Efforts toward a More Useful Viral Diagnostic Laboratory ERNEST

C.

HERRMANN, JR.,

l'n.D.

Mayo Clinic and Mayo Foundation, Department of Microbiology Rochester, Minnesota 55901

and

Immunology,

ABSTRACT

T H E TRADITIONAL METHODS for diagnosis of

viral infections usually involve isolation of a virus, when possible, definitive serologic typing of the isolated virus, and measurement of antibody levels in acute and convalescent sera, specific for the viral isolate, prior to reporting the information to the physician. 2 ' 8 Such procedures make substantial demands on the physician to collect specimens for the diagnosis of diseases that generally are mild and self-limiting, and the results of such an effort may not be reported to him for weeks or even months. The fact that these practices have little to do with the needs of the patient has been discussed in detail in a recent publication. 8 In the past, viral diagnostic laboratories have not imitated the approacli used in Received January 18, 11)71; accepted for publication February 2, 1971. Dr. Herrmann's present address is Peoria School of Medicine, 405 First National Bank Building, Peoria, 111. 61602. Requests for reprints should be sent to the Section of Publications, Mayo Clinic, Rochester, Minnesota 55901. 681

bacteriology, in which a potential pathogen is reported to the physician at the time of isolation, without confirmatory serologic tests. As discussed in previous reports, 4 - 8 the reason for this traditional distinction between the approach of the bacteriologist and the approach of the virologist is that the virology laboratories are pursuing epidemiologic studies rather than performing a diagnostic service related to medical practice. The following presentation will summarize a 9-year attempt to follow the general approach used in bacteriologic diagnosis—reporting virus isolations when first observed, along with some indication of the general class of virus isolated. The results reported here, for more than 4,000 virus isolations, can be considered the minimal efficiency that might be expected from a viral diagnostic laboratory. Materials and Methods The virus isolations reported here were obtained by culturing more than 30,000 specimens received as part of the routine

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Herrmann, Ernest C , Jr.: Efforts toward a more useful viral diagnostic laboratory. Amer. J. Clin. Path. 56: 681-686, 1971. More than 4,000 viruses were isolated in a 9-year period and reported to the physician virtually as soon as virus activity was detected in cell cultures or mice. Within 4 days of receipt of specimens, 44.3% of viral isolates had been reported to the physician and within 7 days, 72.8% had been reported. These preliminary reports also correctly indicated the general type of virus isolated 90.4% of the time. Only in 4.7% of the virus isolations was the type of virus incorrectly indicated, and in 4.9% of the isolations, only "virus" was reported.

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HERRMANN, JR.

A.J.C.P.—Vol.

56

the early years when lack of experience may have caused some delays in reporting a viral isolate. It also seems reasonable to assume that, if cell cultures had been ob-

Of the influenza virus isolates, most were the Hong Kong variant of the A2 type or the 1968 to 1970 variant of the B type, both of which produced extensive CPE

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practice of medicine. Details of the sources served daily rather than three times per and types of specimens, the patient popu- week, many viral isolates would have been lation from which they were obtained, reported to the physician sooner. and their handling and preparation for Many serotypes of coxsackieviruses of the virus isolation procedures have been de- A group (cox. A) produce little or no CPE scribed. 3-5 ' 10 in cell cultures but must be detected by Virus isolations were made in HeLa, WI- their ability to paralyze infant mice after 38 human fibroblast, and rhesus monkey injection by the intraperitoneal route. It kidney (MK) cell cultures, as well as in would have been very costly to inject all infant mice. The source, preparation, and specimens into mice, so the results prehandling of these cultures have been de- sented here are only for specimens carefully scribed in previous publications. 4 ' 5 >" De- selected for the possibility that cox. A viscriptions of both the presumptive and the ruses might be present. All patients with definitive identification of virus isolates oral lesions, as occurs with herpangina, and also have been published.3- *• °> ~'< °>10 Thethose with central nervous system diseases sources of all chemical and biologic re- were believed to be likely sources of these agents and cell culture media will be found viruses. Furthermore, the attempts to detect these viruses were limited to the sumin the references cited. mer and fall months, a period when they Results and Discussion are much more prevalent. Even with this Cell cultures were observed thrice weekly limited program, using at least 18 litters of to detect virus-induced cytopathic effects infant mice per week, there were signifi(CPE). Hemadsorption (HAd) tests were cant delays before specimens could be inperformed on MK cell cultures every fifth jected into mice. For this reason the data day of the incubation during periods of in Table 1 indicate that fewer than 50% high prevalence of hemadsorbing viruses, of cox. A viruses were reported to the phybut only on the tenth day of incubation sician by the tenth day after receipt of during low prevalence. Infant mice were the specimens. If all the specimens had observed 6 days per week. It was possible, been injected into mice the day they were with this minimal effort, to detect and re- received, the average detection of virus acport more than 70% of viral isolates to tivity4 would have occurred within 4 to 5 the physician within a week after receipt of days. In a further attempt to solve this the specimens (Table 1). Almost half of the problem, large litters of mice were subisolates were reported 4 days after receipt divided into groups of five and given to of the specimens. This was largely due to foster mothers whose own litters had the frequent isolation of herpes simplex reached 3 weeks of age. The acceptance of virus (HSV), a virus that rapidly produces the new infant mice by the foster mothers CPE in WI-38 cell cultures. It was possible was very high, but again, it did not resolve to report to the physician more than 30% the overall problem. T o make an already of the isolations of HSV and coxsackie- costly program more economical, no atviruses of the B type within 48 hr. after tempt was made to serotype most cox. A the specimens were received. Of course, isolates. Coxsackieviruses types A9 and A16 these percentages are based on the entire produce CPE in cell cultures and can be experience for a 9-year period, including serotyped more economically.

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