Adriana E. Kajon

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.

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°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. J. Med. Virol. 60:342–346, 2000.

Adenovirus type 7h respiratory infections: a report of 29 cases of acute lower respiratory disease

Twenty‐nine cases of pediatric acute lower respiratory disease associated with adenovirus genome type 7h were evaluated retrospectively. They constituted 2.4% of 1233 cases of acute respiratory infections treated in five hospitals in Buenos Aires, between September 1984 and September 1988. Pneumonia and bronchiolitis were the principal diagnoses. The mean age of patients was 8.8 months and 82.7% of the children were less than one year of age. None of the patients had previously been exposed to measles or was immunocompromised. A mixed infection, viral or bacterial, was demonstrated in 8 of the 29 patients. Sixteen children developed a severe pulmonary disease which required intensive care. Ten with a clinical diagnosis of multifocal pneumonia and necrotizing bronchiolitis died. Extrapulmonary manifestations were observed in the most severe cases. Observations suggest a possible high pathogenicity of adenovirus type 7h and emphasize the need for adequate control and case management programs.

Genomic analysis of adenovirus isolated from Argentinian children with acute lower respiratory infections

BACKGROUND Adenoviruses are the second cause of acute lower respiratory infection (ALRI) of viral origin in small children from Buenos Aires, Argentina. OBJECTIVE The aim of this study was to characterize, by restriction enzyme analysis, 17 adenovirus strains isolated from the nasopharyngeal aspirates of children under 2 years of age hospitalized due to ALRI. STUDY DESIGN Seventeen adenovirus strains isolated between May 1991 and December 1992 in one hospital of Buenos Aires were studied. Adenoviruses were amplified in HEp-2 cells and viral DNA was studied with the restriction enzymes Bam HI and Sma I. RESULTS AND CONCLUSIONS Eighty two percent (14/17) of the isolates were classified as adenoviruses from subgenus b and 17.7% (3/17) belonged to subgenus c. Genome type 7 h was detected in 85.7% (12/14) and 7 i in 14.3% (2/14) of the strains from subgenus b. The case lethality associated with adenovirus genome type 7 was 28.6% (4/14 cases). Three fatal cases corresponded to Ad 7 h and one to Ad 7i. Ad 7h shows a high prevalence in small children hospitalized with ALRI and is associated with a high fatality rate.

Fatal adenovirus infection associated with new genome type.

The first fatal case caused by the new genome type 7i is described in an 8‐month‐old boy requiring long‐term respiratory support who developed Reyes syndrome, acute respiratory distress, and bronchiolitis obliterans with fatal evolution. Adenovirus was detected in nasopharyngeal secretions and was persistently positive during hospitalization. IgM and IgG adenovirus antibody titers measured in serum by enzyme‐linked immunoassay (EIA) were 1:32 and 1:800, respectively. Serum interleukins (IL) and interferons (IFN) measured by EIA were as follows: IL‐2, 110 pg/ml; IL‐6, 300 pg/ml; IL‐8, 7,000 pg/ml; TNF‐α, 35 pg/ml, IL‐1 and IL‐4 undetectable, IFN‐α 2,200 pg/ml, and IFN‐γ 700 pg/ml. Virologic studies showed that adenovirus isolated belonged to subgenus B, and digestion of viral DNA with Bam HI, Sma I, Bgl II, and Hind III identified the isolate as belonging to genome type 7i. Autopsy showed bronchiolitis obliterans with diffuse alveolar damage and perivenular fatty degeneration with polymorphonuclear infiltrates in the periportal spaces. The difficulty in obtaining adequate oxygenation with minimization of iatrogenic oxygen injury is discussed.J. Med. Virol. 54:233–236, 1998.

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

SummaryA collection of 148 adenovirus strains of subgenus C collected in Argentina, Chile, and Uruguay were studied by restriction enzyme analysis of genomic DNA with endonucleasesBam HI,Bgl II,Bst EII,Eco RI,Hind III,Kpn I, andSma I. 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 withBgl II andBst EII. The circulation of prototype-like strains of Ad 1 throughout the study period is noteworthy. 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, and 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.

Characterization of adenovirus genome type 7h: analysis of its relationship to other members of serotype 7.

Ad7h is a newly identified genome type associated with severe lower acute respiratory infections and has so far been isolated only in South America. To obtain a clue to its possible origin, the degree of restriction enzyme site homology between adenovirus genome type 7h and those representative of the three described genomic clusters (GC) for serotype 7 was studied by analysis of pairwise comigrating DNA restriction fragments (PCRF) after digestion with BamHI, BglI, BglII, BstEII, EcoRI, HindIII, HpaI, SalI, SmaI, XbaI, and XhoI. The most closely related genome types, Ad7b, Ad7d, and Ad7g, displayed 85.7, 83.8, and 82.8% comigrating fragments, respectively. Ad7p (GC1) was clearly distant with only 68.6% PCRF. No remarkable close genetic relationships (%PCRF greater than 90) were observed with any of the genome types grouped within GC3 or with Ad7g (the only member of GC2), so since Ad7h seems to be related to both members of GC2 and GC3, it could equally be considered to represent a new cluster or to end up grouped in either GC2 or GC3, depending on the results of further analysis.

Genome type analysis of Brazilian adenovirus strains of serotypes 1, 2, 3, 5, and 7 collected between 1976 and 1995

A collection of 92 epidemiologically unrelated isolates of Ad1 (n = 14), Ad2 (n = 29), Ad3 (n = 19), Ad5 (n = 16), and Ad7 (n = 14) collected in the cities of Belem do Pará (1°S 48°W) and Rio de Janeiro (23°S 43°W) between 1976 and 1995 from patients with respiratory disease and conjunctivitis were characterized by restriction enzyme analysis of genomic DNA. Among the strains of subgenus B, two different genome types of serotype 7, 7b and 7e, were identified. The analysis of their temporal distribution throughout the study period suggested an alternating appearance of these two DNA variants. Only one genome type of Ad3, 3p, was detected during the sampling period. Further analysis with Xba I, Bcl I, and Hpa I indicated that it is a p1‐like genome type. Both previously described and new genomic variants were identified among subgenus C strains. Genome types D1, D7, D10, and one not previously described were identified among the 14 Ad1 strains analyzed. Genome types D2, D5, D25, and 13 new DNA variants were identified among the 29 Ad2 isolates. Genome type D38 and 5 new variants were found among the 16 strains of Ad5. In spite of the relatively small size of the sample analyzed, the results of this study confirm the important genetic variability previously observed for members of subgenus C by other authors. J. Med Virol. 58:408–412, 1999.

Lymphocyte subsets and cytokines in adenoviral infection in children

To determine the distribution of major blood lymphocyte subsets we evaluated blood lymphocytes by flow cytometry in adenovirus‐infected infants aged 30–730 d. In addition, interleukin‐1‐receptor antagonist, interleukin‐10 and transforming growth factor‐β1 were measured in serum by enzyme‐linked immunosorbent assay. According to clinical parameters, mechanical ventilation and outcome, infections were classified as moderate (n= 15), severe (n= 11) and fatal (n= 12). Controls were 13 healthy children. In severe and fatal infection, T cells (CD5+/CD19‐), NK effectors (CD16+), CD4+ T subset and B1 subset of B lymphocytes (CD5+/CD19+) were all significantly decreased. CD8+ cells were decreased in severe but not fatal cases. There was no difference in serum values of interleukin‐10; however, fatal cases had high interleukin 1‐receptor antagonist values. Interestingly, patients with moderate infection showed significantly increased values of transforming growth factor‐β1. These results demonstrate that life‐threatening adenoviral infection is associated with marked abnormalities in blood lymphocyte and cytokine profile.