the RSV N (N39/1) protein was subgroup-specific during the course of primary RSV infection. A titer rise in antibodies to the C-terminal linear sites of RSV N (i.e. N39/1) and P (P62) proteins had a dominating appearance in sera from newborn infants (6-7 months) and from patients with RSV reinfections. Anti-RSV antibody titers of late convalescent sera correlated with the titers of antibodies directed to the C-terminal linear site of RSV P (P62) protein. The avidity maturation of the anti-RSV immune response followed the titer rise of anti-P62 antibodies during the course of primary or secondary RSV infection.

A new method for automatic wheeze detection

A new automatic wheeze detection method which is based on image processing techniques applied to the sonagram was developed here. In the calculation of the sonagram, autoregressive and FFT spectrum estimation methods were compared. The method was validated in four wheezing asthmatic patients by a pulmonary physician. Nine out of ten wheezes longer than 250 ms were detected. Very short wheezes were not detected. The false positive amount of wheezing in control subjects was only about 1%. The method extracts also information about the frequency, duration, flow and volume associated with the wheezes.

Intranasally administered immunoglobulin for the prevention of rhinitis in children

OBJECTIVE

To determine the efficacy of intranasally administered immunoglobulin in preventing symptoms of rhinitis in children.

METHODS

Forty children ages 1 to 4 years who attended day-care centers in Turku, Finland, were enrolled in the double blind, placebo-controlled study. The children were randomly assigned to receive treatment with immunoglobulin, composed mainly of immunoglobulin A, or placebo, both administered as nasal sprays twice daily for 8 weeks. During this medication period and an additional 8-week follow-up period, the parents recorded the symptoms of the children daily in the diaries provided. One child who met an exclusion criterion was withdrawn from the study after a few days of medication.

RESULTS

During the 8-week medication period the 19 children in the immunoglobulin group had 42% fewer days with rhinitis than the 20 children receiving placebo (mean, 10.8 vs. 18.7 days; P=0.004). The total numbers of episodes of rhinitis in the immunoglobulin and placebo groups were 33 and 51, respectively. No significant differences were observed between the groups during the postmedication follow-up period.

CONCLUSIONS

Intranasal administration of immunoglobulin appears to be an effective method to prevent symptoms of rhinitis in children, and further studies of this approach are needed.

Incidence of acute otitis media associated with group A and B respiratory syncytial virus infections

The comparative association of respiratory syncytial virus group A and B infections with acute otitis media was determined by analysing the hospital records of children with community-acquired respiratory syncytial virus infection during three successive outbreaks from 1987 to 1992. Of 326 episodes analysed, 192 (59%) were caused by group A and 134 (41%) by group B infections. Acute otitis media was diagnosed in 101 (75%) children with group B infection, compared with 119 (62%) with group A infection (p = 0.01). Group A infections were more often associated with wheezing (71% versus 59% in group B; p = 0.02) and oxygen therapy in inpatients (48% versus 31%, respectively; p = 0.008). The higher incidence of acute otitis media associated with group B infections was observed both after adjustment for potential confounding variables and during each outbreak.

Preparation of monoclonal antibodies for the diagnosis of influenza A infection using different immunization protocols

Four immunization protocols were used to obtain cross-reactive influenza type A-specific monoclonal antibodies: (1) repeated administration of purified influenza virus, (2) immunization with bromelain-treated viral particles free of HA and NA, (3) sequential immunization with two strains of different subtypes, and (4) immunization with bromelain-treated particles following tolerization of mice to surface glycoproteins by cyclophosphamide. The fourth approach was shown to be the most effective since a high proportion of hybridomas producing cross-reactive influenza virus type A-specific MAbs were obtained. MAbs of type A specificity were immunochemically characterized and examined for their ability to detect virus in clinical specimens. It was demonstrated that two pairs of the newly prepared MAbs provided excellent reagents for viral detection in clinical specimens using time-resolved fluoroimmunoassay.

Inhibition of herpes simplex virus type 1, respiratory syncytial virus and echovirus type 11 by peroxidase-generated hypothiocyanite

The human mouth is an important route of viral transmission and evidence exists that human saliva can neutralize some viruses, e.g. herpes simplex type 1 (HSV-1) and human immunodeficiency virus (HIV) in vitro. However, little is known of the actual antiviral agents in saliva. We have analyzed how hypothiocyanite (HOSCN/-OSCN) ions, present in human saliva and generated by salivary peroxidase systems, affect the viability of three different types of viruses; HSV-1 (capable of inducing oral lesions), respiratory syncytial virus (RSV, respiratory infections), and echovirus 11 (EV 11, enteric diseases). Viral suspensions were pretreated (30 min) with HOSCN/-OSCN concentrations up to 180 microM both at pH 6.0 and 7.1 and inoculated into human gingival fibroblasts. The cultures were incubated at 37 degrees C for 18-48 h, fixed and the infected cells were counted after immunoperoxidase staining. HSV-1 was most sensitive to HOSCN/-OSCN with an IC50 of 8.5 microM at pH 6.0 and an IC50 of 20 microM at pH 7.1, respectively. RSV was inhibited by HOSCN/-OSCN only at pH 6.0 with an IC50 of 8.0 microM. EV 11 was also resistant at neutral pH, but sensitive at pH 6.0 with an IC50 of 68 microM. In contrast to HSV-1 and RSV, the inhibition of EV 11 was not dependent on the concentration of HOSCN/-OSCN. The inhibition was in all cases stronger at pH 6.0 than at neutral pH. Our results suggest that hypothiocyanite, a normal component of human whole saliva, in physiological concentrations effectively inhibits HSV-1 and RSV at acidic pH, whereas EV 11 is more resistant in vitro.

Short-term use of amoxicillin-clavulanate during upper respiratory tract infection for prevention of acute otitis media

We performed a randomized, double-blind, placebo-controlled study to determine whether acute otitis media could be prevented by antibiotic therapy initiated promptly after the appearance of symptoms of upper respiratory tract infection. One hundred four children aged 1 to 4 years received a 7-day course of either amoxicillin-clavulanate or placebo. Acute otitis media developed in 9 (18%) of the 50 children receiving amoxicillin clavulanate and in 12 (22%) of the 54 children receiving placebo (p = 0.59).

Linear antigenic and immunogenic regions of human respiratory syncytial virus N protein

Three linear antigenic regions on the N protein from human respiratory syncytial virus (RSV) subgroup A (strain A2) were identified by using peptides which reacted in ELISA with sera from humans with recent or previous RSV infection. The determinants were localized within three hydrophilic regions of the protein: Thr11 to Gly30 (N3 peptide), Ser231 to Ala250 (N25 peptide) and Thr371 to Leu391 (N39 peptide). The site represented by the N39 peptide reacted with four subgroup A-specific MAbs. There were minor variations in the amino acid epitope dependencies of each of these MAbs. Two additional antigenic regions Ser131 to Arg150 and Ala181 to Leu200, were represented by peptides that reacted with human convalescent sera, but these peptides did not differentiate between acute and convalescent sera from RSV-infected humans. Rabbit hyperimmune sera raised against selected peptides specifically precipitated different forms of the N protein from a nucleocapsid-containing homogenate derived from extracts of RSV-(subgroup A and/or B)-infected 35S-labelled cells in a radioimmuneprecipitation assay (RIPA); the sera were also used to demonstrate RSV infection in cells by immunofluorescent assay (IFA). Anti-N3 peptide sera precipitated N41, the full-length (M(r) 41,000) form of N protein, in a RIPA done on a soluble protein pool. Anti-N39 (C-terminal region) peptide sera precipitated both forms, suggesting that N38 (M(r) 38,000) is an N-terminally truncated (probably at position Tyr23 located inside the N3 peptide linear antigenic region) form of N41 protein.

Linear antigenic and immunogenic regions of the respiratory syncytial virus P protein

Three linear antigenic regions on the P protein from human respiratory syncytial virus (RSV) subgroup A (strain A2) were represented by peptides that reacted with monoclonal antibodies and with sera from humans with recent or previous RSV infection. The determinants were localized within three hydrophilic regions of the P protein: Pro91 to Asp110, Ser161 to Lys180 and Glu221 to Phe241. The role of individual amino acids in the epitopes defined by monoclonal antibodies was determined. Two monoclonal antibodies reacting with the same antigenic site were found to detect epitopes that had different amino acid dependencies. Rabbit hyperimmune sera raised against selected peptides specifically precipitated different forms of the P protein from RSV-infected 35S-labelled cell extracts in a radioimmune precipitation assay. These findings have implications for forthcoming structural-functional studies of RSV capsid component interactions and also for serological diagnosis of RSV infection.

Shedding of infectious virus and virus antigen during acute infection with respiratory syncytial virus

Shedding of respiratory syncytial virus (RSV) in nasopharyngeal aspirates (NPA) of hospitalized children with acute respiratory infection was studied using direct antigen detection by time-resolved fluoroimmunoassay, rapid identification of infectious virus in centrifugally inoculated cell cultures by immunoperoxidase staining and conventional virus culture. Sequential NPAs, in which also local RSV-specific IgA response was measured, were collected from children with proven RSV infection. The shedding pattern was similar for both infectious virus and viral antigen. The overall agreement of the three methods was good (81%) in diagnostic specimens collected on admission, but markedly reduced (46%) in follow-up specimens. Secretory IgA was abundant in specimens giving discrepant or negative results only. The proportion of patients who shed RSV was high (> or = 87%) in the first week after onset of symptoms, and decreased sharply in the second week. An opposite temporal pattern was found in the proportion of patients with detectable RSV-IgA in their secretions. Sequentially isolated strains were antigenically stable as determined by their reactivity with a large panel of monoclonal antibodies. The findings suggest that RSV shedding should be monitored by using more than one method for virus detection.

Immunoglobulin G antibody avidity in patients with respiratory syncytial virus infection

The titer and avidity of respiratory syncytial virus-specific antibodies were measured in 196 serum specimens from 93 children with an acute, laboratory-confirmed respiratory syncytial virus infection. An enzyme immunoassay method based on the ability of urea to dissociate the bound antibodies with low avidity from the antigen was used. Three patterns of immune responses were observed. Children less than 6 months of age usually had low titers of antibodies with high avidity in their acute-phase serum samples. These antibodies were concluded to be of maternal origin, since their reaction pattern was similar to that of healthy adults. During the next few weeks, a slight increase in titers with a concurrent decrease in antibody avidity was observed. All children 6 to 24 months of age had low-avidity antibodies in their acute-phase serum samples, which matured to high avidity during the follow-up. On the contrary, about half of the children greater than 24 months of age had high-avidity antibodies already in the acute-phase serum samples. We conclude that the former children were experiencing primary infections with respiratory syncytial virus and the latter were experiencing reinfections. All adults with remote immunity had antibodies with high avidity.

Influenza vaccination in the prevention of acute otitis media in children

We studied a new approach to the prevention of acute otitis media through the administration of influenza vaccine to 187 day-care center children aged 1 to 3 years before the influenza A epidemic of 1988-1989. The control group consisted of 187 unvaccinated children of similar age and background. During the 6-week study period, influenza A infection was diagnosed in five (3%) of 187 vaccinees and in 29 (16%) of 187 controls. Acute otitis media developed in three (60%) of five vaccinees with an influenza A infection compared with 18 (67%) of 27 controls (excluded were two children with a double viral infection). The incidence of acute otitis media associated with influenza A was reduced by 83% in the vaccinees. The total number of children with acute otitis media in the vaccine group was 35, compared with 55 in the control group, disclosing a 36% reduction among the vaccinees. We conclude that influenza vaccination decreases the incidence of acute otitis media in children during an influenza A epidemic, suggesting also that other vaccines against respiratory viruses may be an effective way to reduce the incidence of acute otitis media.

Facile detection of anatoxin-a in algal material by thin-layer chromatography with Fast Black K salt

A method for facile high-capacity screening of algal samples for anatoxin-a (ANTX-a), a potent neurotoxin of Anabaena flos-aquae, is presented. The method is based on in situ colour reaction of algal extracts containing ANTX-a on a thin-layer chromatographic plate with the diazonium reagent Fast Black K salt, and subsequent separation of the orange-red product. The product, shown to be a stable 3,3-dialkyltriazene, is derived from a reaction involving the aliphatic secondary amino group of ANTX-a. The detection limit for ANTX-a is 10 micrograms g-1 of lyophilized algal material, which is comparable to earlier methods using more complex instrumentation.

Pattern of respiratory syncytial virus epidemics in Finland: two-year cycles with alternating prevalence of groups A and B

Time-resolved fluoroimmunoassay with monoclonal antibodies distinguishing between respiratory syncytial virus (RSV) group A and B strains was used to analyze their prevalence in Finland during 1981-1990 among 3285 patients with laboratory diagnosis of RSV, most of them hospitalized. The group typing of antigens in 608 RSV-positive nasopharyngeal aspirates showed a regular alternation of group prevalence, following the cyclic occurrence of the virus. Group A predominated in 73%-90% of specimens from 1981-1982, 1985-1986, and 1989-1990, whereas group B predominated in 70%-100% of specimens from 1983-1984 and 1987-1988. The epidemiologic occurrence of verified reinfections in hospitalized children and the group typing results indicated that children greater than 6 months of age during the first infection were more resistant to severe reinfection with the homologous than with the heterologous group of virus. The study shows that group antigenic variation of RSV has a significant effect on the epidemiology of the virus.

Rapid detection of respiratory syncytial virus and influenza A virus in cell cultures by immunoperoxidase staining with monoclonal antibodies

Peroxidase-labeled monoclonal antibodies against respiratory syncytial virus (RSV) and influenza A virus were used for immunoperoxidase staining (IPS) of cell cultures inoculated with nasopharyngeal aspirates. Cells were grown in 24-well plates, and specimens were inoculated by low-speed centrifugation. Cultures were incubated for 2 days at 37 degrees C and then fixed, stained, and observed by light microscopy. IPS was compared with standard virus isolation by using cultures of human diploid fibroblasts and Vero, HEp-2, and HeLa cell lines for RSV and Madin-Darby canine kidney cells for influenza A virus; these cultures were inoculated with specimens that were previously stored at -70 degrees C. Of 40 known RSV-positive specimens, 30 were found to be positive on reinoculation by both methods, and an additional 5 specimens were found to be positive by IPS only. Of 190 specimens tested for influenza A virus, 14 were positive by IPS and in tubes, and a further 8 specimens were positive by IPS only. IPS was also compared with direct detection of viral antigens in nasopharyngeal aspirates by a time-resolved fluoroimmunoassay (TR-FIA). Fresh nasopharyngeal aspirates were inoculated into human diploid fibroblasts and Madin-Darby canine kidney cells and tested for RSV and influenza A virus, respectively, by IPS. Of 110 specimens tested for RSV, 37 were positive in total, 32 were positive by IPS, and 33 were positive by TR-FIA. Of 150 specimens tested for influenza A virus, 39 were positive in total, 35 were positive by IPS, and 34 were positive by TR-FIA. IPS of cultures inoculated by centrifugation and incubated for 2 days is a sensitive method for the diagnosis of respiratory virus infections, and 24-well plates allow for the easy processing of a large number of specimens.

One-incubation time-resolved fluoroimmunoassay based on monoclonal antibodies in detection of influenza A and B viruses directly in clinical specimens

A new modified enzyme immunoassay screening method was developed for testing hybridoma cultures, so as to select antibodies useful for solid phase assays. Samples of hybridoma cultures were incubated for 1 h with purified nucleoprotein preparation in microtiter wells precoated with rabbit anti-influenza A or B immunoglobulin, followed by washing and addition of anti-mouse HRPO-conjugate. The monoclonal antibodies were then used in one-incubation time-resolved fluoroimmunoassay (TR-FIA) for detecting influenza viral proteins in nasopharyngeal aspirate specimens. The sample and europium (Eu)-labelled monoclonal detector antibody (100 microliter of each) were added simultaneously to microtiter wells precoated with anti-virus monoclonal antibody, and incubated for 1 h. After washing and addition of the enhancement solution the strips were shaken for 10 min before measurement of the fluorescence using a photon counting fluorometer. All of the monoclonal antibodies screened by our modified method and Eu-labelled worked as detector antibodies. Many of these monoclones also functioned as capture antibodies on solid phase. A total number of 309 (influenza A) and 104 (influenza B) nasopharyngeal aspirate specimens taken mainly from hospitalized children with acute respiratory disease were tested with the TR-FIA, using monoclonal antibodies produced by our modified screening method in comparison with monoclonal antibodies previously reported elsewhere (Walls et al., 1986). Results were similar, and superior to those obtained with routinely used indirect enzyme immunoassay based on polyclonal antibodies. The results of this study indicate that the one-incubation TR-FIA using monoclonal antibodies selected by the modified screening method is a highly sensitive and rapid method for detecting influenza A and influenza B virus in clinical specimens.

Time-resolved fluoroimmunoassay compared with virus isolation for rapid detection of respiratory syncytial virus in nasopharyngeal aspirates

Two monoclonal antibodies against two distinct conserved epitopes of the respiratory syncytial virus (RSV) nucleocapsid protein were used in a direct time-resolved fluoroimmunoassay (TR-FIA) for the detection of RSV antigens in nasopharyngeal aspirates. The capture antibody was adsorbed to the solid phase of microdilution strip wells, and the indicator antibody was labeled with a europium chelate. Specimens and label were incubated simultaneously for 1 h at 37 degrees C in the coated wells. After the test samples were washed, fluorescence enhancement solution was added, strips were shaken, and the time-resolved fluorescence was measured. The test procedure took only 75 min, and the total time for 20 specimens, with pretreatment by sonication, was 2 to 3 h. We prospectively evaluated the detection of RSV in nasopharyngeal aspirates of pediatric patients by TR-FIA and by virus isolation in human diploid fibroblasts. TR-FIA detected 40 of 42 isolation-positive specimens. Nine additional isolation-negative specimens were positive by TR-FIA; all proved to be true positives by a blocking-type confirmatory assay. The sensitivity, specificity, positive predictive value, and negative predictive value for TR-FIA were 95, 96, 82, and 99%, respectively, of the values obtained by virus isolation and 96, 100, 100, and 99%, respectively, of the values obtained by virus isolation and the confirmatory assay.

Herpes simplex virus detection by macroscopic reading after overnight incubation and immunoperoxidase staining

Human diploid foreskin fibroblast cells grown in 24-well plates were inoculated with clinical specimens by centrifugation at 1,000 X g for 45 min. Cultures were incubated at 37 degrees C overnight, fixed, and stained with peroxidase-labeled monoclonal antibodies against herpes simplex virus types 1 and 2. Stained plaques of infected cells were large enough to be detected with the naked eye, and microscopic examination did not reveal any further positive specimens. The method was compared with standard isolation in human fibroblasts grown in shell vials and inoculated by centrifugation at 4,000 X g, observed microscopically for the occurrence of typical cytopathogenic effect three times a week for 10 days, and then typed by enzyme immunoassay. Of the 289 specimens tested, 105 were positive and 174 were negative by both methods. Six specimens were positive by standard isolation only, two of them containing varicella-zoster virus, and two specimens were stored frozen before being tested by immunoperoxidase staining. Two specimens found negative by standard isolation were positive by immunoperoxidase staining. For two specimens negative by immunoperoxidase staining, the standard isolation cultures were lost due to microbial contamination. Forty-two specimens found positive by standard isolation were clearly positive when stained only 8 h after inoculation. By standard isolation, positive results were reported on the average 3 to 4 days after inoculation, whereas by immunoperoxidase staining the result was available within less than 24 h. Immunoperoxidase staining of infected cells is a sensitive method for rapid laboratory diagnosis of herpes simplex virus infections, and 24-well plates are convenient for the handling of a large number of specimens.

Purification of adenovirus hexon protein by high-performance liquid chromatography

Adenovirus (Type 2)-infected HeLa cells were sonicated and treated with 1,1,2-trichlorotrifluoroethane. The water-soluble extract was ultracentrifuged and the supernatant, containing the dissociated proteins, was subjected to anion-exchange high-performance liquid chromatography on a Mono Q column in 50 mM bis-Tris-HCl (pH 6.5). Elution with a linear salt gradient resulted in a major peak, containing the hexon protein.