Acute-phase Sera Of Patients Research Articles

Detection of anti-SFTSV nuclear protein antibody in the acute phase sera of patients using double-antigen ELISA and immunochromatography

Severe fever with thrombocytopenia syndrome (SFTS) is a life-threatening febrile illness that is caused by the SFTS virus (SFTSV). The diagnosis of SFTS is usually performed by detecting viral RNA. However, it has been reported that viral RNA is no longer detectable at 6–12 days after the onset of disease. In the current study, we have constructed a plasmid to express the recombinant nuclear protein (NP) based on the Japanese strain of SFTSV (J1). We developed a double-antigen enzyme-linked immunosorbent assay (ELISA) and immunochromatography (IC) assay using recombinant NP to detect antibody against SFTSV-NP. When we tested time-sequential samples from four patients with SFTS, antibody to SFTSV-NP were detectable not only during the recovery phase (days 10–622) but also during the acute phase (days 4–7) of the disease using both of a double-antigen ELISA and IC assay. SFTSV-RNA was detected until 8–11 days after onset, thus suggesting the coexistence of the virus and antibody during the acute phase of SFTS. These data suggest that assays for detecting antibody against SFTS-NP described in the current study may be applicable not only for the epidemiological studies but also for the diagnosis of SFTS.

Simultaneous detection and differentiation of dengue virus serotypes 1-4, Japanese encephalitis virus, and West Nile virus by a combined reverse-transcription loop-mediated isothermal amplification assay

BackgroundRapid identification and differentiation of mosquito-transmitted flaviviruses in acute-phase sera of patients and field-caught vector mosquitoes are important for the prediction and prevention of large-scale epidemics.ResultsWe developed a flexible reverse-transcription loop-mediated isothermal amplification (RT-LAMP) unit for the detection and differentiation of dengue virus serotypes 1-4 (DENV1-4), Japanese encephalitis virus (JEV), and West Nile virus (WNV). The unit efficiently amplified the viral genomes specifically at wide ranges of viral template concentrations, and exhibited similar amplification curves as monitored by a real-time PCR engine. The detection limits of the RT-LAMP unit were 100-fold higher than that of RT-PCR in 5 of the six flaviviruses. The results on specificity indicated that the six viruses in the assay had no cross-reactions with each other. By examining 66 viral strains of DENV1-4 and JEV, the unit identified the viruses with 100% accuracy and did not cross-react with influenza viruses and hantaviruses. By screening a panel of specimens containing sera of 168 patients and 279 pools of field-caught blood sucked mosquitoes, results showed that this unit is high feasible in clinical settings and epidemiologic field, and it obtained results 100% correlated with real-time RT-PCR.ConclusionsThe RT-LAMP unit developed in this study is able to quickly detect and accurately differentiate the six kinds of flaviviruses, which makes it extremely feasible for screening these viruses in acute-phase sera of the patients and in vector mosquitoes without the need of high-precision instruments.

Monoclonal Antibody-Based Antigen Capture Enzyme-Linked Immunosorbent Assay Reveals High Sensitivity of the Nucleocapsid Protein in Acute-Phase Sera of Severe Acute Respiratory Syndrome Patients

Accurate and timely diagnosis of severe acute respiratory syndrome coronavirus (SARS-CoV) infection is a critical step in preventing another global outbreak. In this study, 829 serum specimens were collected from 643 patients initially reported to be infected with SARS-CoV. The sera were tested for the N protein of SARS-CoV by using an antigen capture enzyme-linked immunosorbent assay (ELISA) based on monoclonal antibodies against the N protein of SARS-CoV and compared to 197 control serum samples from healthy donors and non-SARS febrile patients. The results of the N protein detection analysis were directly related to the serological analysis data. From 27 SARS patients who tested positive with the neutralization test, 100% of the 24 sera collected from 1 to 10 days after the onset of symptoms were positive for the N protein. N protein was not detected beyond day 11 in this group. The positive rates of N protein for sera collected at 1 to 5, 6 to 10, 11 to 15, and 16 to 20 days after the onset of symptoms for 414 samples from 298 serologically confirmed patients were 92.9, 69.8, 36.4, and 21.1%, respectively. For 294 sera from 248 serological test-negative patients, the rates were 25.6, 16.7, 9.3, and 0%, respectively. The N protein was not detected in 66 patients with cases of what was initially suspected to be SARS but serologically proven to be negative for SARS and in 197 serum samples from healthy donors and non-SARS febrile patients. The specificity of the assay was 100%. Furthermore, of 16 sera collected from four patients during the SARS recurrence in Guangzhou, 5 sera collected from 7 to 9 days after the onset of symptoms were positive for the N protein. N protein detection exhibited a high positive rate, 96 to 100%, between day 3 and day 5 after the onset of symptoms for 27 neutralization test-positive SARS patients and 298 serologically confirmed patients. The N protein detection rate continually decreased beginning with day 10, and N protein was not detected beyond day 19 after the onset of symptoms. In conclusion, an antigen capture ELISA reveals a high N protein detection rate in acute-phase sera of patients with SARS, which makes it useful for early diagnosis of SARS.

Rapid and sensitive streptavidin‐biotin amplified fluorogenic enzyme‐linked immunosorbent‐assay for direct detection and identification of dengue viral antigens in serum

Each of the four serotypes of dengue viruses is responsible for a spectrum of illnesses that range from nonspecific febrile syndrome with good prognosis to dengue haemorrhagic fever or dengue shock syndrome. Definite diagnosis of dengue is provided by the detection of virus in acute-phase sera of patients. Virus isolation can be accomplished with mosquito cell lines or mosquito inoculations. However, these methods are time consuming and labour intensive. The reverse-transcriptase polymerase chain reaction (RT-PCR) provides a potential means of rapid diagnosis but requires specialised facilities and equipment and is expensive. Therefore a rapid, simple, sensitive, and economical method for direct detection of viral antigens in viraemic sera is needed for clinical and epidemiological investigations. An amplified fluorogenic enzyme-linked immunosorbent assay (F-ELISA) is described for the detection and identification of dengue-3 viruses in serum specimens. This assay utilizes biotinylated mouse IgG antibody directed against dengue antigens captured by anti-dengue monoclonal antibody coated onto polystyrene microplate wells. It takes advantage of the high affinity of biotin for the multivalent binding sites of streptavidin-labelled beta-galactosidase, and combines the amplification effect of biotin-streptavidin interaction with the high sensitivity of fluorogenic detection methods. Following optimisation of the procedure by reducing non-specific binding of proteins and enhancing the specific binding of antigens, F-ELISA was tested on 259 sera submitted routinely to our laboratory for confirmation of dengue diagnosis. The sensitivity of the F-ELISA was 90%, the specificity was 99% and the agreement rate was 98% between F-ELISA and virus isolation results.

Immunoglobulin subclass distribution and binding characteristics of anti-GQ1b antibodies in Miller Fisher syndrome.

Circulating IgG antibodies to carbohydrate determinants on GQ1b ganglioside are found in the acute phase sera of patients with Miller Fisher syndrome, a variant of Guillain-Barré syndrome. Here we report that the IgG subclass distribution of the anti-GQ1b antibodies is mainly restricted to IgG1 and IgG3 antibodies, subclasses typically associated with a T cell-dependent immune response to protein antigens. This is highly unusual in that IgG responses to carbohydrate determinants are typically of the IgG2 subclass. Anti-GQ1b antibodies also have a limited ability to bind GQ1b in a membrane-like environment, particularly at body temperature. These data suggest that the antigen initiating the immune response in MFS is not likely GQ1b but an unidentified cross-reactive glycoprotein antigen(s). Similar results were obtained for anti-GM1 IgG antibodies in Guillain-Barré syndrome.

Adenovirus infection in patients with Kawasaki disease

Two outbreaks of Kawasaki disease at different times and areas (Kyoto in 1982 and Sapporo in 1985) of Japan were studied retrospectively for the presence of antibodies to adenoviruses and herpesviruses. Only 2 of 12 (16.7%) consecutive acute phase sera of patients from the outbreak in 1982 and 1 of 10 (10.0%) sera from 1985 showed positive antibodies for the common adenovirus antigen by a complement fixation (CF) test, whereas 10 of 16 (62.5%) age- and sex-matched controls during the outbreak of Kawasaki disease in 1985 were seropositive by the CF test. In contrast, using a recently developed enzyme-linked immunosorbent assay (ELISA), 9 patients (75.0%) in 1982 and 9 patients (90.0%) in 1985 had antibodies to adenovirus type 2. In addition, 5 of 10 (50.0%) of the 1982 and 6 of 9 (66.7%) of the 1985 patients who were seronegative for CF antibodies were positive for IgM antibodies to adenovirus type 2. Fifteen (93.8%) controls were positive for antibodies to adenovirus type 2 by ELISA and only two sera showed negative CF antibodies with positive IgM antibodies to adenovirus type 2. Sequential sera from 4 patients in 1985 had either IgM or IgG antibodies by ELISA and eventually three became seropositive by the CF test in time. Additionally, no significant difference was noted with antibody status to herpes simplex virus type 1 and 2 (HSV-1 and HSV-2), varicella zoster virus (VZV), and cytomegalovirus (CMV) between patients and controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies to Lipopolysaccharide in the Acute-Phase Sera of Patients with Meningitis Due to Haemophilus influenzae Type b

Antibodies to Lipopolysaccharide in the Acute-Phase Sera of Patients with Meningitis Due to Haemophilus influenzae Type b

Hepatitis-associated antigen in chimpanzees.

The hepatitis-associated antigen, or Australia antigen, is rarely found in sera collected randomly from normal populations of the United States, but it appears with high frequency in acute-phase sera of patients with long-incubation-period hepatitis [1,2]. Inoculation of such serum into human volunteers has been followed by hepatitis in these individuals [3]. However, failure to demonstrate nucleic acid in purified preparations of the antigen indicates that it may not itself be the virus of longincubation-period hepatitis, but rather some component of the viral particle or a secondary byproduct of viral multiplication [4]. Hirschman and colleagues have detected hepatitis-associated antigen in two of 128 healthy chimpanzees by the technique of agar-gel diffusion [2], and Prince found antigen by the same method in eight of 138 chimpanzees. He also detected antibody to the antigen in the serum of six separate animals [5]. In both studies, the qualitative identity of the simian antigen with human antigen was established by agar-gel diffusion. The occurrence of viral hepatitis in chimpanzees imported into this country has been well documented [6]. The clinical, histopathologic, and chemical features of this illness are similar to those seen in man [7], and the disease may be transmitted from chimpanzees to humans [8, 9]. Since 1963, the Phoenix Laboratories of the Center for Disease Control has housed successive cohorts of chimpanzees for research on hepatitis and related problems. Intensive surveillance of illness, including serial bleedings and biopsies of livers, allowed evaluation of the incidence and duration of viral hepatitis in these animals. Avail-

Recovery of rubella virus from army recruits.

SummaryA virus recognized by its capacity to multiply in grivet monkey kidney cultures and to interfere in such cultures with subsequent multiplication of ECHO-11 virus, was isolated regularly from military recruits with rubella, but rarely from those hospitalized at the same time and place with scarlet fever. The newly recovered virus multiplied consistently in primary and continuous grivet kidney cultures. The virus was filterable, sensitive to heat and organic solvents, and immunologically distinct from a number of other chloroform sensitive agents. Neutralizing antibody often was present in acute phase sera of patients with rubella and regularly increased significantly during convalescence in patients yielding the virus.

The Response to Influenza Vaccines as Determined by Levels of Complement-Fixing Antibody in the Acute-phase Sera of Patients with Respiratory Disease

Summary Sera examined within 4 days of the onset of a respiratory illness showed no effect on CF antibody titers to influenza virus even though many of the cases were influenza A. The effect of preceding influenza A infections was detectable, but after, not during, the peak of an outbreak of influenza. In men who had received type-specific influenza vaccines, an approximate evaluation of the CF antibody response to the vaccines could be obtained. An A′ vaccine, containing two strains, was shown to stimulate CF antibody 7–8 days after vaccination, and a probable peak response at 9–10 days. The effect persisted for 1 month and was equivocally present for 2 more months. An influenza B vaccine of the same chick cell agglutination (CCA) unitage but containing only one strain, produced a greater and apparently less sharply peaked response, which lasted longer.