Changes in the cell surface properties of Treponema pallidum that occur during in vitro incubation of freshly extracted organisms.

We previously reported that a number of Treponema pallidum membrane proteins appear to reside on the cell surface, since intact treponemes radiolabeled by overnight incubation in medium containing [35S]methionine bind immunoglobulin G (IgG) antibodies directed against these proteins. In the present study, it was found that freshly extracted organisms radiolabeled in vitro for only 2 h inefficiently bound IgG antibodies directed against just two proteins of molecular weights 40,000 and 34,000. An in vitro incubation period of greater than 8 h was required before IgG antibodies present in rabbit syphilitic serum could recognize additional protein antigens on the cell surface. Treatment of aged treponemes, but not freshly extracted organisms, with 0.04% sodium dodecyl sulfate selectively removed a membranous layer from the treponemal surface. Only three treponemal proteins were found associated with this structure, including the same 40,000- and 34,000-molecular-weight proteins mentioned above. These two proteins most likely represent endoflagellar subunits, since they were precipitated with rabbit antisera prepared against purified endoflagellar subunits of the cultivable treponemal strain Treponema phagedenis. Further evidence also was obtained that cells of T. pallidum actively secrete into their extracellular environment a unique class of low-molecular-weight proteins

Evaluation of the Gen-Probe Aptima HIV-1 RNA Qualitative Assay as an Alternative to Western Blot Analysis for Confirmation of HIV Infection▿

The Gen-Probe Aptima HIV-1 RNA qualitative assay was evaluated as an alternative to Western blot analysis for the confirmation of HIV infection using serum samples that were repeatedly reactive for HIV antibodies. The Aptima HIV assay readily discriminated between HIV-1-infected and -uninfected individuals and effectively reduced the number of indeterminate results relative to Western blot analysis

Decline in Cases of Rotavirus Gastroenteritis Presenting to The Children's Hospital of Philadelphia after Introduction of a Pentavalent Rotavirus Vaccine▿

A pentavalent rotavirus vaccine for infants became available in the United States in February 2006. By 2007, vaccination rates nationwide were estimated to be ∼50%. We studied the effectiveness of the vaccine in a real-world setting outside of a clinical trial. All children presenting to The Children's Hospital of Philadelphia with acute gastroenteritis have been monitored for the presence of rotavirus antigen in the stool by enzyme-linked immunosorbent assay (ELISA [followed by genotyping if ELISA positive]) since the 1994-1995 epidemic season, presenting a unique opportunity to assess the impact of the recently introduced vaccine. The annual number of community-acquired cases over the preceding 13 years had approached or exceeded 100, with 271 cases in 2005 to 2006 and 167 cases in 2006 to 2007. In the 2007-2008 season, only 36 community-acquired cases were identified, representing an 87% reduction from the same period in 2005 to 2006. G3 was the predominant serotype, accounting for 15 community cases (42%). Our study is limited by its observational design using historical comparisons. Nonetheless, the abrupt decline in rotavirus gastroenteritis cases during the 2007-2008 season likely resulted from vaccination. Because protection rates appeared to have exceeded vaccination rates, herd immunity may have contributed to some degree to the effectiveness of the vaccine

Detection of Echovirus 18 in Human Breast Milk▿

We detected enteroviral RNA and cultured infectious virus from a series of banked breast milk samples from the mother of an infant with neonatal sepsis; sequencing of the enterovirus isolate identified it as echovirus type 18. In this case, it is possible that enterovirus transmission occurred through the breast milk

Biochemical Characterization a virus isolate from a patient with Herpes Keratitis clinically-resitant to Acyclovir

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Comparison of Methods for Identifying Resistant Herpes Simplex Virus and Measuring Antiviral Susceptibility

Background: A number of in vitro assays are used to determine susceptibility of HSV to antiviral agents, but results from these in vitro assays do not necessarily correlate with treatment outcome. Objectives: A method with improved capability for identifying an isolate as acyclovir (ACV) or penciclovir (PCV) resistant when resistance is borderline could greatly improve the management of HSV disease. Study design: A comparative evaluation of four in vitro assays, plaque reduction (PRA), DNA hybridization, plating efficiency (PEA) and plaque autoradiography (PAR) was performed to accurately identify and measure resistance of a TK-altered clinical HSV isolate (HSV-1 N4) from a patient who was non-responsive to ACV treatment. Two established criteria for the prediction of antiviral resistance, IC 50≥2.0 μg/ml or an IC 50 greater than 10× above a sensitive virus IC 50, as well as testing in human (MRC-5) and nonhuman (Vero and CV-1 monkey kidney) cell lines were evaluated. Results: The PRA and DNA hybridization assays accurately identified HSV-1 N4 as ACV r in human cells when using the 10× above sensitive virus IC 50 resistance criterion. Moreover, the PEA and PAR assays failed to classify HSV-1 N4 as drug resistant and indicate that these technologies alone are inadequate for identifying resistant virus. Conclusions: The data presented herein indicate that the PRA and DNA hybridization assays most accurately identified an otherwise borderline-resistant isolate as drug resistant: (i) when a sensitive virus is used within each individual assay as a control, (ii) when ACV and PCV susceptibility is evaluated in human cells, and (iii) when the 10× above sensitive IC 50 criterion is used to classify a virus as drug-resistant. Testing of additional clinical samples is warranted to further confirm these findings. © 2002 Elsevier Science B.V. All rights reserved.SCOPUS: ar.jinfo:eu-repo/semantics/publishe