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.

Infection of mice with lactate dehydrogenase virus (LDV) leads to elevation of plasma lactate dehydrogenase, lifelong viraemia and perturbations of cell-mediated and humoral immune responses. The virus replicates exclusively in a restricted set of macrophages, but the basis for restricted cell susceptibility is unknown. By immunofluorescence techniques we have found that the per cent infected was the same as the per cent expressing antigens encoded by the I region of the major histocompatibility complex (Ia). Infection of CBA strain I-A+ peritoneal macrophages was blocked when cells were treated simultaneously with monoclonal antibody to I-A and I-E, but not with either antibody separately. LDV infectivity was inactivated when virus was treated with purified rat glycoprotein homologous to mouse I-A and I-E antigens. These results indicate that the receptors for LDV are I-A and I-E antigens. Selective infection of Ia-positive macrophages may have an important effect on the immunological capability of infected mice.

Subgenus C human adenoviruses, which include serotypes 1, 2, 5, and 6, are often associated with respiratory illness, ocular infections, gastroenteritis, and systemic infection among immunocompromised patients. To address the problems associated with the conventional typing methods, we developed a fiber-based multiplex PCR assay for simple and specific identification of adenovirus type 1, 2, 5, and 6 field isolates. To design type-specific primers, adenovirus type 1 and 6 fiber genes were sequenced. The assay correctly identified prototype strains of adenovirus serotypes 1, 2, 5, 6, as well as 21 previously typed adenovirus field isolates. Mixing two different prototype DNAs produced two amplicons of different lengths, thus clearly distinguishing the prototypes. The results correlated 100% with serological tests and 95% with the previously described PCR-restriction fragment length polymorphism method. The detection of dual infection is an added benefit of the assay. No nonspecific amplification was detected with other adenovirus serotypes or with nonadenoviral DNA. Our fiber-based multiplex PCR assay will provide a convenient tool for type-specific identification of subgenus C adenovirus isolates in various clinical situations and in epidemiological investigations and is a better alternative than the hexon-based assay.Fifty-one serotypes of human adenoviruses (Ads) have been divided into six subgenera, A through F, based on various biological and morphological criteria (9, 28). The members of subgenus C, Ad1, Ad2, Ad5, and Ad6, are the most frequently isolated human Ads, accounting for 59% of all Ad infections (27). Respiratory infections caused by these Ads may be indistinguishable from infections caused by other respiratory pathogens, such as influenza, parainfluenza, and respiratory syncytial viruses as well as certain bacteria (12). These Ads are the causative agents of pharyngeal conjunctival fever among children as well as of outbreaks of conjunctivitis related to swimming pools during the summer (4). Ad2 is the predominant serotype, next to Ad40 and Ad41, related to enteric infections among young children (11,18,24). In addition to diarrhea, subgenus C Ads are also linked to intussusception of the intestine caused by Ad-infected mesenteric lymph nodes (3,7,21). They are also the serotypes predominantly isolated among immunosuppressed patients and are responsible for fatal infections of transplant recipients (16,19). Furthermore, subgenus C Ads seem to be associated with sudden infant death syndrome (2). Therefore, identification of the serotypes mentioned above is very important under different clinical conditions and in epidemiological studies.Conventional methods for typing of Ads are usually based on neutralization (NT) and/or hemagglutination inhibition (HAI) assays, which are not only cumbersome but also timeconsuming (14,15,17,25). Restriction endonuclease analysis (REA) of DNA extracted from infected cells, although proven to be epidemiologically valuable, requires technical skill and time and ther...

In 1996, three adenovirus type 7 (Ad7) strains were isolated from children with fever and upper respiratory diseases in Japan. Restriction endonucleases (REs) analysis and PCR amplification of the E3 7.7 kDa ORF revealed that these strains were genotype Ad7h and closely related to an Argentine Ad7h strain, which has been reported to be highly virulent and so far predominant only in South America. These strains showed weak cross-neutralizing activity and specific haemagglutination-inhibition activity to Ad3 antiserum. The present findings suggest that Ad7h in South America has spread to other parts of the world. Since the seroprevalence to Ad7 in the current Japanese population is very low due to the absence of Ad7 circulation in Japan for decades, Ad7 outbreak as a typical case of re-emerging infectious diseases is a cause for serious concern.

Lactic dehydrogenase virus (LDV) infected cells were localised in cryostat sections of infected adult and suckling mice by fluorescent antibody staining. In almost every organ except brain and spinal cord, LDV infected cells were present in interstitial connective tissue, including dermis and submucosa of gastrointestinal and urinogenital tracts. They were also present in liver sinusoids and red pulp of spleen. The tissue distribution, shape, and fluorescence staining pattern of infected cells were similar in adult and suckling mice. The reactivity with monoclonal antibody to mouse macrophages (F4/80) and to Ia antigens indicated that infected cells were Ia antigen positive macrophages, and this was confirmed in double labelling experiments. Peak numbers of LDV infected cells were seen in every organ 12-18 hours post infection (p.i.), disappearing rapidly thereafter until at 48 hours p.i. they could no longer be detected. At the same time Ia positive cells fell to undetectable levels, although macrophages were still present in reduced numbers. At 7 days p.i. the total number of macrophages in sections had returned to normal, but the number of Ia positive cells remained at low levels. Macrophages recovered from peritoneal cavity and spleen of intraperitoneally infected mice were also studied. Ia positive cells had virtually disappeared from peritoneal cavity at 24-48 hours, and from spleen at 24-72 hours. Three weeks after infection the proportion of Ia positive cells was still low when compared with that of normal mice suggesting selective loss of these cells.