Evaluation of three types of cell culture for recovery of adenovirus from clinical specimens

Adenovirus

Adenoviruses are a highly prevalent infection that can cause a range of clinical syndromes in immunocompromised patients, ranging from localized disease of the respiratory tract, gastrointestinal tract, or urinary tract to disseminated disease. Adenovirus infections may develop in this unique population as the result of primary infection or reactivation of latent virus. Disease can be potentially progressive with high rates of mortality in patients with pneumonia and disseminated disease. Fortunately, cidofovir and its lipid ester, brincidofovir, appear to be effective for the treatment of adenovirus, although neither is specifically approved for this indication. Adenovirus should always be considered when immunocompromised patients present with any clinical syndrome that could be compatible with adenoviral infection. Once disease is suspected, cultures or molecular testing of appropriate specimens should be obtained and blood should be sent for adenovirus polymerase chain reaction (PCR) whenever adenovirus is suspected. Monitoring of quantitative viral loads in blood is helpful in predicting response to therapy with a significant drop (>1 log) associated with a higher probability of clinical response.

Rapid and sensitive diagnosis of human adenovirus infections by a generic polymerase chain reaction

A new adenovirus specific nested polymerase chain reaction (PCR) method is described. It was designed inside the hexon protein gene of the adenovirus genome, and was able to detect DNA of all 47 human adenovirus types in a wide range of clinical samples. A sensitive internal control system able to assure proper analytical conditions for the amplification of as few as 100 molecules of a heterologous DNA was included to avoid false negative results. Sensitivity was estimated at about 10 molecules per tube of a plasmid containing an insert of the first amplification product. The method was able to detect adenovirus infection in 31/43 conjunctival scrapings from patients with acute kerato conjunctivitis 10/40 nasopharyngeal aspirates from patients admitted to hospital with acute respiratory disease and 2/26 urine samples from patients with haemorrhagic cystitis with better sensitivity than cell culture or rapid diagnosis by antigen detection by immunofluorescence (IF) in the case of respiratory specimens. Only two of 17 stools positive for a group F adenovirus specific latex immunoassay were PCR negative. The internal control system avoided a false negative result on another two stool samples. In conclusion, the method described below was shown to be useful for rapid diagnosis of adenovirus infections with higher sensitivity than antigen detection by IF.

Adenovirus infections in hematopoietic stem cell transplant recipients

We report a 12% incidence of adenovirus infections among 532 recipients of hematopoietic stem cell transplant (HSCT) from January 1986 through March 1997. The median time from day of stem cell infusion to first positive culture was 41 days. Recipients of allogeneic stem cells, as opposed to autologous stem cell recipients, were more likely to have a culture positive for adenovirus (16% vs. 3%; P<.0001). Pediatric patients were also more likely than adults to have a positive culture (23% vs. 9%; P<.0001). Among stem cell recipients with partially matched related donors, pediatric recipients appear to be at significantly greater risk for infection than adult recipients (P<.001). Positive cultures were associated with evidence of invasion in 64% of cases (41 of 64). A multiple logistic regression analysis showed that isolating adenovirus from more than 1 site correlated with greater risk for invasive infections (P=.002). Invasive infections were associated with poorer chance of survival.

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%.

Evaluation of immunofluorescent reagents, centrifugation, and conventional cultures for the diagnosis of adenovirus infection

In this study we have evaluated four fluorescent antibody reagents, three monoclonal and one polyclonal, for identification of adenovirus isolates and compared four conventional cultures (human embryonic kidney, A549, HEp-2, and MRC-5 cells) with centrifugation culture for rapid diagnosis. For identification of adenovirus isolates by immunofluorescence, CDC reagent and Adenoclone, both monoclonal antibodies to the hexon group-reactive antigen, were more sensitive and easier to interpret than the other two reagents tested. HEK and A549 cells were the most sensitive for isolation of adenovirus. Although A549 cells were an inexpensive alternative to HEK, A549 cell monolayers deteriorated more rapidly and passages were more often required. Centrifugation cultures with A549 cells detected 77% of positives within 2 days and 100% within 5 days, whereas isolation in conventional culture required up to 10 days for HEK and up to 20 days for MRC-5 cells.

The impact of cell culture sensitivity on rapid viral diagnosis: a historical perspective

The contribution of cell culture systems in the diagnosis of viral infections has been well recognized over the years. Not only did such systems make possible the direct isolation and identification of viruses, but also the production of viral diagnostic reagents for rapid diagnosis, the evaluation of antiviral agents, and the production of vaccines for the control of viral diseases. Although many reagents for rapid detection of viral antigens/genomes are currently available, none will make possible discoveries of new viral agents. Thus sensitive cell culture systems are still essential for the rapid and accurate diagnosis of viral infections. Since, as yet, no single cell culture system is susceptible to all viruses, the constant search for additional sensitive cell culture systems for detecting those unknown and/or currently non-cultivable viral agents continues to be an open area of investigation in the field of diagnostic virology.

Use of A-549 cells in a clinical virology laboratory

A-549 cells were compared with other cell lines for virus recovery, except from specimens submitted specifically for detection of cytomegalovirus. Of 589 specimens submitted specifically for detection of herpes simplex virus (HSV), 163 (28%) were positive for HSV--159 (97.5%) in A-549 cells and 156 (96%) in primary rabbit kidney cells. HSV cytopathic effect was identified an average of 0.6 day earlier in A-549 cells. Virus was recovered from 194 (11%) of 1,790 specimens submitted for general virus isolation. Of 40 HSV isolates, 85% were positive in A-549 cells, 72.5% were positive in MRC-5/WI-38 cells, and 42.5% were positive in HEp-2 cells. With adenovirus, 96% of 45 isolates were detected in A-549 cells, 62% were detected in HEp-2 cells, 38% were detected in MRC-5/WI-38 cells, and 31% were detected in PMK cells. Of the 76 enterovirus-positive specimens, 71% were positive in PMK cells, 62% were positive in A-549 cells, and 62% were positive in MRC-5/WI-38 cells. None of 12 respiratory syncytial virus, 14 rhinovirus, or 7 influenza A virus isolates were detected in A-549 cells. Of the cell lines examined, A-549 cells performed optimally for recovery of HSV and adenovirus, they allowed good growth of many of the enterovirus isolates, but they did not allow recovery of any of the respiratory syncytial virus, rhinovirus, or influenza A virus isolates.