Genome type analysis of adenovirus types 3 and 7 isolated during successive outbreaks of lower respiratory tract infections in children

Adenovirus is an important cause of respiratory infections in infants and children. Fifty-one serotypes have been identified, and adenovirus type 3 (Ad3) and Ad7 have often been associated with outbreaks of severe respiratory tract infections. Each serotype can be further divided into genome types based on the patterns of digestion of their DNAs with restriction enzymes. DNA restriction analysis was performed with 56 strains of Ad3 and 98 strains of Ad7 by using 12 restriction enzymes recognizing 6 bp (BamHI, BclI, BglI, BglII, BstEII, EcoRI, HindIII, HpaI, SalI, SmaI, XbaI, and XhoI). The virus strains were isolated during outbreaks of lower respiratory tract infections in children during an 11-year period from 1990 to 2000 in Seoul, Korea. Among the Ad3 strains, seven genome types were identified; Ad3a and six novel types (Ad3a13, Ad3a14, Ad3a15, Ad3a16, Ad3a17, and Ad3a18). Multiple genome types cocirculated during outbreaks, and some of these were isolated during the 11-year observation period, while others were restricted to particular outbreaks. For Ad7, two genome types, Ad7d and Ad7l, the latter of which is a novel genome type, were identified. A shift in genome types occurred from Ad7d to Ad7l during successive outbreaks. Mortality was 3.6% among children with Ad3 infections and 18% among children infected with either of the Ad7 genome types. In conclusion, the data confirm that Ad3 genome types are more diverse than those of Ad7 and suggest that shifts of genome types may occur during successive outbreaks of Ad3 and Ad7.     

Molecular epidemiology of two consecutive outbreaks of adenovirus 8 keratoconjunctivitis

Eleven strains of adenovirus 8 (Ad 8) isolated during two consecutive outbreaks of epidemic keratoconjunctivitis (EKC) in the Ophthalmology Department of a University Hospital in France were compared by DNA restriction analysis. The results indicated that isolates from the two outbreaks belong to the same genome type, which is also the most predominant genome type of Ad 8. The usefulness of molecular epidemiology in Ad 8 infections is briefly discussed.     

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.     

New genome types of adenovirus types 1, 3, and 5 isolated from stools of children in Brazil.

During an epidemiological survey made in S?o Paulo (Brazil), fecal specimens were periodically collected from 100 randomly chosen babies from birth to the age of 18 months. The stools, routinely collected each month and also collected each time a child presented any sign of disease, were screened for the presence of adenoviruses. Sixteen adenovirus strains, isolated from the stools of healthy and ill children, were characterized by restriction enzyme analysis. Five isolates were from subgenus A, five were from subgenus B, four were from subgenus C, and two were from subgenus D. All but two showed some restriction patterns different from those of the 42 human adenovirus prototypes and all the genome types described up to now. No fastidious adenovirus (subgenus F, serotypes 40 and 41) was encountered in the stools examined. We report here the restriction enzyme analysis of isolates of subgenera B and C. The following new designation genome types are proposed: Ad3e1 (subgenus B) and Ad1d, Ad5a1, and Ad5a2 (subgenus C).     

PCR analysis of egyptian respiratory adenovirus isolates, including identification of species, serotypes, and coinfections

Eighty-eight adenovirus (Ad) isolates and associated clinical data were collected from walk-in patients with influenza-like illness in Egypt during routine influenza surveillance from 1999 through 2002. Respiratory Ad distributions are geographically variable, and serotype prevalence has not been previously characterized in this region. Serotype identity is clinically relevant because it predicts vaccine efficacy and correlates strongly with both clinical presentation and epidemiological pattern. Species and serotype identities were determined using several well-validated multiplex PCR protocols culled from the literature and supplemented with a few novel primer sets designed to identify rare types. The isolates included common species B1 serotypes (Ad3 and Ad7), common species C serotypes (Ad1, Ad2, and Ad5), the less common species B2 serotype Ad11, and three isolates of the rare species B1 serotype Ad16. Two isolates that appear to be variant Ad16 were also identified. Fifteen coinfections of multiple adenoviral types, primarily AdB/AdC and Ad3/Ad7 dual infections, were detected. The majority of these were verified using redundant PCR tests targeted at multiple genes. PCR is able to resolve coinfections, in contrast to traditional serum neutralization tests. PCR is also comparatively rapid and requires very little equipment. Application of the method allowed an inclusive determination of the serotypes found in the Egyptian respiratory sample set and demonstrated that coinfections are common and may play a previously unrecognized role in adenovirus pathogenesis, evolution, and epidemiology. In particular, coinfections may influence adenoviral evolution, as interserotypic recombination has been identified as a source of emerging strains.     

7株B亚属人腺病毒纤维基因特征分析

目的 了解本实验室2004-2006年分离的7株B亚属腺病毒(adenovirus,Ad)的纤维基因特征,并与日本、韩国腺病毒分离株的纤维基因进行比较.方法 2004-2006年间,本实验室从上呼吸道感染儿童散发或暴发病例中分离到7株腺病毒毒株,首先对六邻体蛋白基因扩增和序列分析进行基因分型,随后用PCR扩增纤维蛋白基因,进行序列测定,构建亲缘性关系进化树,并对其基因特征进行分析.结果 7株腺病毒分离株均属于B亚属,其中有3株为Ad3型,所测定的纤维蛋白基因的核苷酸同源性为98.9%～100%,与2003年中国广州分离株DQ099432和2003年韩国分离株AY224416的同源性为100%;3株为Ad7型,纤维蛋白基因核苷酸同源性为97.6%～100%,与2006年日本分离株AB243119的同源性为97.4%,与2000年韩国分离株AY921620的同源性为100%;1株为Ad11型,与GenBank序列号为L08232的1993年瑞典分离株纤维蛋白基因同源性为100%.结论 2004-2006年,北京地区上呼吸道感染散发病例,Ad3和Ad7纤维基因核苷酸变异不大,同时证实本研究用纤维基因片段,与六邻体基因分型具有相同的结果.     

PCR and restriction endonuclease analysis for rapid identification of human adenovirus subgenera

Subgenus identification of adenoviruses is of clinical importance and is as informative as identification by serotype in most clinical situations. A PCR-based identification of adenovirus subgenera A, B, C, D, E, and F and sometimes serotypes is described. The PCR uses nonnested primer pair ADRJC1-ADRJC2, which targets a highly conserved region of the adenovirus hexon gene, has a sensitivity of 10 to 40 copies of adenovirus type 2 (Ad2) DNA, and generates 140-bp PCR products from adenovirus serotypes representative of all the subgroups. The PCR products of all subgroups can be differentiated on the basis of the restriction fragment patterns produced by a total of five restriction endonucleases. In addition, serotypes Ad40 and Ad41 (subgroup F) and important serotypes of subgroup D (Ad8, Ad10, Ad19, and Ad37) can easily be differentiated, but serotypes within subgroups B and C cannot. The method was assessed by blind subgenus identification of 56 miscellaneous clinical isolates of adenoviruses. The identities of these isolates at the subgenus level by the PCR correlated 91% (51 of 56) with the results of serotyping by the neutralization test, and 9% (5 of 56) of clinical isolates produced discordant results.     

Secular trend of genome types of respiratory adenovirus type 3 during 1983–2005: a study from Taiwan

Genome type analysis of adenovirus type 3 (Ad3) in Taiwan identified four types (Ad3a, Ad3a2, Ad3a1, Ad3–7) during 1983–2005. Ad3a was the major type during 1983–1999, while Ad3a2 was the predominant type from 2001 to 2005. Phylogenetic analysis of the hexon gene of 23 isolates revealed that most Ad3a2 and Ad3–7 isolates belonged to one cluster, and most Ad3a isolates to the other cluster. The clinical manifestations included respiratory tract infections, acute gastroenteritis, hand-foot-and-mouth disease, febrile convulsion and pharyngoconjunctival fever. In conclusion, Ad3a2 has replaced Ad3a as the most common genome type in Taiwan since 2001.     

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 Bgl 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) © 1994 Wiiey-Liss, Inc.     

A community-derived outbreak of adenovirus type 3 in children in Taiwan between 2004 and 2005

An outbreak of respiratory adenovirus infection in children was observed in northern Taiwan between November 2004 and February 2005. Using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) to determine the serotype(s) of 172 adenovirus isolates in the outbreak period, we found that adenovirus type 3 (Ad3) was the predominant type (87.2%), followed by Ad2 (6.4%), Ad1 (4.1%), Ad7 (1.2%), Ad4 (0.6%), and Ad5 (0.6%). The genotype of Ad3 was analyzed for 15 isolates from the outbreak period by RFLP of the full-length genome. All these isolates belonged to genotype Ad3a2. Compared with the Ad3-infected patients in the baseline period, a significantly higher proportion of Ad3-infected patients in the outbreak period had severe infections (58.0% vs. 40.2%, P = 0.01), which included bronchopneumonia (28.7%), exudative tonsillitis (24.1%), and tonsillitis (16.1%). Moreover, patients with severe infections were significantly younger than those without (4.10 vs. 8.15 years, P < 0.001). In summary, our study demonstrated that Ad3 was the predominant serotype responsible for the respiratory adenovirus outbreak in northern Taiwan during 2004-2005 and was associated with severe infections in the outbreak period.     

Silver staining of DNA restriction fragments for the rapid identification of adenovirus isolates: application during nosocomial outbreaks

The ultrasensitive photochemical silver stain for nucleic acids, described by Beidler et al. (1982), has been applied to the detection of adenovirus restriction fragments as a relatively rapid technique for the identification of virus isolates. In this study, restriction enzyme cleavage analysis was used to characterize adenovirus isolates from what appeared to be two nosocomial outbreaks. The first outbreak was thus shown to include two clusters of patients, and involved two serotypes Ad7c and Ad40. The second outbreak was unrelated and involved Ad35. Although restriction analysis does not replace serum neutralization as a routine method for typing adenoviruses, it is a much more rapid means of discriminating between different patient isolates, providing a current rather than retrospective analysis of a nosocomial outbreak. During the first outbreak, restriction analysis identified two distinct adenovirus serotypes from one patient--Ad7c from a nasopharyngeal aspirate and Ad41 from a stool specimen. Restriction analysis is also valuable for the sub-typing of virus isolates. In this study, the Ad40 and Ad41 isolates were shown to be variants of the respective prototype strains.     

Rapid detection and serotyping of adenovirus by direct immunofluorescence

Four fluorescent antibody reagents were evaluated for their suitability for the identification of adenovirus isolates by immunofluorescence. The antibodies used in the reagents consist of monoclonal antibodies against adenovirus type 3 (Ad3), Ad4, Ad8, and adenoviruses of subgroup C (Ad1,2,5,6), serotypes known to occur in outbreaks of disease. Most of the monoclonal antibodies employed were reactive against type-specific antigens found on the hexon protein. Reagents employing two noncompeting anti-hexon antibodies were more sensitive than reagents prepared with only one monoclonal antibody, although both types of reagents exhibited a high degree of specificity. Five hundred and seventeen adenovirus isolates (359 of which had previously been typed by other methods) and 46 nonadenovirus isolates were examined with all four type-specific reagents in parallel with an adenovirus group-specific reagent. The results indicate that direct typing of adenovirus isolates is feasible, leading to significant savings in time compared to other typing methods and should contribute to the management of certain adenovirus infections, particularly during outbreaks. J. Med. Virol. 51:198–201, 1997. © 1997 Wiley-Liss, Inc.     

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. © 1996 Wiley-Liss, Inc.     

Molecular epidemiology of adenovirus types 3 and 7 isolated from children with pneumonia in Beijing

One hundred fifty strains of adenovirus serotypes 3 (Ad3) and 7 (Ad7) were analyzed. The viruses were isolated from patients, the majority of whom had pneumonia, from central and suburban Beijing over a 33-year period (1958–1990). Genomic analysis of DNA extracted from 74 strains of Ad3 and 76 strains of Ad7, with four to five restriction endonucleases (REs), revealed the presence of four and eight genome types, respectively: Ad3a2, Ad3a4, Ad3a5, Ad3a6 and Ad7p1, Ad7a1, Ad7a4, Ad7b, Ad7b1, Ad7d, Ad7d1, and Ad7g. Ad7b1 was the most recently identified genome type. The restriction patterns obtained from 19 representatives of Ad7 genome types after cleavage of the DNA with 12 REs are shown. Ad3a2 first appeared in 1962, and predominated from 1983 to 1988. Ad3a4 was the main causative agent of pneumonia in 1982. Ad3a2 and Ad3a4 are closely related and have 97% pairwise comigrating restriction fragments (PCRF). Ad7d predominated over a period of 11 years (1980–1990). It has 98% PCRF with Ad7b. Ten pairs of strains isolated from different specimens of the same patients were all concordant. © 1996 Wiley-Liss, Inc.     

Demonstration of three different subtypes of adenovirus type 7 by DNA restriction site mapping.

Restriction site mapping of the genomes of eight different isolates of adenovirus serotype 7 (Ad7) has been performed with six different restriction endonucleases. In this analysis, 37 different restriction sites were localized. Three distinctly different cleavage patterns of the genomes of the Ad7 strains were observed. These strains could not be distinguished by serological techniques. The following three subtypes were defined on the basis of their restriction site patterns: the Ad7 prototype, represented by strain Gomen originally isolated from a case of pharyngitis; subtype Ad7a, represented by the Ad7 vaccine strain and strains isolated from undifferentiated respiratory disease and from a healthy carrier; and a third subtype of Ad7, represented by three strains which were isolated from Swedish patients, all having pronounced clinical symptoms indicating severe systemic infection. A comparison of the restriction site maps of the protype of Ad3 and the three subtypes of Ad7 indicated greater differences in the position of restriction sites between strains of Ad7 than between strains of the two serotypes. This technique is consequently recommended to obtain a more precise definition of distinct entities of viruses.     

Molecular epidemiology of adenoviruses associated with acute lower respiratory disease of children in Buenos Aires, Argentina (1984-1988).

DNA restriction analysis was carried out on a sample of 73 adenovirus strains isolated in Buenos Aires from nasopharyngeal aspirates of children with lower acute respiratory infection between 1984 and 1988. Thirty-five isolates (47.9%) were classified as members of subgenus B. Of these, three were identified as a new genome type of Ad3p denominated Ad3p3; five strains corresponded to genome type 7b and two to genome type 7c. The other 25 isolates were identified as the recently recognized genome type 7h. All 6 fatalities recorded within this group of 73 children were associated with infection by Adenovirus genome type 7h. Thirty-seven isolates (50.7%) were classified within subgenus C that corresponded to 9 different genome types denominated 1p (n = 5); 1# (n = 2); 2p (n = 4); 2b (n = 6); 2# (n = 5); 5# (n = 4); 5* (n = 7) and 5+ (n = 2). All genome types of subgenus C were compared with the data reported by Adrian et al. (Archives of Virology 112:235-238, 1990). The Ad1p and Ad1# genome types could be allocated to AV1 genome types D1 and D10, respectively. Ad2b genome type could be allocated to AV2 genome type D25. No counterparts were found for the remaining 6 genomic variants. Only one isolate was identified as Ad4a of subgenus E. The comparison of the results of the present study with those of the molecular characterization of Chilean strains isolated between 1984 and 1987 suggests that the adenovirus strains associated with respiratory disease of children may be common in both countries.     

Subtypes of bovine adenovirus type 2 exhibit major differences in region E3

The genomes of two adenovirus type 2 strains which were isolated from different hosts have been investigated. One of these strains designated ORT-111 was originally isolated from a lamb in Hungary during an outbreak of pneumoenteritis. This isolate was typed as bovine adenovirus type 2 (Ad bos 2) in a neutralization assay. The genome of ORT-111 was compared to that of the prototype strain of Ad bos 2, a virus which exclusively has been isolated from cattle. Electron microscopic heteroduplex analysis showed that 95% of the genomes were well matched, forming stable duplexes at Tm -6 degrees. Two distinct substitution loops were, however, seen which were approximately 0.5 and 1.0 kbp long. The centers of the two loops were located 5.3 and 7.7 kbp from one end of the Ad bos 2 genome. In order to map these regions relative to the gene map of human adenovirus type 2 (Ad2), restriction enzyme cleavage fragments of the two bovine viruses were cloned and hybridized to different sets of restriction fragments of human Ad2. From these results it was apparent that the centers of the two substitution loops were located at coordinates 76 and 83, respectively; thus at positions which fall within region E3 and the adjacent gene for polypeptide VIII of human Ad2. The observed differences between the genomes of the two Ad bos 2 strains are in sharp contrast to those previously observed when the genomes of different human adenovirus serotypes were compared. In the latter case the hexon and the fiber genes showed the most pronounced variation.     

Molecular epidemiology of adenovirus strains isolated from patients with ocular disease in the area of Thessaloniki, Greece (1998-2002)

Thirty strains of adenovirus (Ads) associated with ocular disease have been isolated over a period of 4 years in Thessaloniki, Northern Greece. Eleven strains were isolated from sporadic patients with conjunctivitis or keratoconjunctivitis in Thessaloniki city between 1998 and 2000. Nineteen strains were isolated from patients with keratoconjunctivitis during an outbreak of Ads in the area of Thessaloniki (Thessaloniki and Serres cities) in 2002. PCR-sequence method using primers targeted against the hypervariable regions (HVRs) of hexon gene, as well as the neutralization test were used for typing the Ad isolates and assessing a possible relation among these strains, and their genetic variability. Ad4 with very close homology to variant Z-G 95-873 was the most frequent genotype causing sporadic conjunctivitis over a period of 4 years. Two other strains, one Ad2, and one Ad3 were similar to the prototype ones, and a third one shows close homology to the variant of prototype Ad15, the Morrison strain. The genome typing of twenty two Ad8 isolates showed very close homology in their amino acid and nucleotide sequences to the variant of Ad8, strain 1127 (accession no. X74663). Four were isolated from patients with keratoconjunctivitis in 1998, 1999, 2000 and 18 during the outbreak in 2002. As far as strain 1127 is concerned, all the Ad8 isolates showed the same changes in the HVR 1 and HVR 2 except one isolate in 1998, which showed some changes outside the HVRs. During the outbreak of Ad8 keratoconjunctivitis, it was not possible to identify the exact source of infection (nosocomial or/and outpatients). Finally, Ad4 variant Z-G 95-873 and Ad8 which is closely related to the strain 1127, were found to be the predominant adenoviruses circulating in Northern Greece during 1998-2002.     

Genetic variability of hexon loops 1 and 2 between seven genome types of adenovirus serotype 7

Summary.  In order to understand the evolutionary relationships between different genome types of adenovirus serotype 7, the nucleotide sequences of the hexon loops 1 and 2 from seven genome types have been determined. Their amino acid sequences comprising 473 to 476 residues were consequently analysed. The pairwise comparison of the sequences from seven genome types revealed the existences of two genome type clusters (GTCs). GTC1 includes Ad7p and Ad7p1, and GTC2 contains Ad7b, Ad7c, Ad7d, Ad7g and Ad7h. The amino acid similarity was 98.3–99.8% within a cluster and 93.0–94.5% between two clusters. However, the average amino acid similarity among 16 different human adenovirus serotypes was only 65% with two exceptions, 92.7% between Ad4 and Ad16, and 86.8% between Ad3 and Ad7. Two variable regions were found in the loops 1 and 2. A deletion of nine nucleotides was detected in the variable region 1 of all members of GTC2. According to the alignment of nucleotide sequences, two short direct repeats were found at the deletion junctions, indicating that GTC2 may be derived from GTC1 by illegitimate recombination. In variable region 2, the substitution from 443Leu (Ad7b) to Gln (Ad7d) dramatically affected the hydropathic characters of this region. The region surrounding 443Leu (Ad7b) manifested hydrophobicity whereas the region surrounding Gln (Ad7d) manifested hydrophilicity. Received June 22, 1998 Accepted April 19, 1999     

Ten-year analysis of adenovirus type 7 molecular epidemiology in Korea, 1995-2004: implication of fiber diversity.

BACKGROUND: Adenovirus type 7 (Ad7) is frequently responsible for severe respiratory infections, especially in young infants. Since the Ad7 epidemics have been associated with severe childhood pneumonia and significant mortality in Korea, 1995-1999, continuous surveillance was necessary for Ad7 related diseases. OBJECTIVES: To characterize epidemiologic features of Ad7 in 1995-2004, genetic diversity of Ad7 were studied by determining genome types (GTs) and the fiber diversity. STUDY DESIGN: A total of 139 Ad7 strains were obtained from Korean children with pneumonia. Serotype specificity was confirmed by microneutralization assay. GTs were determined by restriction analysis with 12 enzymes. The variable region of the fiber was sequenced. RESULTS: Two GTs, Ad7d (N=98, 71%) and Ad7l (N=41, 29%) have been identified. In 1995-1996 and 2001-2002, Ad7d was dominant accounting for 98-100% of all Ad7; in 1999-2000, Ad7l was the prevalent GT accounting for 100% of all Ad7; in 1997-1998 and 2003-2004, both GTs circulated concurrently. The change in the relative predominance of GT occurred in 2 or 3 years. The Lys substitution for Arg at codon 280 of the fiber was identified in 31 Ad7d strains (32%) while no variations were observed among Ad7l. It was noteworthy that two fiber variants of Ad7d were not concurrently prevalent on any time after 1996. The shift in predominant fiber variants of Ad7d was also observed in 2-3 years. CONCLUSIONS: Our data demonstrated that the two GTs, Ad7d and Ad7l circulated in an alternating manner between outbreaks of Ad7 associated childhood pneumonia over 10 consecutive years in Korea. Fiber diversity at position 280 within Ad7d appeared to contribute to the annual distribution of Ad7d. This observation necessitates further studies to demonstrate an association between fiber variation and host cell specificity or neutralization antibody recognition.