Operator-induced
biological contamination in cell cultures is a multifaceted problem involving the unexpected introduction of other animal cells, microbial and viral contaminants. Detailed studies on animal cell cross contaminations have been performed and published. The frequency of detection of problem cultures has been as high as 36% for one service performed in the USA, with interspecific cross contamination accounting for 25% and human intraspecific contamination representing 11%. Awareness of the potential of this problem plus the application of several characterizations are key factors for its control. For example, fluorescent antibody staining,
isoenzyme analyses, cytogenetic evaluations and DNA fingerprinting using
molecular probes are needed for quality assurance on master seed stocks. Detection of microbial contamination is relatively straightforward, but the prevalence of mycoplasmal
infections in cell cultures used in general research is still a significant problem. Detection services report frequencies of
infection varying from 10% upwards, depending upon the country and laboratory of origin. The utilization of prescreened
reagents and
antibiotic-free cultivation, plus the application of improved procedures, such as
fluorescent dyes and
molecular probes for detection, provide effective means of avoiding
mycoplasma infection and facilitating control. For many viruses, the presence of mycoplasma reduces immunoreactivity, suppresses
transcriptase and other
enzyme activities, reverses viral neutralization etc. The introduction of viral contaminants into cell cultures is perhaps the most problematic, especially where no cytopathic effect is produced. Few cases are documented where technicians infected with specific viruses have introduced these unwittingly into cultures in their care. The potential exists, however, as reports have appeared documenting the considerable stability of rhinoviruses, respiratory syncytial virus, rotaviruses and others, in
aerosols on workers' hands and safety hood surfaces. The
infection of cell cultures via other contaminated cells or
reagents such as sera is a related problem. In this regard, the
infection of transplantable tumor cell lines with lymphocytic choriomeningitis virus from host animals led to an outbreak of the disease in medical center personnel. Similar
infection of rat cell lines exposed to animals harboring hantaviruses has been reported. Technical staff in US government laboratories have been infected with human immunodeficiency virus produced in cultured cells. Such serious public health hazards warrant repeated emphasis. The use of multiple cell lines in a given laboratory, including cultures known to be virally infected, compounds the problems and necessitates application of preventive methods both to avoid
cross-infections and to document freedom from contamination.(ABSTRACT TRUNCATED AT 250 WORDS)