A rapid and simplified micromethod for subtyping varicella-zoster virus

Herpes Simplex Virus Isolates from an Immunocompromised Patient who Failed to Respond to Acyclovir Treatment Express Thymidine Kinase with Altered Substrate Specificity

Ten sequential post-treatment herpes simplex virus type 1 (HSV-1) isolates were obtained from an immunocompromised patient whose infection, during prolonged treatment, became unresponsive to acyclovir (ACV). Of the ten isolates, eight later isolates were resistant in vitro to ACV and ganciclovir (DHPG), but remained sensitive to 9-β-D-arabinofuranosyladenine (ara-A) and phosphonoformate (PFA). Biochemical characterization of plaque-purified clones of the resistant isolates revealed an altered thymidine kinase (TK) substrate specificity phenotype. The comparative nucleotide sequence analysis of polymerase chain reaction (PCR)-amplified DNA encoding the TK genes of one sensitive and two resistant clones showed a single mutation at nucleotide 527. This change would result in a substitution of arginine by glutamine at residue 176 of the polypeptide, a mutation previously observed in a laboratory isolated variant, SC16 Tr7 (Darby et al., 1986).

Preparation of viral DNA from nucleocapsids

Viruses are obligate cellular parasites, and thus the study of their DNA requires isolating viral material away from host cell contaminants and DNA. Several downstream applications require large quantities of pure viral DNA, which is provided by this protocol. These applications include viral genome sequencing, where the removal of host DNA is crucial to optimize data output for viral sequences, and the production of new viral recombinant strains, where co-transfection of purified plasmid and linear viral DNA facilitates recombination.(1,2,3) This procedure utilizes a combination of extractions and density-based centrifugation to isolate purified linear herpesvirus nucleocapsid DNA from infected cells.(4,5) The initial purification steps aim to isolate purified viral capsids, which contain and protect the viral DNA during the extractions and centrifugation steps that remove cellular proteins and DNA. Lysis of nucleocapsids then releases viral DNA, and two final phenol-chloroform steps remove remaining proteins. The final DNA captured from solution is highly concentrated and pure, with an average OD(260/280;) of 1.90. Depending on the quantity of infected cells used, yields of viral DNA range from 150-800 μg or more. The purity of this DNA makes it stable during long-term storage at 4C. This DNA is thus ideally suited for high-throughput sequencing, high fidelity PCR reactions, and transfections. Prior to beginning the protocol, it is important to know the average number of cells per dish (e.g. an average of 8 x 10(6) PK-15 cells in a confluent 15 cm dish), and the titer of the viral stock to be used (e.g. 1 x 10(8) plaque-forming units per ml). These are necessary to calculate the appropriate multiplicity of infection (MOI) for the protocol.(6) For instance, to infect one 15 cm dish of PK-15 cells with the above viral stock, at an MOI of 5, you would use 400 μl of viral stock and dilute it with 3.6 ml of medium (total inoculation volume of 4 ml for one 15 cm plate). Multiple viral DNA preparations can be prepared at the same time. The number of simultaneous preparations is limited only by the number of tubes held by the ultracentrifuge rotor (one per virus; see step 3.9 below). Here we describe the procedure as though being done for one virus.

New variant of varicella-zoster virus

In 1998, a varicella-zoster virus glycoprotein E (gE) mutant virus (VZV-MSP) was isolated from a child with chickenpox. VZV-MSP, representing a second VZV serotype, was considered a rarity. We isolated another VZV-MSP-like virus from an elderly man with herpes zoster. These gE mutant viruses may have arisen through independent mutation or may represent a distinct VZV subpopulation that emerged more than 50 years ago.

Genital recurrent infection occurring 6 months after meningitis due to the same herpes simplex virus type 2 (HSV-2) strain evidence by restriction endonuclease analysis

Herpes simplex virus type 2 (HSV-2) is more often sexually transmitted and associated with genital recurrent infection. However, HSV-2 neurological manifestations such as meningitis were already reported. We describe a case of meningitis due to HSV-2, preceded by signs suggesting a common cystitis, in a woman with no history of primary or recurrent genital infection. Six months later genital herpetic lesions occurred. One HSV-2 strain was obtained from cerebrospinal fluid (CSF) and another from genital lesions. The molecular comparative analysis using restriction endonuclease digestion patterns showed the similarity of the two strains. Our report illustrates that HSV-2 infections are underdiagnosed and that molecular techniques can be of value in clarifying the physiopathology of HSV diseases.