Evaluation of a new immunodiagnostic assay for Helicobacter pylori antibody detection: correlation with histopathological and microbiological results.

Infection with Helicobacter pylori has been associated with the pathogenesis of chronic active gastritis and gastric and duodenal ulcer disease. Detection of immunoglobulin G antibodies to H. pylori offers a simple alternative to direct detection of the organism in biopsied tissue by culture or histopathological methods. A rapid flow-through membrane-based enzyme immunoassay for the detection of human immunoglobulin G antibodies to H. pylori has been developed and evaluated. Clinical evaluations were performed with 256 patient serum samples obtained from four clinical sites. Biopsy samples were obtained by endoscopic procedures at the same time as the serum samples, and were histopathologically and microbiologically categorized for the presence or absence of H. pylori. Sensitivity and specificity for this rapid enzyme immunoassay were 92 and 88%, respectively, compared directly with endoscopy results. After discordant results were resolved by a quantitative microwell enzyme-linked immunosorbent assay, the resulting sensitivity and specificity were 94 and > 99%, respectively. These results indicate that this rapid enzyme immunoassay is a useful technique to determine H. pylori infection status and is a viable alternative to invasive endoscopic procedures.

Chemiluminescent immunoenzymatic assay for rapid diagnosis of viral infections.

Current methods of viral diagnosis have been criticized for slowness and insensitivity. However, immunoassay may provide the desired increase in the speed of diagnosis without sacrificing accuracy. This report describes the efficacy of the detection of viral antigen by means of an absorptiometric enzyme-linked immunoassay (ELISA) or by a chemiluminescent enzyme-linked immunoassay (CELISA). Human cytomegalovirus was detected in clinical specimens or culture fluid with comparable sensitivity by CELISA and by viral isolation but with 50 times lesser sensitivity by ELISA. Similarly, herpes simplex virus was detected in clinical specimens with markedly greater sensitivity by CELISA than by ELISA. These findings indicate that the detection of appropriate viruses by CELISA may be a practical alternative to their isolation in cell culture.

Effect of acyclovir on genital infection with herpes simplex virus types 1 and 2 in the guinea pig.

The pathogenesis of genital infection with three different strains of herpes simplex virus type 1 (HSV-1) and three strains of herpes simplex virus type 2 (HSV-2) was compared in the guinea pig. Strain differences in severity of clinical disease and mortality were noted. HSV-1 strains generally produced milder disease than HSV-2. Both HSV-1 and HSV-2 infections resulted in acute and chronic changes in the cervix. Virus recovery during latent infection was more frequently obtained from the spinal cord in HSV-1-infected animals and from lumbosacral ganglia in HSV-2-infected animals. Systemic treatment with acyclovir, after the onset of clinical disease, had minimal, if any, effect on genital infection with HSV-1 (NYU-78), but similar treatment of HSV-2 (WT-186) infection resulted in decreased lesion scores, paralysis, and mortality during acute infection. A reduction in virus isolations from lumbosacral ganglia was noted during both acute and latent infection with HSV-2 (WT-186) in the acyclovir-treated groups.

Effect of acyclovir on genital herpes in guinea pigs.

The chemotherapeutic efficacy of acyclovir was evaluated in guniea pigs that were inoculated intravaginally with herpes simplex virus type 2 (HSV-2). Acyclovir was administered systemically (50 mg/kg of body weight per day ip) beginning three days after inoculation and continuing for 10-11 days. Treatment with acyclovir reduced the incidence of paralysis of the hind limbs, mortality, and the severity and duration of genital lesions but had little effect on the excretion of virus from the genital tract. Recovery of HSV-2 from neural tissues of infected animals during latent infection was less frequent in acyclovir-treated animals than in untreated ones. These data suggest that acyclovir may be a promising drug for altering the severity of clinical genital herpes in humans during acute infection and reducing the incidence of viral latency following primary infection.

Comparison of chemiluminescence and absorptiometry in enzyme immunoassays for protein quantification.

The use of chemiluminescence in competitive binding assays for human serum albumin, human alpha-fetoprotein and human immunoglobulin G and in double antibody sandwich enzyme immunoassays for cytomegalovirus and herpes simplex virus increased the sensitivity of the detection of antigen or antibody 16- to 95-fold above that obtained by conventional absorptiometric methods.

Serologic evidence of avian adeno-associated virus infection in an unselected human population and among poultry workers.

Six (6.0%) of 100 serum samples from an unselected adult population were positive for antibody to avian adeno-associated virus (A-AV) by agar gel precipitation (AGP), and 10 (15.6%) of 64 were positive by virus neutralization (VN). Three (14.3%) of 21 samples from poultry workers (industry or research) were positive for avian A-AV antibody by AGP and 14 (66.7%) of 21 were positive by VN. All sera positive by AGP were also positive by VN. Twenty-two of 244 sera positive for antibody to avian A-AV by VN were positive for human adenovirus antibody. None of the sera were positive for avian adenoviral antibody by AGP. No cross reaction was noted by AGP when antiserum to avian A-AV was reacted against primate antigens of serotypes 1-4 or when antiserum to A-AV serotypes 1-14 were reacted against avian A-AV antigen. Antiserum prepared against primate A-AV serotypes 1-4 did not neutralize the avian A-AV. These results suggest that avian A-AV infections are not restricted to avian species but are found in the human adult population.

Sensitive chemiluminescent enzyme-linked immunosorbent assay for quantification of human immunoglobulin G and detection of herpes simplex virus.

A chemiluminescent enzyme-linked immunosorbent assay (CELISA) was developed for detecting human immunoglobulin G and herpes simplex viral antigen. A comparison of CELISA with a conventional absorptiometric detection system showed that CELISA was 100 times more sensitive than absorptiometry for the measurement of human immunglobulin G. Similarly, CELISA detected as few as 40 plaque-forming units of herpes simplex virus in contrast to 2,500 plaque-forming units detected by absorptiometry. Of 18 specimens which were positive for herpes simplex virus type 1 by isolation in tissue culture, 15 (83%) were detected by CELISA within a few hours; in certain cases, several days were necessary for detection of virus by isolation techniques.

Enhancement and inhibition of CELO virus pathogenicity in quail by avian adenovirus-associated virus.

Dual infection of 12 day-old quail (Colinus virginianus) with 10(6) plaque forming units of CELO virus and low doses of avian adeno-associated virus (A-AV), resulted in significant enhancement of CELO virus-induced mortality, whereas dual infections with high doses of A-AV resulted in a delay in mortality. A-AV induced enhancement and inhibition of CELO virus pathogenicity could be blocked by the addition of A-AV antiserum prior to infection.

An enzyme-linked immunosorbent assay for detection of antibodies to avian adenovirus and avian adenovirus-associated virus in chickens.

An enzyme-linked immunosorbent assay system (ELISA) was adapted for the detection of antibodies to avian adenovirus (AV) and avian adenovirus-associated virus (A-AV). Both before and after exposure, sera from chickens undergoing natural and experimental infections were assayed by ELISA, virus neutralization (VN), and immunodiffusion (ID) for antibody to both CELO virus and A-AV. The ELISA system was found to be comparable to VN for determining antibody concentrations to CELO virus and A-AV. In many cases, ELISA was found to be more sensitive than ID.

Populations of infectious virus produced during avian adenovirus-associated virus infection.

Multiple rounds of infection in vitro or in vivo with avian adenovirus-associated virus (AvA-AV) and avian adenovirus (AvAV) result in production of both heavy (H) and light (L) infectious forms. In this study, the infectious AvA-AV progeny produced at different hours during recombined dual infection of cells with either H or L AvA-AV and AvAV was determined by equilibrium CSCl centrifugation and infectivity assay. In both types of infection, H virions were found early, both intra- and extracellularly, whereas L virions were found late. The data iondicate an H to L particle density shift during infection. Virus-specified cell-dependent factors mediated the process extracellularly, as activity was detected in infected cell-conditioned medium and in lysates of infected cells but not in medium or components of uninfected cells. The shift in density was accompanied by a conversion in particle type. H and L virions differed in size and conformation as evidenced by differences in serological cross-reactivity and physical-chemical stability during heat inactivation, ultrasonic disruption and DNA extraction.

Egg transmission of avian adenovirus-associated virus and CELO virus during a naturally occurring infection.

Both avian adenovirus-associated virus (A-AV) and CELO virus were isolated from the embryonating eggs of 25-week-old black sex-linked hens during a naturally occurring infection. In the first 7 days of egg collection, A-AV was isolated from 10 of 43 (23.2%) embryonating eggs, and CELO virus was isolated from 8 of 43 (18.6%) embryonating eggs. Both viruses were isolated from six eggs. In the next 16 days of egg collection, A-AV and CELO virus were coisolated from 1 of 127 (0.8%) eggs; all other samples were negative for both viruses. All six hens transmitting A-AV to eggs and 5 of 6 hens transmitting CELO virus showed seroconversions (fourfold increase in antibody concentrations). Viruses were not isolated from eggs after the hens showed a fourfold increase in antibody concentrations.

Inhibition and enhancement of avian adenovirus plaque production by heavy and light avian adenovirus-associated viral particles.

The effect of heavy and light avian adenovirus-associated viral (A-AV) particles on the replication of several adenovirus serotypes was studied in chicken embryo kidney cells. There was a significant decrease (P less than 0.05) in the number and size of adenovirus-induced plaques at A-AV multiplicities of infection greater than 40. Enhancement of plaque production was observed when A-AV multiplicities of infection were 1 to 40. There was a significant increase in the number and size of infective centers. Analysis of cellular yields indicated an increase in the number of adenoviruses produced per cell. Heavy A-AV particles of buoyant density 1.42 g/cm3 in CsCl were found to enhance plaque production more than light particles (1.38 g/cm3). Conversely, light particles showed greater inhibition of plaque production. Adenovirus serotypes varied in their response to enhancement or inhibition by A-AV particles of different density.

Effect of avian adeno-associated virus on pathogenicity of Tipton virus in chicks.

The avian adeno-associated virus (A-AV) reduced the pathogenicity of an adenovirus infection in vivo. Groups of chicks were infected with Tipton virus alone or in combination with high or low doses of A-AV. In both trials, the associated virus delayed and reduced chick mortality. This effect was dose-dependent and significant at the higher dose level.