Cyclovirus detection in Chilean adults with and without community-acquired pneumonia

Cycloviruses (CyV) (genus Cyclovirus, family Circoviridae) are nonenveloped DNA viruses. The first report in humans was in 2010 and research has focused only on disease-associated human sample detection. The only HuACyV (CyCV-ChileNPA1, HuACyV10) reported in the Chilean population was in children (3.3%) with an acute respiratory infection. Its detection in respiratory samples from adults, with/without respiratory disease remains unknown. The aim of this study was to detect HuACyV10 in adults with and without respiratory disease. HuACyV10 was studied in nasopharyngeal swabs from 105 hospitalized adults with community-acquired pneumonia (CAP) and 104 adults without respiratory symptoms. Total nucleic acids were extracted, and viral rep and cp gene fragments were amplified by real-time polymerase chain reaction. HuACyV10 was detected in 19.05% adults with CAP and in 0.96% asymptomatic adults, being significantly higher in adult CAP than asymptomatic (n = 1) ones (p = 0.0001). C _t values were between 26.7 and 39.6, and the median was 34.1 for rep and 33.8 for the CAP in adults CAP (p = 0.68), and 35.7 and 36.0, respectively, in the asymptomatic case. HuACyV10 detection in CAP adults concentrated in the Autumn-Winter season of the Southern hemisphere. The only asymptomatic adult with HuACyV10 was detected in the Spring-Summer period. In this first report of HuACyV10 in respiratory samples from adults, detection was significantly higher in CAP than in asymptomatic adults. As the sensitivity of both rep and cp genes was similar, both can be applied for detecting HuACyV10. It would be advisable to investigate the pathogenic role of HuACyV10 in adult respiratory infections. ​.

Comparison of Luminex xTAG® RVP fast assay and real time RT-PCR for the detection of respiratory viruses in adults with community-acquired pneumonia

Community‐acquired pneumonia (CAP) is the third cause of death worldwide. Viruses are frequently detected in adult CAP. Highly sensitive diagnostic techniques should be used due to poor viral shedding. Different sampling methods can affect viral detection, being necessary to establish the optimal type of sample for identifying respiratory viruses in adults. The detection rates of respiratory viruses by Luminex xTAG® RVP fast assay, real time RT‐PCR (rtRT‐PCR) (Sacace®), and immunofluorescence assay (IFA) in adult CAP were performed in nasopharyngeal swabs (NPS) and aspirates (NPA) from 179 hospitalized adults. Positivity was 47.5% for Luminex®, 42.5% for rtRT‐PCR (P = 0.3), and 2.7% for IFA (2.7%) (P < 0.0). The sensitivity, specificity, and kappa coefficient of xTAG® RVP compared with rtRT‐PCR were 84.2%, 79.6%, and 0.62%, respectively. Luminex® and rtRT‐PCR detected 65 (58.0%) and 57 (50.9%) viruses in 112 NPA and 35 (34.3%) and 31 (30.4%) in 102 NPS, respectively (P < 0.01). xTAG® RVP is appropriate for detecting respiratory viruses in CAP adults. Both molecular techniques yielded better results with nasopharyngeal aspirate than swabs. J. Med. Virol. 88:1173–1179, 2016. © 2016 Wiley Periodicals, Inc.

Relationship between severity of adult community-acquired pneumonia and impairment of the antioxidant defense system

Oxidant/antioxidant imbalance has been reported in some infectious diseases, including community-acquired pneumonia (CAP). The aim was to assess the antioxidant status in adults with CAP and its relationship with clinical severity at admission. Fifty-nine patients with CAP were enrolled and categorized at admission by the FINE score, from July 2010 to October 2012. In the same period 61 controls were enrolled. Plasma samples were obtained at admission for determination of the ferric reducing ability of plasma (FRAP) and lipid peroxidation (8-isoprostane). Erythrocyte reduced (GSH)/oxidized (GSSG) glutathione, malondialdehyde (MDA) and antioxidant enzyme activity were assessed. Antioxidant status in adults with CAP represented by FRAP and the GSH/GSSG ratio were 16.8% (p=0.03) and 39.7% (p=0.04) lower than control values, respectively. In addition, FRAP values showed a positive correlation with GSH/GSSG ratio (r=0.852; p<0.02; n=59). The CAP group showed greater lipid peroxidation in both plasma and erythrocytes. The FINE score correlated negatively with FRAP (r= -0.718; p<0.05; n=59) and positively with MDA and F2 isoprostane levels (r=0.673; p<0.05; n=59; r=0.892; p<0.01; n=59, respectively). Antioxidant status alterations correlated with clinical severity. The FRAP assay and lipid peroxidation biomarkers may provide a useful parameter for estimating the severity and the clinical outcome of patients with CAP.

Cyclovirus in nasopharyngeal aspirates of Chilean children with respiratory infections

Some respiratory tract infections remain unexplained despite extensive testing for common pathogens. Nasopharyngeal aspirates (NPAs) from 120 Chilean infants from Santiago with acute lower respiratory tract infections were analysed by viral metagenomics, revealing the presence of nucleic acids from anelloviruses, adenovirus-associated virus and 12 known respiratory viral pathogens. A single sequence read showed translated protein similarity to cycloviruses. We used inverse PCR to amplify the complete circular ssDNA genome of a novel cyclovirus we named CyCV-ChileNPA1. Closely related variants were detected using PCR in the NPAs of three other affected children that also contained anelloviruses. This report increases the current knowledge of the genetic diversity of cycloviruses whose detection in multiple NPAs may reflect a tropism for human respiratory tissues.

Role of neutralizing antibodies in adults with community-acquired pneumonia by respiratory syncytial virus

Background. Respiratory syncytial virus (RSV) has been implicated in the etiology of adult community-acquired pneumonia (CAP). We investigated RSV infection in Chilean adults with CAP using direct viral detection, real-time reverse-transcription polymerase chain reaction (rtRT-PCR), and serology (microneutralization assay).

Methods. RSV, other respiratory viruses, and bacteria were studied by conventional and molecular techniques in adults aged ≥18 years presenting with CAP to the healthcare facilities in Santiago, Chile from February 2005 through December 2007.

Results. All 356 adults with CAP enrolled had an acute blood sample collected at enrollment, and 184 had a convalescent blood sample. RSV was detected in 48 cases (13.4%). Immunofluorescence assay and viral isolation each detected only 1 infection (0.2%), whereas rtRT-PCR was positive in 32 (8.9%) cases and serology was positive in 20 (10.8%) cases. CAP clinical characteristics were similar in RSV-infected and non-RSV-infected cases. RSV-specific geometric mean serum-neutralizing antibody titer (GMST) was significantly lower at admission in the 48 RSV-infected cases compared with 308 non-RSV-infected adults (GMST in log₂: RSV/A 8.1 vs 8.9, and RSV/B 9.3 vs 10.4; P < .02).

Conclusions. RSV infection is frequent in Chilean adults with CAP. Microneutralization assay was as sensitive as rtRT-PCR in detecting RSV infection and is a good adjunct assay for diagnostic research. High RSV-specific serum-neutralizing antibody levels were associated with protection against common and severe infection. The development of a vaccine could prevent RSV-related CAP in adults.

Identification of P1 types and variants of Mycoplasma pneumoniae during an epidemic in Chile

This study was conducted to determine the types of M. pneumoniae prevalent in adults presenting with community-acquired pneumonia during an epidemic period, and to scrutinize a variable region of the RepMP4 element for the detection of P1 variants. All 23 clinical specimens PCR-positive for M. pneumoniae obtained in two hospitals in Santiago, Chile, from 2005 to 2006 were typed by a multiplex PCR directly and then the RepMP4 fragment of 18 specimens was sequenced. A predominance of M. pneumoniae type 2 was found, 18 (78.3 %) specimens being grouped as type 2 and 5 (21.7 %) as type 1. Co-infection of M. pneumoniae with other respiratory pathogens was found in 10/23 (43.4 %) patients, but their frequency was not related to the M. pneumoniae type. Sequence analysis revealed a single nucleotide polymorphism, a transition mutation, in 50 % of amplicons belonging to type 1 and in 71.4 % of amplicons of type 2. The nucleotide changes were synonymous in each P1 variant. In conclusion, during the 2005–2006 epidemic in Santiago, both types of M. pneumoniae circulated. Although the analysed area in the RepMP4 was small, we detected the existence of P1 variants in the two types of this organism.

Impaired immune response in severe human lower tract respiratory infection by respiratory syncytial virus

BACKGROUND

Respiratory syncytial virus (RSV) is a major cause of acute lower respiratory infection in infants. The immune response plays a leading role in the severity of the disease. We hypothesized that severe RSV disease is associated with an impaired immune response characterized by low circulating T lymphocytes and plasma cytokine concentrations.

METHODS

We evaluate the in vivo immune responses of previously healthy infants with their first proven RSV-acute lower respiratory infection that required hospitalization. According to the clinical severity, defined by using a strict scoring system, the in vivo immune response was compared through the analysis of plasma cytokine values and the phenotyping of peripheral blood lymphocyte and natural killer (NK) cells.

RESULTS

Absolute blood cell counts of CD4+, CD8+, and CD19+ lymphocytes and NK cells were lower in subjects with RSV than in control infants. Lowest cell counts were observed in more severe RSV-infected infants. Significant low values were obtained in CD8+ lymphocytes (P = 0.03) and nonactive NK cells, that express CD94 antigen (P = 0.046). In contrast, activated NK cells that do not express CD94 molecules were significantly higher in RSV infected infants than in healthy controls (% of cells: P = 0.004). The interferon-gamma and tumor necrosis factor-alpha values in RSV infected patients were lower than in controls subjects. Interleukin-17 cytokine was not detected in healthy infants and the largest concentration was found in moderately ill patients as compared with severe cases (P = 0.033). RSV infection showed significantly higher interleukin-8 chemokine than in control infants (P = 0.024).

CONCLUSION

We propose that severe RSV infection in very young infants is associated with poor blood proinflammatory cytokine production, low counts of CD8+ T cells and with a greater activity of a group of NK cells, that are independent of the major histocompatibility complex class Ib recognition system.

Detection of Mycoplasma pneumoniae in adult community-acquired pneumonia by PCR and serology

Diagnosis of pneumonia caused by Mycoplasma pneumoniae in adults is hampered by a lack of rapid and standardized tests for detection. This prospective study was conducted to compare the diagnostic values of an indirect immunofluorescence assay and a 16S rRNA gene PCR for the diagnosis of M. pneumoniae pneumonia in adults. From February 2005 to January 2008, 357 patients (53.8 % males, median age 63 years, range 18-94) admitted for community-acquired pneumonia (CAP) to two hospitals in Santiago, Chile, were enrolled in the study. Thirty-two patients (9.0 %) met the criteria of current or recent M. pneumoniae infection, and laboratory diagnosis was definitive in 26 cases (81.2 %) and presumptive in six cases (18.8 %). Among the 32 M. pneumoniae infections, the PCR assay was positive in 23 (71.9 %) and the serology in 27 (84.4 %) of the cases. IgM was positive in acute-phase serum specimens in 13 cases (40.6 %) of M. pneumoniae infections. Using serology as the gold standard, the sensitivity, specificity, and positive and negative predictive values of the PCR were 66.7, 98.5, 78.3 and 97.3 %, respectively, whereas the global agreement of the methods was 343/357 (96.1 %). The frequency of M. pneumoniae CAP cases declined significantly during the second year of study, suggesting the end of an epidemic period. In conclusion, although good global agreement was found between PCR and serology, the lower sensitivity of the PCR leads us to recommend the use of both procedures in parallel to confirm M. pneumoniae in CAP in adults.

Detection of Pneumocystis carinii f. sp. hominis and viruses in presumably immunocompetent infants who died in the hospital or in the community

Fresh-frozen lung and tracheal-aspirate specimens obtained from 112 infants who died in Santiago, Chile, during 1998-2000 were analyzed for the presence of Pneumocystis DNA, by use of nested DNA amplification of the large subunit mitochondrial rRNA, and for the presence of viruses, by use of culture and immunofluorescence. Pneumocystis DNA was detected in specimens from 45 (51.7%) of 87 infants who died in the community and from 5 (20%) of 25 infants who died in the hospital (P=.006). Primary infection with Pneumocystis was highly frequent among infants who die unexpectedly in the community. Infection with viruses was more common in infants who died in the hospital.

Adenovirus and respiratory syncytial virus-adenovirus mixed acute lower respiratory infections in Chilean infants

BACKGROUND

In Chile respiratory syncytial virus (RSV) and adenovirus (AD) are the principal viruses detected in acute lower respiratory infections (ALRI) in infants. An overview of AD pneumonia in Chile to detect annual trends and to compare the severity of single AD or mixed RSV-AD infections is presented.

METHODS

Surveillance in 4927 infants hospitalized for ALRI has been performed from 1989 to 2001 using immunofluorescence assay (IFA) and viral isolation. Clinical features in 117 infants with single genotyped AD and 81 infants with mixed RSV-AD infections were analyzed.

RESULTS

Adenovirus cases declined from 20% annually in the early 1990s to approximately 5% in the 2000 decade. Genotype 7h showed increasing prevalence in hospitalized cases. The mean annual burden of hospitalizations caused by AD in Santiago was estimated to be 0.6%. No difference was observed in duration of fever, oxygen requirement and hospital stay between groups. Lung consolidation was more frequent in AD cases than mixed cases (P < 0.01); interstitial pattern and hyperinflation prevailed in the mixed cases (P < 0.01). No child died. AD diagnosis was confirmed on admission by IFA in 17% of cases of RSV-AD and in 43% of cases of single AD ALRI. AD cases diagnosed early by IFA had worse clinical outcome than those diagnosed later by virus isolation (P < 0.05).

CONCLUSIONS

AD cases declined since 1989. Mixed RSV-AD infections were not more severe than single AD etiology. AD cases admitted with positive IFA had worse prognoses than AD infections diagnosed later by virus isolation.

Surveillance for respiratory syncytial virus in infants hospitalized for acute lower respiratory infection in Chile (1989 to 2000)

Hospitalized infants (4,618) were studied for lower respiratory infections from 1989 through 2000 by routine immunofluorescence assay and viral isolation. The hospitalization rate for respiratory syncytial virus (RSV) averaged 2% per year. The fatality rate was 0.1%. Monthly RSV detection varied from 14 to 88%, and epidemics lasted 3.5 to 6 months. From 1994 high-early versus low-late epidemic patterns alternately were observed, the first influenced by a group B strain.

[The influence of winter 2002 in pediatric health: dissociation between environmental factors and respiratory syncytial viruses, in Santiago]

BACKGROUND

The increase in winter related health pediatric demand is associated with three factors: cold and rainy weather, air pollution and respiratory viral epidemics. During the winter of 2002 there was, successively, heavy rain, air pollution, cold weather and a respiratory syncytial virus (RSV) epidemic in Santiago.

AIM

To study the influence of environmental factors and RSV epidemic on pediatric health care demand.

PATIENTS AND METHODS

The number of hospital admissions and outpatient consultations for acute lower respiratory infections (ALRI) from April to October 2002 (Autumn to Spring in Chile), were registered in a public pediatric hospital of Santiago. A respiratory virus surveillance (RSV, adenovirus influenza and parainfluenza virus) was carried out among children admitted for ALRI. Climate conditions and air pollution (number of particles of more than 10 microns/mm3) values were provided by local environmental health services.

RESULTS

As expected, a rise in winter hospital admissions and outpatient consultations was detected, that peaked in week 29. This rise coincided with the higher RSV detection week. There was heavy rain in weeks 22, 23 and 30, as well as cold weather in June-July (weeks 23, 24, 26, 27 and 30; mid Winter), that did not increase health care demand. Likewise, high air pollution, registered from weeks 24 to 26, did not increase health care demand.

CONCLUSIONS

RSV epidemic is the principal factor associated to the increase in health burden during winter in Santiago.

Human caliciviruses are a significant pathogen of acute sporadic diarrhea in children of Santiago, Chile

Human caliciviruses (HuCVs) are increasingly recognized as common pathogens that cause acute sporadic diarrhea in children; however, regional antigenic and genetic diversity complicate detection techniques. Stool samples from children seeking medical attention in 2 outpatient clinics, a large emergency department, and 2 hospital wards were evaluated for HuCVs by reverse transcription-polymerase chain reaction, using primers based on a conserved sequence of the polymerase region of a previously sequenced Chilean strain. HuCVs were detected in 53 (8%) of 684 children 1 month to 5 years of age (mean, 13 months). Detection occurred year-round without a clear seasonal peak, and detection frequency declined from 16% in 1997 to 2% in 1999. The decline may have been due to a change in virus genotype. HuCVs are a significant pathogen of acute sporadic diarrhea in Chilean children, and continuous characterization of genetic diversity will be crucial for appropriate detection.

Hospital-acquired adenovirus 7h infantile respiratory infection in Chile

BACKGROUND

Adenoviruses are the second most common cause of viral acute lower respiratory tract infection (ALRI) requiring hospitalization in Chile. Little information is available with respect to nosocomial infection rate by adenovirus. This issue is important because of its potential severity and long term sequelae.

METHODS

Infants hospitalized for ALRI were studied to determine the rate of nosocomial cross-infection with respiratory adenovirus and its corresponding genome type. The group studied included all cases younger than 2 years of age admitted to a seven crib ward in the Roberto del Rio Children's Hospital (Santiago, Chile) between May, 1995, and October, 1996. Nasopharyngeal aspirates for immunofluorescence assay and viral isolation were obtained on admission and the next day. On identification of a positive case for adenovirus, samples were obtained from contacts for 2 consecutive days and twice weekly thereafter for 2 weeks.

RESULTS

Fifteen index positive cases for adenovirus and their 65 contacts were identified. Secondary attack rate for adenoviral cross-infection was 55%, most of which were diagnosed by viral isolation. Mortality occurred in 4 cases; 3 had underlying diseases. Four secondary cases presented mild respiratory infection after acquiring the cross-infection, and 16 patients developed a moderate and severe ALRI. Twelve patients required supplemental oxygen and 4 needed mechanical respiratory support. Genome types for the 10 index cases and 19 contacts were obtained. All of these corresponded to adenovirus 7h.

CONCLUSIONS

The high secondary attack rate observed, stresses the importance of adequate isolation of patients and the need for rapid and sensitive viral diagnosis.

Adenovirus surveillance on children hospitalized for acute lower respiratory infections in Chile (1988-1996)

Adenoviruses (Ad) play an important role in the etiology of acute lower respiratory tract infections (ALRI) in young children in Chile. Our aim was to correlate the clinical severity of the infections with the Ad strains isolated during surveillance over 8 years. From 1988 through 1996, nasopharyngeal aspirates (NPA) were obtained for viral isolation and immunofluorescence assay (IFA) from children under 2 years of age hospitalized for ALRI; Ad isolates were further studied by restriction enzyme analysis of genomic DNA. Of 3,097 cases enrolled, the Ad isolation rate was 12.6%. The most common admission diagnoses among Ad-positive cases were pneumonia and wheezing bronchitis (69.8%). Duration of Ad shedding was studied in 74 cases by IFA. Children excreting Ad for 4 or more days had a longer hospital stay than those shedding for 1-3 days (mean: 16.8 and 7.2 days, respectively; P <.01). Viral shedding for more than 3 days was associated with more severe outcomes. Genome typing of 221 out of 390 Ad isolates resulted in 87 subgenus C and 134 subgenus B strains, including 123 Ad genome type 7h (55.6%, P <.01). The IFA from the NPA was more sensitive for the detection of subgenus B (51. 5%) than subgenus C infections (24.1%, P <.01). Children shedding Ad 7h had longer hospital stays (P <.01), a higher frequency of rectal temperatures over 39 degrees C (P <.01), and greater need for additional oxygen (P <.02) than subgenus C cases. Four cases requiring mechanical ventilation were associated with Ad 7h infections. The data presented show that, in children hospitalized for ALRI, the genome type 7h was associated with a more severe clinical outcome.

Differential effects of respiratory syncytial virus and adenovirus on mononuclear cell cytokine responses

Respiratory syncytial virus (RSV) and adenovirus (Advs) serotype 3 (Adv3) and 7h (Adv7h) are associated with mild to severe respiratory infection and are indistinguishable during the acute phases of the illnesses. However, outcome and long-term prognosis are different with both infections. RSV infection is associated with later development of asthma, and Adv, mainly Adv7h, with severe lung damage, bronchiectasis, and hyperlucent lung. We hypothesized that this difference could be partly due to different immune responses induced by these viruses. To test this hypothesis we quantified TCD4+, TCD8+, and BCD19+ expressing the interleukin-2 receptor-alpha chain (CD25) and interferon-gamma (IFN-gamma), interleukin (IL)-10, and IL-4 in the supernatant of peripheral blood mononuclear cells (PBMC) from school children infected in vitro with and without RSV, Adv7h, and Adv3 and after phytohemagglutinin (PHA) stimulation in the presence or absence of these viruses at a multiplicity of infection (MOI) of 1. PBMC from every child produced more IL-10 (p </= 0.05) when infected with RSV than with Advs and noninfected control, and Adv induced more (p </= 0.05) IFN-gamma than did RSV and control. The IL-10/IFN-gamma ratio was significantly higher (p </= 0.05) in RSV-infected and significantly lower (p </= 0.05) in Adv-infected PBMC, than in noninfected cells. PHA-stimulated BCD19+ RSV- infected cells expressed more (p </= 0.05) IL-2R than did Adv-infected cells. These results suggest that Advs induce a Th-1-type immune response that is not seen with RSV. These patterns persist despite intersubject variation in the absolute quantity of cytokine produced.

[Systematic surveillance of influenza, syncytial respiratory, parainfluenza and adenovirus in children with acute respiratory infections]

BACKGROUND

The efficacy of influenza vaccination programs depends on the antigenic similitude between vaccine and the influenza virus circulating in the community. Therefore the surveillance of clinical activity and antigenic features of influenza virus is of utmost importance.

AIM

To perform a systematic surveillance of clinical activity and antigenic characteristics of influenza virus.

MATERIAL AND METHODS

Since 1996 and during the cold months (May to September), 20 samples of upper respiratory secretions per week, were obtained from children with acute respiratory infections consulting to the emergency room of a public hospital. Using indirect immunofluorescence and cellular cultures, the presence of influenza, syncytial respiratory, parainfluenza and adenovirus was assessed. The weekly number of consultations in the emergency room and the number of hospital discharges due to acute respiratory infections, were registered.

RESULTS

Influenza and syncytial respiratory were the predominant virus detected since 1996. In 1996 and 1998, the weekly detection of influenza virus followed a single seasonal curve. The maximal weekly positively results reached 85 and 80% of the obtained samples, respectively. During 1997, two curves of influenza virus activity were observed, but none reached more than 50% of weekly positive samples. The demand for outpatient care evolved in parallel to the weekly detection of influenza virus. The hospital discharges due to acute respiratory infections paralleled the syncytial respiratory virus detection rates.

CONCLUSIONS

This surveillance model is effective for the detection of influenza and other virus responsible for acute respiratory infections and their relationship with the demand for health care during the cold months.

[Influence of respiratory viruses, cold weather and air pollution in the lower respiratory tract infections in infants children]

BACKGROUND

All winters, there is an increase in the number of pediatric consultations, associated to three factors: cold weather, air pollution and respiratory virus epidemics.

AIM

To study the influence of these three factors in the demand for pediatric consultations between March and September, in an area of Metropolitan Santiago.

PATIENTS AND METHODS

The number of consultations between March and September 1998 in the emergency room and the number of hospital discharges due to lower respiratory tract infections, were registered in a public pediatric hospital of Santiago. A respiratory virus surveillance (respiratory syncytial virus, adenovirus, influenza and parainfluenza virus) was done among children admitted for lower respiratory infections. Atmospheric temperature values and air pollution, measured as the number of particles of 10 microns or more per m3 (MP 10), were obtained from local health services.

RESULTS

Two elevation waves of outpatient consultations were detected at weeks 19 and 26, that coincided with the periods of maximal detection of influenza and syncytial respiratory virus, respectively. The epidemics of respiratory syncytial virus coincided with the maximal number of hospital admissions for lower respiratory tract infections at week 27. There was no correlation between air pollution and the number of pediatric consultations. The lower ambient temperatures coincided with the higher detection of respiratory syncytial virus at week 28, moment in which the demand for consultations or hospital admissions was descending.

CONCLUSIONS

There is a direct relationship between respiratory virus epidemics and the demand for pediatric consultations. There is also a minor influence of ambient temperature.

Prevalence of astrovirus infection among Chilean children with acute gastroenteritis

The frequency of astrovirus infection in 456 Chilean children with diarrhea was determined by enzyme-linked immunosorbent assay, reverse transcriptase PCR, and cell culture. Astrovirus was detected in 16.5% of rotavirus-negative and 7% of rotavirus-positive samples obtained from emergency rooms or hospitals and in 11% of samples from day care centers. HAst-1 was the predominant serotype identified.

Respiratory syncytial virus infection in infants is associated with predominant Th-2-like response

Viral infections have been associated with cellular immune responses and production of Th-1 cytokines. Respiratory syncytial virus (RSV), however, induces virus-specific IgE, which might be a consequence of a Th-2-like activation. To test this hypothesis we quantified interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) in the supernatant of peripheral blood mononuclear cells cultured for 24 and 48 h in the presence or absence of phytohemaglutinin and pokeweed mitogen and the lymphocyte phenotypes to analyze subsets and their activation markers, from 15 hospitalized infants during an acute lower respiratory infection caused by RSV and 17 healthy control infants from 1 to 15 mo of age. Compared with the control infants, those infected with RSV had an increase in the number of B-cells (p < 0.02) and decreases in both CD8+ T-cells (p < 0.01) and activated CD8+/CD25+ suppressor/ cytotoxic T-cells (p < 0.007). In RSV-infected infants, IFN-gamma production was subtotally suppressed, whereas IL-4 production was decreased to a lesser degree, giving significantly (p < 0.001) increased IL-4/IFN-gamma ratio compared with that in the control infants. These findings suggest a predominant Th-z-like response in RSV-infected infants, which could explain some aspects of the immunopathogenesis of RSV infection and the RSV-specific and nonspecific IgE antibody responses observed.

Discontinuation of antimicrobial therapy for febrile, neutropenic children with cancer: a prospective study

During a 2-year period, all children with cancer, neutropenia, and fever who were admitted to Hospital de Niños Luis Calvo Mackenna (Santiago, Chile) were enrolled in a study of the safety of stopping antibiotic therapy on day 3 of treatment. Children who met predefined criteria for nonbacterial fever were randomized on day 3 to stop (group A) or continue (group B) antibiotic therapy. A total of 220 children with cancer had 238 episodes of fever and neutropenia; 68 children with 75 episodes met entry criteria for nonbacterial fever (group A, 36; group B, 39). Both groups were comparable in terms of age, gender, oncological disease, chemotherapy status, and initial neutrophil count. Resolution of symptoms occurred in 34 of 36 episodes in group A and 36 of 39 episodes in group B (P > .05). No deaths occurred, and bacterial superinfections were uncommon. For children with cancer as well as episodes of fever and neutropenia without an identifiable bacterial etiology at admission, stopping antibiotic therapy on day 3 was safe and not associated with a higher risk of bacterial superinfections.

Molecular epidemiology of human rotaviruses in Santiago, Chile

BACKGROUND

Protective immunity against rotavirus infection is directed against antigenic epitopes on the outer capsid proteins VP7 and VP4. Our aim was to characterize the epidemiology of rotavirus antigenic types over time in Santiago, Chile.

METHODS

We prospectively obtained 2097 stool samples for rotavirus testing, VP7 (G1 to G4) and VP4 (P4, P6, P8, P9) typing from children with diarrhea evaluated in emergency rooms of 5 base hospitals of Santiago. In addition 256 rotavirus-positive samples collected between 1985 and 1987 in the north health care area of Santiago were studied.

RESULTS

Of 995 rotavirus-positive samples obtained 825 (82%) were typable for 1 or more VP7 types. G1 represented 81% of the G-typed samples during 1993 through 1995 and 77% during 1985 through 1987, predominating in all health care areas. G2 was next most common in all 5 areas, representing 6 to 23% of typed samples, with 1 area, the Southeast concentrating a significantly higher number of G2 infections. G2 declined from 35% of rotavirus-positive samples in 1993 to 0% in 1995 (P < 0.001), and from 25% to 2% in the north health care area from 1985 to 1987 (P < 0.001). G4 was uncommon and significantly more prevalent in 1985 through 1987 than in 1993 through 1995 (7% vs. 3%, P = 0.015). G3 was not detected. G1P8 (53%) and G2P4 (16%) combinations were by far the most commonly detected G-P associations.

CONCLUSIONS

In Santiago, Chile, rotavirus antigenic type G1P8 has been highly prevalent and G2P4 has circulated in cycles. Differences in epidemiology of rotavirus antigenic types worldwide may prove to be relevant in efficacy of rotavirus vaccines.

Treatment of respiratory syncytial virus infection with vitamin A: a randomized, placebo-controlled trial in Santiago, Chile

BACKGROUND

Treatment with high dose vitamin A reduces complications and duration of hospitalization for children with measles. In respiratory syncytial virus (RSV) infection, as with measles, low serum vitamin A concentrations correlate with increased severity of illness.

METHODS

To determine whether high dose vitamin A treatment is also effective for treating RSV disease, we conducted a randomized, double blind, placebo-controlled trial among 180 RSV-infected children between 1 month and 6 years of age at three hospitals in Santiago, Chile. Children with nasal washes positive for RSV antigen were given oral vitamin A (50,000 to 200,000 IU of retinyl palmitate, doses according to age; n = 89) or placebo (n = 91) within 2 days of admission.

RESULTS

There was no significant benefit from vitamin A treatment for the overall group in duration of hospitalization, need for supplemental oxygen or time to resolve hypoxemia. For the subgroup of children with significant hypoxemia on admission (room air oxygen saturation level < or = 90%), those given vitamin A had more rapid resolution of tachypnea (P = 0.01) and a shorter duration of hospitalization (5.5 vs. 9.3 days, P = 0.09). No toxicities were seen, including excess vomiting or bulging fontanel.

CONCLUSIONS

If vitamin A has a beneficial effect on the course of RSV disease, it may be seen only in more severely ill children.

Molecular epidemiology of adenovirus acute lower respiratory infections of children in the south cone of South America (1991-1994)

A collection of 165 adenovirus strains isolated from nasopharyngeal aspirates of children hospitalized for acute lower respiratory infection in Argentina, Chile, and Uruguay between 1991 and 1994 was studied by restriction enzyme analysis (work performed in the Department of Virology, University of Umeå). Of the isolates, 71% (n = 117) were identified as members of subgenus B. Of these, 101 (61.2%) corresponded to genome type 7h, four (2.4%) to genome type 3p2, four (2.4%) to genome type 11a, one (0.6%) to genome type 7b, and one (0.6%) to genome type 7c. Two isolates that were neutralized as serotype 3 and four isolates that were neutralized as serotype 7 exhibited novel BamHI cleavage profiles corresponding to three new genome types denominated 3x, 7i, and 7j. Subgenus C members represented 28.5% of all typed isolates. Five different genome types of Ad1, seven genome types of Ad2, and three genome types of Ad5 were identified of, which two, two, and one, respectively, were found to correspond to new DNA variants. Only one isolate (0.6%) corresponded to Ad4 of subgenus E. Ad7h was isolated from 17 of the 18 fatal cases recorded among the patients included in the study.

[Antigenic types of circulating rotavirus in children with acute diarrhea in Santiago de Chile]

Protective immunity against rotavirus infection is directed against antigenic epitopes on the outer capsid proteins VP7 and VP4. The aim of this study was to characterize the VP7 and VP4 antigenic types circulating in different hospital areas of Santiago, Chile, over different time periods. Between April 1993 and April 1994 a total of 1206 stool samples were obtained from children consulting for acute no bloody diarrhea in 5 hospitals representative of the 5 major health areas of Santiago. In addition, 256 rotavirus positive samples, obtained from children with acute diarrhea consulting in the north health area of Santiago between 1985-1987 were studied. All samples were processed for rotavirus by an ELISA and all rotavirus positive samples were VP7 typed (types G1-G4) by a monoclonal antibody based ELISA. 50 rotavirus positive samples were selected for VP4 typing by PCR (types P1-P4). A total of 782 rotavirus positive samples were obtained of which 618 (79%) were typable for one specific VP7 type. VP7 type G1 represented 63% of the rotavirus positive samples and predominated in all areas evaluated throughout the entire period of observation. VP7 type G2 represented 13% of rotavirus samples, following G1 in predominance. G2 types decreased progressively in all areas in both study periods. G4 types were detected mainly during 1985-1987, and G3 types have so far not been detected. Preliminary analysis of VP4 types suggests that P1 types are predominant and closely associated with VP7 G1 type. These results are relevant for the adoption of appropriate preventive strategies for rotavirus infection, specifically aimed to the development of effective vaccines.

Genome type analysis of Chilean adenovirus strains isolated in a children's hospital between 1988 and 1990

In a study designed to evaluate the genetic variability of adenovirus strains associated with infantile cases of respiratory disease requiring hospitalization, a collection of 136 adenovirus isolates obtained in the Roberto del Rio Children's Hospital of Santiago, Chile between June 1988 and November 1990 was studied by restriction enzyme analysis. Nasopharyngeal aspirates were obtained on admission from children under 2 years. During the study period a total of 227 adenovirus respiratory infections (ARI) were diagnosed at the ward for ARI by immunofluorescence, representing 23% of all admissions. Fifty percent of the 136 typed strains were found to belong to subgenus B, and the other 50% corresponded to subgenus C. Digestion with a set of seven enzymes allowed the identification of nine different genome types of subgenus C, three of which had not been previously described, exhibiting novel restriction patterns with either BgI II or BstEII. Ad7h, identified in 66 isolates, was the predominant genome type and was associated with the nine cases requiring mechanical respiratory assistance and with the two fatalities recorded during the 29 months. No differences were found between the age and sex distribution of subgenus B and C genomic variants, but the mean length of hospital stay (X +/- 2 SE) recorded among patients infected with subgenus B types was significantly higher (17.72 + 4.52 days (n = 55) vs. 7.54 + 1.70 days (n = 53); F = 17.22; P < 0.0001).

Genome type analysis of South American adenoviruses of subgenus C collected over a 7-year period

A collection of 148 adenovirus strains of subgenus C collected in Argentina, Chile, and Uruguay were studied by restriction enzyme analysis of genomic DNA with endonucleases BamHI, BglII, BstEII, EcoRI, HindIII, KpnI, and SmaI. Only strains corresponding to serotypes 1, 2, and 5 were identified representing both already described and new genome types. The most frequently detected type was Ad 2 followed by Ad 1 and Ad 5. Three different genomic variants of both Ad 1 and Ad 5 were discriminated. Ad 2 with 9 genome types exhibited the greatest variability. Novel profiles emerged only in strains corresponding to this serotype by restriction with BglII and BstEII. The circulation of prototype-like strains of Ad 1 throughout the study period is note-worthy. Thirty-six of 43 strains corresponded to genome type D 1. Clearly, one genome type of each serotype predominated over the 7-year period (Ad 1 D 1, n = 36; Ad 2 D 5, n = 32, Ad 5 D 36, n = 17). Some genomic variants were detected sporadically and only in Argentina, Chile, or Uruguay whereas others were widely distributed and circulated for years. A high proportion of the analysed strains was isolated from children under one year and males were more frequently infected than females.

Nosocomial transmission of rotavirus from patients admitted with diarrhea

We studied the transmission of rotavirus (RV) in 950 patients under 2 years of age hospitalized for diarrhea in Santiago, Chile. Stool samples were collected every other day from all patients during their entire hospital stay. To trace nosocomial transmission, we mapped the ward at the time of detection of RV. Comparative study by polyacrylamide gel electrophoresis of 315 RV isolates (180 detected upon admission of patients and 135 attributed to nosocomial transmission) allowed the identification of 18 different electropherotypes. An electropherotype similar to that of a community-acquired case was found in the same room in 81% of nosocomial cases and in the ward in 92% of nosocomial cases. It was concluded that the infants admitted shedding RV are the major source of nosocomial transmission and there was not a RV strain that was particularly transmissible.

Rotavirus detection by dot blot hybridization assay using a non-radioactive synthetic oligodeoxynucleotide probe

A synthetic oligodeoxynucleotide of 40 nucleotides corresponding to nucleotides 33-72 of the gene coding for the viral protein VP7 of rotavirus, was used as a nucleic acid probe to develop a non-radioactive hybridization method for rotavirus detection. The probe was labelled at the 3' end with biotin-7-dATP. The sensitivity and specificity of the dot blot hybridization assay for rotavirus detection was evaluated with 303 stool specimens. The results indicate that the hybridization assay has a higher sensitivity than both PAGE and EIA. Among the rotavirus strains tested 37 different electropherotypes were found. The results suggest that rotavirus diagnosis by dot hybridization using a non-radioactive probe may become routine laboratory procedure because it is simple, highly specific and very sensitive.

Community- and hospital-acquired respiratory syncytial virus infections in Chile

Nasopharyngeal aspirates were obtained on admission from 614 patients younger than 2 years of age who were hospitalized in a ward for acute respiratory infections from June 1988 through October, 1989, in Santiago, Chile. Patients in two rooms were followed during the cold seasons by sampling aspirates every other day during the child's entire hospital stay. Clinical features were recorded daily. Indirect monoclonal immunofluorescent assay and isolation in HEp-2 were used for respiratory syncytial virus (RSV) diagnosis. The mean RSV detection rate was 39% at the time of admission, ranging from 8% in April, 1989, to 62% in July, 1988. During the cold months 43 of 288 (15%) nosocomial RSV cases were detected. Pneumonia and wheezing bronchitis were the principal diagnoses of both groups admitted, whether they were shedding RSV or not. It is concluded that RSV plays a major role in admissions for acute respiratory infections, as well as in nosocomial infections, in Santiago. Because clinical features do not allow one to differentiate viral from bacterial acute respiratory infections, the importance of rapid viral diagnosis is emphasized.

Characterization of rotavirus electropherotypes excreted by symptomatic and asymptomatic infants

Human rotavirus isolates from 1100 stool samples were analyzed by polyacrylamide gel electrophoresis, and 48 different migration patterns were detected. Heterogeneity in the migration of segment 10 was observed in both long and short electropherotypes in which three long and two short patterns were identified. In spite of these variations all short and long electropherotypes were subgrouped by enzyme immunoassay as subgroups I and II respectively. Mixed infections were detected in 17% of cases and the subgrouping correlated with the corresponding electropherotypes. The same electropherotypes were present in severe, mild and asymptomatic cases and no electropherotype was particularly associated with greater virulence. Furthermore, the electropherotypes isolated from nosocomial asymptomatic cases were the same as those detected from those admitted with severe diarrhea. It seems unlikely that electropherotyping can be used to identify more virulent strains of rotavirus.

Dot hybridization assay for distinction of rotavirus serotypes

We have developed a hybridization assay that permits distinction of rotavirus serotypes 1, 2, 3, and 4. The serotype of rotaviruses from stool samples or tissue culture was recognized by hybridization of specific probes to (i) blots of viral double-stranded RNAs electrophoresed in agarose gels (Northern blots) or (ii) heat-denatured double-stranded RNAs directly dotted on nylon membranes. The probes consisted of 32P-labeled cDNA synthesized by reverse transcription of in vitro derived rotavirus mRNA from rotavirus serotypes 1 to 4. To prepare these probes, mRNAs were primed with a 17-mer nucleotide common to all four serotypes whose sequence is complementary to bases 375 to 391 of the rotavirus gene encoding the VP7 glycoprotein (gene 8 or 9 depending on the rotavirus strain). The resulting downstream transcripts encompassed areas of major sequence divergence among the four serotypes. Hybridization at high stringency (50 degrees C, 50% formamide, 4 x SSC [1 x SSC is 0.15 M NaCl plus 0.015 M sodium citrate]) was performed for 16 to 48 h. Autoradiograms of the washed membranes allowed recognition of the rotavirus serotype present in the blotted or dotted specimens since each of them hybridized preferentially to one of the four probes. Twenty-four laboratory specimens and 103 clinical specimens from Washington, D.C., Venezuela, and Chile were "serotyped" with this assay. The results were similar to those obtained with a monoclonal antibody serotyping assay.

In vitro transcription of human pararotavirus

Purified human pararotavirus obtained from stool samples from a 6-month-old infant was characterized. Electron microscopy of the viral particles subjected to different treatments suggested that the protein shells differed from those described for rotavirus. Treatment with both EDTA or ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid in the presence or absence of Mg2+ seemed to convert the virions into core particles by removal of both the outer and inner shells, and no particles equivalent to single-shelled rotavirus were observed. Different procedures were used to activate the human pararotavirus-associated RNA-dependent RNA polymerase. The enzyme was not activated by chelating agents or by thermal shock as in rotavirus. Activation by thermal shock occurred only in the presence of the four ribonucleoside triphosphates and Mg2+. However, the polymerase of pararotavirus was found to be similar to those described for rotaviruses. When in vitro transcripts were analyzed, 11 RNA species having a migration pattern similar to that of the original genomic RNA were detected.

Analysis of human rotavirus mixed electropherotypes

Mixed human rotavirus electropherotypes were detected in stool samples from patients with acute gastroenteritis in Santiago, Chile. These electropherotypes accounted for 10% of 149 samples studied. The finding of extra RNA fragments with respect to the regular 11 genome segments suggests the possibility of simultaneous or sequential infection by more than one electropherotype in a single diarrhea event or occurrence of modification in the length of the RNA segments during an infection. These possibilities arose from gel electrophoretic analysis of unique and sequential samples of human rotavirus genome RNA.

Rotavirus viral RNA electrophoresis in hospitalized infants with diarrhea in Santiago, Chile

Viral RNA electrophoresis technique was used to detect rotavirus in 226 children under 2 years of age with acute diarrhea, admitted to the Roberto del Río Hospital in Santiago, Chile, during the period of June 1979 through May 1980. A group of 50 children included in the aforementioned sample, admitted in winter, was compared with a control group of 25 infants without digestive pathology. In these groups, rotavirus was detected in 20 out of 50 children with diarrhea (40%) but not in the controls (0%). A positive diagnosis of rotavirus was found in 66 out of the total of 226 patients (29.2%); its monthly distribution ranged between a maximum of 83.3% (June) and a minimum of 11.1% (October).

Comparison of human rotaviruses isolated in Mexico City and in Santiago, Chile, by electrophoretic migration of their double-stranded ribonucleic acid genome segments

During the period October to December 1979, rotaviruses were obtained from infants and young children hospitalized with acute gastroenteritis in Mexico City and were compared by analysis of the migration of their double-stranded ribonucleic acid (RNA) genome segments in gel electrophoresis. Comparison of the results of this analysis and of those of similar studies carried out in 1977 and 1978 showed that the two rotavirus electropherotypes designated 2s and 21 have been continuously present and that the proportion in which these two types have been found in hospitalized patients has varied greatly year to year. The RNAs from rotaviruses 2s and 21 differed in the electrophoretic migraton of at least eight genome segments. However, RNAs from virus assigned to the same electrophoreotypes were not necessarily identical: on the basis of small but significant differences in the migration of segment 7, 8, or 9, isolates of types 2s and 21 could be assigned to two and three different subtypes, respectively. Human rotaviruses obtained in a distant geographical region, Santiago, Chile, in July 1979 had RNA electrophoretic patterns similar to that of electropherotype 21 but different from it in the migration of one or two of the larger RNA segments.

[Treatment of typhoid fever with chloramphenicol or ampicillin combined with oxyphenbutazone]

Ninety-four patients with typhoid fever were treated, at random, with three therapeutic regimens: chloramphenicol alone, chloramphenicol plus oxyphenbutazone, and ampicillin plus oxyphenbutazone. The results are evaluated analyzing the body temperature graph and by serial blood had bone marrow cultures taken at intervals until they became negative. Bacteriologic diagnosis was confirmed by blood culture (39.3%) and/or bone marrow culture (77%). The mean duration of fever was 3.3 days for the group treated with chloramphenicol-oxyphenbutazone, 4.3 for those with chloramphenicol alone and 5 days for the group ampicillin-oxyphenbutazone; at the same time, blood cultures became negative at 4.4, 5.5 and 4.4 days respectively. Negativization of bone marrow cultures was not influenced by the addition of oxyphenbutazone. It is concluded that the influence of oxyphenbutazone in shortening the febrile period or in the negativization of blood cultures is not significant. It is considered that oxyphenbutazone is not an important therapeutic tool in this group of diseases.