Yung T. Huang

Evidence of human bocavirus circulating in children and adults, Cleveland, Ohio

Abstract Background Viral respiratory illness is a major cause of morbidity and mortality. The human bocavirus (HBoV) is a recently recognized parvovirus isolated from human respiratory secretions. Objectives To define the clinical and epidemiologic characteristics in adult and pediatric patients with evidence of HBoV. Study design From October 2005 through October 2006, we screened respiratory samples from children and adults negative for common respiratory pathogens for HBoV by PCR. Demographic and clinical characteristics were obtained from medical records of HBoV positive individuals. Results Of 2075 samples screened, 1826 (88.0%) represented distinct respiratory events: 1539 (84.3%) were pediatric (<18 years), and 273 (15.0%) adult (≥18 years). Forty (2.2%) patients had HBoV: 36 (2.3%) children and 4 (1.5%) adults. HBoV positive children had history of prematurity (31.3%) and cardiac disease (18.8%). Adults had underlying pulmonary (100%) and cardiac (50%) disease. Twenty-seven children (84.4%) were hospitalized; 9 (28.1%) required intensive care. All adults were hospitalized; none required intensive care. Nosocomial acquisition likely occurred in 3 patients. Conclusions HBoV circulates in Cleveland, OH, in children and adults with similar frequencies, and can warrant hospitalization and intensive care. Further study would clarify our understanding of this newly recognized human pathogen.

Human coronaviruses are uncommon in patients with gastrointestinal illness

Abstract Background Coronaviruses infect numerous animal species causing a variety of illnesses including respiratory, neurologic and enteric disease. Human coronaviruses (HCoV) are mainly associated with respiratory tract disease but have been implicated in enteric disease. Objectives To investigate the frequency of coronaviruses in stool samples from children and adults with gastrointestinal illness by RT-PCR. Study design Clinical samples submitted for infectious diarrhea testing were collected from December 2007 through March 2008. RNA extraction and RT-PCR was performed for stools negative for Clostridium difficile using primer sets against HCoV-229E, HCoV-OC43, HCoV-NL63, and HCoV-HKU1. Clinical data from samples positive for coronaviruses were reviewed and recorded. Results Samples from 479 patients were collected including 151 pediatric (≤18 years), and 328 adults (>18 years). Of these samples, 4 patients (1.3%, 2 adult; 2 pediatric) screened positive for the presence of a coronavirus. All detected coronaviruses were identified as HCoV-HKU1. No stools screened positive for either HCoV-229E, HCoV-NL63 or HCoV-OC43. All HCoV-HKU1 positive samples occurred between mid-January to mid-February. Clinical manifestations from HCoV-HKU1 positive patients included diarrhea, emesis and respiratory complaints. Three (75%) patients were admitted to the hospital with a median length of stay of 6 days. Conclusions Coronaviruses as a group are not commonly identified in stool samples of patients presenting with gastrointestinal illness. HCoV-HKU1 can be identified in stool samples from children and adults with gastrointestinal disease, with most individuals having respiratory findings as well. No stool samples screened positive for HCoV-NL63, HCoV-229E, or HCoV-OC43.

Engineered BGMK Cells for Sensitive and Rapid Detection of Enteroviruses

ABSTRACT Decay-accelerating factor (DAF) has been reported to be a cellular receptor for several enteroviruses. Buffalo green monkey kidney (BGMK) cells expressing human DAF (BGMK-hDAF cells) showed increased susceptibility and sensitivity to several types of enteroviruses compared to wild-type BGMK cells. When 17 frozen positive clinical samples were tested, BGMK cells detected 8 and BGMK-hDAF cells detected 16. Since the CaCo-2 cell line has been documented to support the replication of most enteroviruses, CaCo-2 cells were mixed with BGMK-hDAF cells in order to increase the number of viruses detected. Thirty-four frozen clinical samples that previously had tested positive for enteroviruses were tested, and the following numbers were detected: 33 of 34 by CaCo-2/BGMK-hDAF cells, 29 of 34 by CaCo-2/BGMK cells, 28 of 34 by H292/RD (E-mix A) and A-549/BGMK (E-mix B) cells, and 26 of 34 by MRC-5 and pRhMK cells.

Cryopreserved cell monolayers for rapid detection of herpes simplex virus and influenza virus

ABSTRACT Cryopreserved cell monolayers are a new cell culture technology intended to ensure the availability of cells in the laboratory for virus detection. Two cryopreserved cell monolayers, ELVIS for the detection of herpes simplex virus (HSV) and R-Mix for the detection of influenza virus, were evaluated. The results indicated that fresh and cryopreserved cell monolayers are comparable in sensitivity for the detection of HSV and influenza virus. The cells retain the same level of sensitivity for up to 4 months at −80°C.

HSV IgG antibody inhibits virus detection in CSF

BACKGROUND Before PCR testing of cerebrospinal fluid (CSF), laboratory diagnosis of herpes encephalitis (HSE) was based on virus isolation from brain biopsy. Viral isolation from CSF has limited clinical value due to low virus recovery; the cause for which has not been demonstrated. OBJECTIVE To investigate the role of anti-HSV antibodies on recovery of HSV from CSF via cell culture. STUDY DESIGN HSV-positive CSF samples were evaluated for their ability to neutralize HSV in cell culture. The presence of HSV-specific IgG and IgM antibodies were analyzed using HSV-infected cells. To identify whether HSV-specific IgG is the cause of viral inhibition, IgG was removed using anti-human IgG magnetic beads. Viral inhibition from CSF originating from asymptomatic patients was examined as a comparison. RESULTS CSF from 13 patients with acute HSV CNS disease was analyzed. All displayed high levels of viral neutralization to both HSV-1 and HSV-2 regardless of the infecting subtype. Interestingly, all the CSF samples stained strongly for anti-IgG antibody but none for anti-IgM antibody. Removal of IgG from CSF eliminated the viral inhibitory activity. Neutralizing IgG antibody was also found to be common in CSF of most patients, even in the absence of HSV disease. CONCLUSIONS Viral specific IgG is the major determinant of viral inhibition in CSF and prevents virus recovery in cell culture. In CSF from HSE un-infected patients, viral inhibitory IgG originates from circulating serum antibody and is commonly present in CSF. However, this inhibitory IgG is not protective for the development of HSV disease.

Calu-3/A-549 mixed cells as a replacement for primary rhesus monkey kidney cells for virus detection

BACKGROUND Primary kidney cells derived from rhesus macaques (pRhMK) are heavily relied upon for the detection and culture of a wide range of clinically relevant viruses. The use of these cultures is problematic due to the possible presence of endogenous viruses, the need to sacrifice a primate, and the inherent variance found in primary cultures. OBJECTIVE To develop a continuous cell line or mixed cell co-culture that could replace dependence on pRhMK cells. STUDY DESIGN Cells from the Calu-3 and A-549 cell lines were used to prepare mixed cell monolayers that were compared to pRhMK cells for their ability to detect respiratory viruses, measles, mumps, enteroviruses, and herpes viruses. Clinically derived and laboratory virus strains were used for these comparisons in culture plates or 16 mm tubes. RESULTS Calu-3/A-549 cells are more sensitive than pRhMK for the detection of adenovirus, enteroviruses and herpes simplex virus and are about equally sensitive for the detection of other respiratory viruses, measles, mumps and varicella-zoster virus. CONCLUSIONS Calu-3/A-549 cells are an equivalent or better alternative to pRhMK cells for the detection of many clinically relevant viruses.