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C B Stephensen

Publications and source records attributed to C B Stephensen.

At least 37 records · Page 2Linked to original sources
PubMed1997

Detection of enterotropic mouse hepatitis virus fecal excretion by polymerase chain reaction.

A reverse transcription and polymerase chain reaction method was developed and used to detect fecal excretion of enterotropic mouse hepatitis virus (MHV). A nested set of primers for polymerase chain reaction was located in the polymerase region of the MHV genome. The assay was used to follow the time course of enterotropic MHV excretion in mice after oronasal inoculation with the virus. The assay detected MHV genome excretion in all mice beginning on day 3 through day 21 after inoculation. No MHV genome was detected in inoculated mice on or after day 27 following inoculation. This time course of detection of excreted virus corresponded to the period of infectivity of this isolate in a previous study. These results indicate that reverse transcription and polymerase chain reaction are useful for enterotropic MHV detection in specimens that are easily and noninvasively obtained and are clinically relevant.

Animals↗
PubMed1996

Vitamin A deficiency diminishes the salivary immunoglobulin A response and enhances the serum immunoglobulin G response to influenza A virus infection in BALB/c mice.

We examined the effect of vitamin A deficiency on the secretory immunoglobulin (Ig) A and serum IgG response to influenza A virus infections in BALB/c mice. Mice fed a vitamin A-deficient (VAD mice) or a control diet were inoculated with influenza virus at 7 or 9 wk of age when serum retinol concentration had dropped to < or = 0.35 mumol/L in the VAD mice. The influenza-specific salivary IgA response to a mild infection (intranasal inoculation without anesthesia) was not significantly lower in the VAD group (5.3 +/- 2.1% of total IgA 4 wk after infection) than in the control group (10 +/- 11%, P > 0.05). In a separate experiment, this salivary IgA response was significantly lower in the VAD mice (0.3 +/- 0.4% of total IgA) following a more severe infection (intranasal infection while under anesthesia) than it was in control mice (4.2 +/- 4.6% of total IgA, P < 0.0001). In contrast, the concentration of total salivary IgA was uniformly greater in the VAD mice than in the control mice during both the mild infection (VAD, 17 +/- 6 mg/L vs. control, 8 +/- 11 mg/L at 3 wk, P < 0.0001) and the severe infection (VAD, 38 +/- 30 mg/L vs. control, 9 +/- 7 mg/L, P < 0.0001). Similarly, the influenza-specific serum IgG response was also greater in the VAD mice than in the control mice during both the mild infection (VAD, 194 +/- 91 mg/L vs. control, 79 +/- 95 mg/L at 5 wk, P = 0.0002) and the severe infection [VAD median, 202 mg/L (25th, 75th percentiles, 153, 409 mg/L) vs. control, 123 mg/L (42, 165 mg/L), P = 0.0023]. Thus VAD significantly impairs the secretory IgA response to influenza infection but modestly increases the serum IgG response to the same infection.

Animals↗
PubMed1996

Vitamin A deficiency has different effects on immunoglobulin A production and transport during influenza A infection in BALB/c mice.

We examined the effect of advanced vitamin A deficiency (serum retinol < or = 0.35 micromol/L, with weight gain significantly lower than in controls with free access to food) on the secretory immunoglobulin A (IgA) response to a mild, upper respiratory tract infection with influenza A virus in BALB/c mice. Mice fed a vitamin A-deficient or control diet were infected intranasally at 11 to 12 wk of age. The influenza-specific salivary IgA response was lower in the vitamin A-deficient mice (0.11 +/- 0.13% of total IgA 4 wk after infection) than in controls with free access to food (2.73 +/- 1.86%, P < 0.0001). In a separate experiment, the response of vitamin A-deficient mice (0.42 +/- 1.51%) was also lower than that of pair-fed controls (3.43 +/- 4.76%, P < 0.0001). In addition, fewer influenza A-specific IgA-secreting plasma cells were found in the salivary glands of vitamin A-deficient mice (geometric mean 3.0%) than in controls with free access to food or in pair-fed controls (geometric mean 8.7%, P < 0.0001). Although the pathogen-specific IgA response was decreased, vitamin A-deficient mice had a significantly higher concentration of total salivary IgA (31.9 +/- 15.9 mg/L) than did the pair-fed controls (14.3 +/- 8.4 mg/L, P < 0.0001). Northern blot analysis of salivary gland RNA revealed that these vitamin A-deficient mice also had greater levels of mRNA of the polymeric immunoglobulin receptor (pIgR), which transports IgA across mucosal surfaces (plgR: beta-actin mRNA ratio = 7.8 +/- 0.8), than did pair-fed control mice (3.7 +/- 0.4, P = 0.0001). These data demonstrate that vitamin A deficiency has contrasting effects on the secretory IgA response to influenza infection, with a principal effect being a decrease in the pathogen-specific response.

Animals↗
PubMed1996

Vitamin A and retinoids in antiviral responses.

Vitamin A deficiency results in multiple derangements that impair the response to infection. This review focuses on experimental models of specific virus infections and on cytokines and cells with cytolytic activity important to antiviral defenses. Altered specific antibody responses and greater epithelial damage in vitamin A-deficient hosts are consistent findings. The cytolytic activity of natural killer cells and various cytokine responses are altered. The inflammatory response to infection may also result in derangements in the transport and metabolism of retinol. We speculate that interaction of several factors may combine to explain the greater severity of infection seen in vitamin A-deficient animals and children. In addition to a preexisting lack of tissue vitamin A, these factors may include reduced mobilization and increased excretion of retinol during the acute phase response to infection, poor innate and specific immune response to virus, and delayed repair of damaged epithelia. Foci of vitamin A-deficient epithelia may be sites of penetration of bacteria and other agents, leading to secondary infections and contributing to an increased severity of infections and poor outcome in vitamin A-deficient animals and humans.

Animals↗
PubMed1995

Urinary excretion of retinol in children with acute diarrhea.

Acute infections of childhood are associated with an increased of xerophthalmia, apparently due to depletion of vitamin A stores. The mechanism responsible for this is not known. Recently, it has been reported that severe infections in adult patients (ie, sepsis and pneumonia) result in excretion of large quantities of retinol in the urine. In 44 children hospitalized for treatment of acute diarrhea we found mean urinary excretions of 1.44 mumol retinol/24 h on day 1 of hospitalization, 0.62 mumol retinol/24 h on day 2, and 0.23 mumol/24 h on day 3. Healthy control subjects matched for age did not excrete measurable amounts of retinol in the urine. Retinol excretion was associated strongly with rotavirus diarrhea and presence of fever. Furthermore, serum retinol concentration was negatively associated with duration of diarrhea before hospitalization, suggesting that urinary excretion of retinol may be an important contributor to vitamin A depletion.

Acute Disease↗
PubMed1995

cDNA sequence analysis confirms that the etiologic agent of callitrichid hepatitis is lymphocytic choriomeningitis virus.

Callitrichid hepatitis is an infection of New World primates caused by an arenavirus, currently referred to as callitrichid hepatitis virus, that is closely related to lymphocytic choriomeningitis virus (LCMV). We have cloned and sequenced the GP-C gene of callitrichid hepatitis virus and found that the cDNA sequence is 84 to 86% identical to those of the GP-C genes of LCMV strains Armstrong and WE, while the deduced amino acid sequence is 95 to 96% identical to those of the GP-C gene products of the same strains. This high degree of similarity indicates that the etiologic agent of callitrichid hepatitis is in fact LCMV. The wide geographic distribution of callitrichid hepatitis outbreaks in the United States serves as a reminder that LCMV is also a human pathogen whose public health implications are not well understood.

Amino Acid Sequence↗
PubMed1994

Vitamin A is excreted in the urine during acute infection.

Episodes of acute infection are thought to deplete body stores of vitamin A. The mechanism by which this might occur is not known, but increased metabolic requirements are presumed to play a role. We have found, however, that significant amounts of retinol and retinol-binding protein (RBP) were excreted in the urine during serious infections, whereas only trace amounts were found in the urine of healthy control subjects. The geometric mean excretion rate in 29 subjects with pneumonia and sepsis was 0.78 mumol retinol/d. Subjects with fever (temperature > or = 38.3 degrees C) excreted significantly more retinol (geometric mean = 1.67 mumol/d) than did those without fever (0.18 mumol/d; t = 3.53, P < 0.0015). Aminoglycoside administration and low glomerular filtration rates (< 35 mL/min) were also associated with higher rates of urinary retinol excretion. Thirty-four percent of patients excreted > 1.75 mumol retinol/d, equivalent to 50% of the US recommended dietary allowance. These data show that vitamin A requirements are substantially increased during serious infections because of excretion of retinol in the urine, and suggest that these losses are due to pathologic changes associated with the febrile response.

Adult↗
PubMed1993

Vitamin A deficiency impairs some aspects of the host response to influenza A virus infection in BALB/c mice.

We examined the impact of vitamin A deficiency on the host response to an acute, viral infection of the respiratory tract by infecting BALB/c mice with a mouse-adapted strain of influenza A virus. Several indicators of the severity of infection were examined, including the rate of virus clearance from the lungs, the extent of inflammatory lesions, and percentage of survival. None of these was affected by vitamin A deficiency. Following the acute phase of infection, however, the regeneration of normal, respiratory epithelium was impaired and adenomatoid, metaplastic lesions developed within inflammatory foci in the lungs of deficient animals. The antibody response to infection was also characterized: the influenza A-specific immunoglobulin A (IgA) response in the respiratory tract was markedly decreased by vitamin A deficiency, but tracheal and lung lavage IgG titers were not affected. The serum IgM and IgG responses, and the serum hemagglutination-inhibition response, were also diminished by vitamin A deficiency. Decreased mucosal IgA titers and impaired regeneration of normal respiratory epithelium could impair recovery from a primary infection and increase susceptibility to opportunistic secondary infections.

Animals↗
PubMed1992

Prevalence of serum antibodies against lymphocytic choriomeningitis virus in selected populations from two U.S. cities.

An ELISA was developed for measuring serum antibodies against the arenavirus lymphocytic choriomeningitis virus (LCMV) and a closely related isolate termed callitrichid hepatitis virus (CHV). The ELISA was used to test sera from healthy adults and from hepatitis patients. In Birmingham, Alabama, the seropositivity rate for healthy black women was 5.1% (7/138), and the rate for patients with all types of hepatitis or cirrhosis was 4.3% (2/46). In San Antonio, Texas, the seropositivity rate among a clinical series of patients with non-A, non-B hepatitis was 0 (0/20), and the rate among persons rejected from blood donation because of high serum alanine aminotransferase levels was 2.4% (2/82). These results indicate that infection with LCMV or CHV is common in Birmingham but that infection is not associated with hepatitis.

Adult↗
PubMed1992

Monoclonal antibody solution hybridization assay for detection of mouse hepatitis virus infection.

A monoclonal antibody solution hybridization (MASH) assay was developed to detect fecal excretion of mouse hepatitis virus (MHV). The assay used a biotinylated cDNA probe to detect viral RNA target sequences by hybridization in solution, capture of hybrids on the solid phase with antibiotin antibody, and immunoassay with an enzyme-labelled monoclonal antibody specific for DNA-RNA hybrids. The MASH assay was used to monitor the time course of enterotropic MHV excretion after oronasal inoculation. Infectivity of the inoculated mice was simultaneously monitored with sentinel animals. The MASH assay detected MHV excretion in all inoculated mice, with the highest mean excretion levels occurring from day 3 through day 9 postinoculation. Mean excretion then decreased gradually to below detection limits by day 21 postinoculation. Sentinels became infected on exposure to inoculated mice up to but not after day 21 postinoculation. Infected sentinel mice showed a time course of virus excretion similar to that of inoculated mice. These results indicate that the MASH assay is useful for rapid, sensitive, and specific detection of MHV in clinical specimens from laboratory mice.

Animals↗
PubMed1992

Coronavirus species specificity: murine coronavirus binds to a mouse-specific epitope on its carcinoembryonic antigen-related receptor glycoprotein.

Like most coronaviruses, the coronavirus mouse hepatitis virus (MHV) exhibits strong species specificity, causing natural infection only in mice. MHV-A59 virions use as a receptor a 110- to 120-kDa glycoprotein (MHVR) in the carcinoembryonic antigen (CEA) family of glycoproteins (G. S. Dveksler, M. N. Pensiero, C. B. Cardellichio, R. K. Williams, G. S. Jiang, K. V. Holmes, and C. W. Dieffenbach, J. Virol. 65:6881-6891, 1991; and R. K. Williams, G. S. Jiang, and K. V. Holmes, Proc. Natl. Acad. Sci. USA 88:5533-5536, 1991). The role of virus-receptor interactions in determining the species specificity of MHV-A59 was examined by comparing the binding of virus and antireceptor antibodies to cell lines and intestinal brush border membranes (BBM) from many species. Polyclonal antireceptor antiserum (anti-MHVR) raised by immunization of SJL/J mice with BALB/c BBM recognized MHVR specifically in immunoblots of BALB/c BBM but not in BBM from adult SJL/J mice that are resistant to infection with MHV-A59, indicating a major difference in epitopes between MHVR and its SJL/J homolog which does not bind MHV (7). Anti-MHVR bound to plasma membranes of MHV-susceptible murine cell lines but not to membranes of human, cat, dog, monkey, or hamster cell lines. Cell lines from these species were resistant to MHV-A59 infection, and only the murine cell lines tested were susceptible. Pretreatment of murine fibroblasts with anti-MHVR prevented binding of radiolabeled virions to murine cells and prevented virus infection. Solid-phase virus-binding assays and virus overlay protein blot assays showed that MHV-A59 virions bound to MHVR on intestinal BBM from MHV-susceptible mouse strains but not to proteins on intestinal BBM from humans, cats, dogs, pigs, cows, rabbits, rats, cotton rats, or chickens. In immunoblots of BBM from these species, both polyclonal and monoclonal antireceptor antibodies that block MHV-A59 infection of murine cells recognized only the murine CEA-related glycoprotein and not homologous CEA-related glycoproteins of other species. These results suggest that MHV-A59 binds to a mouse-specific epitope of MHVR, and they support the hypothesis that the species specificity of MHV-A59 infection may be due to the specificity of the virus-receptor interaction.

3T3 Cells↗
PubMed1991

Isolation of an arenavirus from a marmoset with callitrichid hepatitis and its serologic association with disease.

Callitrichid hepatitis (CH) is an acute, often fatal viral infection of New World primates from the family Callitrichidae. The etiologic agent of CH is unknown. We report here the isolation of an arenavirus from a common marmoset (Callithrix jacchus) with CH by using in vitro cultures of marmoset hepatocytes and Vero-E6 cells. Enveloped virions 67 to 133 nm in diameter with ribosomelike internal structures were seen in infected cultures. Immunofluorescence and Western immunoblot analysis using CH-specific antisera (principally from animals exposed to CH during zoo outbreaks) revealed three antigens in cells infected with this CH-associated virus (CHV). These antigens had the same electrophoretic mobilities on sodium dodecyl sulfate-polyacrylamide gels as did the nucleocapsid, GP2, and GPC proteins of lymphocytic choriomeningitis virus (LCMV). Monoclonal antibodies specific for these arenavirus proteins also reacted with the three CHV antigens. Conversely, the CH-specific antisera reacted with the nucleocapsid, GP2, and GPC proteins of LCMV. CHV thus appears to be a close antigenic relative of LCMV. The serologic association of CHV with several CH outbreaks implicate it as the etiologic agent of this disease.

Animals↗
PubMed1990

Control of virus-induced cell fusion by host cell lipid composition.

Virus-induced cell fusion has been examined in a series of stable cell lines which were originally selected for resistance to the fusogenic effects of polyethylene glycol (PEG). For a wide variety of viruses, including murine hepatitis virus (a coronavirus), vesicular stomatitis virus (a rhabdovirus), and two paramyxoviruses (Sendai virus and SV5), susceptibility to virus-induced fusion was found to be inversely correlated with susceptibility to PEG-induced fusion. This phenomenon was observed both for cell fusion occurring in the course of viral infection and for fusion induced "from without" by the addition of high titers of noninfectious or inactivated virus. The fusion-altered cell lines (fusible by virus but not by PEG) are characterized by their unusual lipid composition, including marked elevation of saturated fatty acids and the presence of an unusual ether-linked neutral lipid. To test the association between lipid composition and fusion, acyl chain saturation was manipulated by supplementing the culture medium with exogenous fatty acids. In such experiments, it was possible to control the responses of these cells to both viral and chemical fusogens. Increasing the cellular content of saturated fatty acyl chains increased the susceptibility of cells to viral fusion and decreased susceptibility to PEG-induced fusion, whereas lowering fatty acid saturation had the opposite effect. Thus, parallel cultures of cells can be either driven toward the PEG-fusible/virus-fusion-resistant phenotype of the parental cells or rendered susceptible to viral fusion but resistant to PEG-induced fusion, solely by the alteration of cellular lipids. The ability of cellular lipid composition to regulate virus-induced membrane fusion suggests a possible role for lipids in viral infection and pathogenesis.

Animals↗
PubMed1990

Low gastric acid as a risk factor for cholera transmission: application of a new non-invasive gastric acid field test.

Although gastric acid is thought to be an important host defense against certain enteric infections, field studies of the role of gastric acid in preventing enteric infections have been hampered by the lack of a suitable non-invasive test. Because low gastric acid output (GAO) is an established risk factor for cholera, we assessed after validation, whether a new non-invasive test which estimates GAO by measuring breath hydrogen excess after ingestion of magnesium and a stimulant of gastric acid secretion, could discriminate between persons at high and at low risk of developing cholera. Fifteen age-matched pairs, participants in the field trial of two oral cholera vaccines in rural Bangladesh, were tested. In each pair the "case" was a person who had recovered from severe cholera at least 6 months before testing and the "control" was a person who resided in the home of a cholera patient but remained uninfected. The stimulated breath hydrogen was higher in controls (median hydrogen excess = 369 mumol/80 min) than in cases (median hydrogen excess = 150 mumol/80 min) (p less than 0.05) and was higher in controls in 12 out of 15 pairs. The results, which are consistent with past invasive assessments of the association between hypochlorhydria and cholera, suggest that this non-invasive test may be useful in evaluating GAO in epidemiological field studies.

Adult↗
PubMed1990

Identification, using sera from exposed animals, of putative viral antigens in livers of primates with callitrichid hepatitis.

Callitrichid hepatitis (CH) is an acute, frequently fatal viral hepatitis which affects members of the primate family Callitrichidae (R. J. Montali, E. C. Ramsay, C. B. Stephensen, M. Worley, J. A. Davis, and K. V. Holmes, J. Infect. Dis. 160:759-765, 1989; E. C. Ramsay, R. J. Montali, M. Worley, C. B. Stephensen, and K. V. Holmes, J. Zoo Wildlife Med. 20:178-183, 1989). Outbreaks of the disease occur in zoos and animal parks. In this study, CH-specific antigens were identified in the livers of infected animals by using immune sera from primates with CH and CH-exposed asymptomatic animals. Three CH-specific antigens with apparent molecular masses of 34, 54, and 65 kDa were identified. A polyclonal antiserum was raised against the 54-kDa antigen. These antigens were not found in the livers of uninfected animals and may be viral proteins. Our results suggest that at least five of the six outbreaks of CH considered here were caused by the same virus or by an antigenically related virus.

Animals↗
PubMed1989

A new transmissible viral hepatitis of marmosets and tamarins.

Callitrichid hepatitis (CH) is a newly recognized, acute, fatal, epizootic disease of New World primates in the family Callitrichidae. Since 1980, 12 outbreaks of CH have occurred in US zoos, involving several callitrichid species including the endangered golden lion tamarin (Leontopithecus rosalia). CH was experimentally transmitted to common marmosets via a bacteria-free filtrate of liver from a naturally infected tamarin. All three inoculated marmosets developed an acute fatal disease with the characteristic clinical and histopathologic findings of CH. Human hepatotropic viruses that can infect the livers of callitrichids were not detected serologically in any of the experimentally infected marmosets. Enveloped viruslike particles 85-105 nm in diameter were observed in the rough endoplasmic reticulum and Golgi complex of hepatocytes from both naturally infected and experimentally inoculated animals. An immunoblot assay was developed using sera from tamarins exposed to natural outbreaks of CH and liver extracts from experimentally infected or control marmosets. A new CH-specific antigen was detected in the livers of naturally infected and experimentally inoculated marmosets but not controls. These results suggest that the etiologic agent of callitrichid hepatitis is a new primate hepatitis virus.

Animals↗