Detection of adenovirus by rapid 24-well plate centrifugation and conventional cell culture with dexamethasone

Evaluation of rapid culture centrifugation method for adenovirus detection in stools

Routine laboratory testing for adenovirus (Adv) requires a procedure that is rapid and reliable, especially for samples from children and immunosuppressed patients, when diarrhea may signal the onset of severe gastrointestinal disorders. An improved culture technique for Adv isolation, using centrifugation step of 24-well plates and needing only 48 h incubation, was evaluated for 382 stool samples. This technique was compared with conventional tube cell culture and a commercial enzyme-linked immunosorbent assay (ELISA) kit. Adv was isolated in 36 samples (9.4%) by rapid culture, in 32 (8.4%) by conventional culture, and in 42 samples (11%) using genus-specific ELISA. A total of 30 isolates were found to be Adv positive in both rapid and conventional cultures, and half of the Adv-positive rapid culture isolates were identified as serotypes 40/41 using a type-specific ELISA. The improved culture method considerably reduces incubation time and also offers a slightly enhanced sensitivity to Adv serotypes. Combined with appropriate cell lines adapted to the isolation of enteric adenoviruses, it therefore constitutes a valuable laboratory test particularly useful in the diagnosis of gastroenteritis.

Enteric prevalence of adenovirus in human immunodeficiency virus seropositive patients

To evaluate the prevalence of adenovirus strains in human immunodeficiency virus (HIV)-positive patients and to investigate their possible role in the onset of diarrhea, a total of 103 stools from HIV-seropositive patients at various stages of infection and 200 stools from sex and age cross-matched control subjects were examined. Adenovirus prevalence was measured by ELISA as well as conventional and rapid cell culture techniques. Results were compared between patients suffering from diarrhea and those without diarrhea. Adenovirus prevalence was statistically greater in HIV-seropositive cases than controls (8.7%, 2.5%, respectively). No significant difference was found between HIV-positive patients with diarrhea and those without gastrointestinal complications (P > 0.05). However, a significant difference in adenovirus prevalence was found between HIV-positive patients with diarrhea and control subjects with diarrhea (P = 0.02). Although viral prevalence varied with the different stages of HIV infection, differences were not statistically significant. In conclusion, although current opinion considers adenoviruses to be no more than opportunistic pathogens, the results of this large-scale study do not exclude a potential reactivation of latent adenovirus in HIV infection and suggest that further effort should be directed to elucidating such a mechanism if it exists as well as investigating the specific role of certain adenovirus serotypes in provoking diarrhea during later stages of HIV infection.

An enzyme immunoassay for the direct detection of adenovirus in clinical specimens

A total of 414 clinical samples were tested by an enzyme immunoassay (EIA) for direct detection of adenovirus as well as cultured in Graham 293, A549, and human diploid foreskin fibroblast cells. Adenovirus was detected in 69 (16.7%) of 414 clinical specimens. The EIA detected adenovirus in 51 (12.3%) of 414 specimens; two were EIA positive only. Adenovirus was isolated from 67 (16.2%) of 414 specimens; 18 were culture positive only. Compared with viral isolation, EIA had a sensitivity of 73.4% and a specificity of 99.4%, with a positive predictive value of 96% and a negative predictive value of 95%.

Physical and chemical methods for enhancing rapid detection of viruses and other agents

Viral replication events can be enhanced by physical, chemical, or heat treatment of cells. The centrifugation of cells can stimulate them to proliferate, reduce their generation times, and activate gene expression. Human endothelial cells can be activated to release cyclo-oxygenase metabolites after rocking for 5 min, and mechanical stress can stimulate endothelial cells to proliferate. Centrifugation of virus-infected cultures can increase cytopathic effects (CPE), enhance the number of infected cells, increase viral yields, and reduce viral detection times and may increase viral isolation rates. The rolling of virus-infected cells also has an effect similar to that of centrifugation. The continuous rolling of virus-infected cultures at < or = 2.0 rpm can enhance enterovirus, rhinovirus, reovirus, rotavirus, paramyxovirus, herpesvirus, and vaccinia virus CPE or yields or both. For some viruses, the continuous rolling of infected cell cultures at 96 rpm (1.9 x g) is superior to rolling at 2.0 rpm for viral replication or CPE production. In addition to centrifugation and rolling, the treatment of cells with chemicals or heat can also enhance viral yields or CPE. For example, the treatment of virus-infected cells with dimethyl sulfoxide can enhance viral transformation, increase plaque numbers and plaque size, increase the number of cells producing antigens, and increase viral yields. The infectivity of fowl plague virus is increased by 80-fold when 4% dimethyl sulfoxide is added to culture medium immediately after infection. The heat shocking of virus-infected cells also has been shown to have a stimulatory effect on the replication events of cytomegalovirus, Epstein-Barr virus, and human immunodeficiency virus. The effects of motion, chemicals, or heat treatments on viral replication are not well understood. These treatments apparently activate cells to make them more permissive to viral infection and viral replication. Perhaps heat shock proteins or stress proteins are a common factor for this enhancement phenomenon. The utility of these treatments alone or in combination with other methods for enhancing viral isolation and replication in a diagnostic setting needs further investigation.

Isolation of seven respiratory viruses in shell vials: a practical and highly sensitive method

The isolation of respiratory viruses in shell vials was compared with isolation in tube cultures in order to determine the sensitivity of the former, rapid method. Twenty of 21 influenza virus and 15 of 15 parainfluenza virus isolates were recovered in shell vials. One hundred twenty-seven of 138 respiratory syncytial virus isolates were detected in shell vials, but only 10 of 21 adenovirus isolates were positive by the rapid method. Shell vials are very effective for the diagnosis of respiratory viral infections, except for those caused by adenovirus.

Evaluation of four methods for rapid detection of adenovirus

Four methods for rapid detection of adenovirus were evaluated by testing retrospectively 28 frozen clinical specimens from which an adenovirus strain had been isolated. After thawing all specimens were retested for the presence of adenovirus by conventional culture on KB cells and found to be positive. The four tests used for rapid detection of adenovirus were a 48-hour culture technique, and an immunoassay, a latex agglutination test and an immunofluorescence assay for direct detection of viral antigen using commercially available reagents. Of the 28 specimens all were positive in the 48-hour culture, 25 (89%) positive in the immunoassay and 10 (36%) positive in the latex agglutination test. Six of eight nasopharyngeal aspirate specimens were positive in the immunofluorescence assay. Twenty-five clinical specimens negative for adenovirus on conventional culture were also negative in the 48-hour culture technique. Overall, the rapid (48-hour) culture technique was 100% sensitive and 100% specific compared to conventional culture. The direct detection of viral antigen by immunoassay was less sensitive, however results were available within a few hours. Prospective comparative studies are warranted to determine whether these rapid techniques could replace conventional culture in the routine diagnosis of adenovirus infection.

Propagation of adenovirus types 40 and 41 in the PLC/PRF/5 primary liver carcinoma cell line

The sensitivity of cell cultures to adenovirus types 40 and 41 (Ad40/41) was compared by means of cell culture infectious dose (ID50) assays using monolayer cultures in microtitre plates. The PLC/PRF/5 cell line derived from a primary human hepatocellular carcinoma was 100 times more sensitive to a laboratory strain of Ad41, and 10 times more sensitive to a laboratory strain of Ad40 and two Ad41 stool isolates, than Graham 293 and Chang conjunctival cells commonly used for the propagation of these viruses. In microtitre plate titration assays PLC/PRF/5 cells retained an optimal condition for longer and displayed cytopathogenic effects earlier and more clearly than the other cell lines. In contrast to previously used cells, PLC/PRF/5 cells also proved successful for the quantitation of Ad41, but not Ad40, by conventional plaque assays. The reason for the exceptional susceptibility of PLC/PRF/5 cells has not been elucidated, but the findings open attractive new doors for research on Ad40/41.