Point: is the era of viral culture over in the clinical microbiology laboratory?

Conventional tube culture systems have long been the mainstay in clinical virology for the growth and identification of viruses from clinical specimens. Innovations such as centrifugation-enhanced shell vial and multiwell plate cultures and the use of genetically engineered and mixed cell lines, coupled with faster detection of viral replication, have allowed for reasonable turnaround times for even some of the most slowly growing clinically important human viruses. However, molecular methods, in particular, the PCR, have usurped the role of viral culture in many laboratories, limiting the use of this traditional method of virus detection or replacing it altogether. Advances and improvements in molecular technology over time have also resulted in newer generations of more rapid and accurate molecular assays for the detection, quantification, and genetic characterization of viruses. For this point-counterpoint, we have asked two individuals, Richard L. Hodinka of the Children's Hospital of Philadelphia, a clinical virologist whose laboratory has completely eliminated viral culture in favor of molecular methods, and Laurent Kaiser, head of the Virology Laboratory at the University of Geneva Hospital, who continues to be a strong advocate of viral culture, to discuss the relevance of viral culture in the molecular age.

Phage choice, isolation, and preparation for phage therapy.

Phage therapy is the use of bacteriophages--viruses that use bacteria as their host cells--as biocontrol agents of bacteria. Currently, phage therapy is garnering renewed interest as bacterial resistance to antibiotics becomes widespread. Historically, phage therapy was largely abandoned in the West in the 1940s due to the advent of chemical antibiotics, and the unreliability of phage-based treatments when compared to antibiotics. The choice of phage strain and the methods of phage preparation are now thought to have been critical to the success or failure of phage therapy trials. Insufficiently virulent phages, especially against actual target bacteria, allow bacteria to survive treatment while poorly prepared phage stocks, even if of sufficiently virulent phages, lack the numbers of viable phages required for adequate treatment. In this review we discuss the factors that determine the methods of isolation, analysis, and identification of phage species for phage therapy. We go on to discuss the various methods available for purifying phages as well as considerations of the degree of purification which is sufficient for various applications. Lastly, we review the current practices used to prepare commercial phage therapy products.

[Evolution of isolation and identification techniques of waterborne viruses]. / Evolution des techniques d'isolement et d'identification des virus des eaux.

The paralytic potential of the poliovirus was recognized as early as the 14th century B.C. as illustrated in Egyptian art. But it is only after the four last decades that methods for their concentration from water and their identification were performed. Among several of them the adsorption-elution method was retained. Nevertheless two important barriers had to be ran-over. The first one was the concentration-elution steps on different materials which had to be improved. The second one was the typing method which had to move from particle by particle identification to entire viral population. Despite of these advances only a few cytopathogenic serotypes were found. The reverse transcriptase-polymerase chain reaction with its far more wide spectrum allows the fast and direct identification of viral nucleic acids (or their fragments) of almost all viruses, cytopathogenic or not. With this method elevated amounts of drinking water samples were found positive for several non cytopathogenic viruses. The sanitary significance of these results has still to be proved.