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PubMed1998

Loss maternally derived measles immunity in Argentinian infants.

BACKGROUND: Measles immunization of children at 1 year of age with a single dose of the current vaccine has successfully reduced measles incidence in Argentina. However, the optimal schedule of measles vaccination of young infants would balance the risk of early loss of maternal antibody in the majority of infants with the risk of primary vaccine failure because of passive measles immunity. This study is the first to document a significant association between loss of passive measles antibody and age among infants born in 1995 and 1996 in Córdoba City, Argentina. METHODS: This is a seroprevalence study of 340 infants to investigate the duration of transplacentally derived measles antibody, assayed by a neutralization test, during the first 8 months of age in Córdoba City, Argentina. RESULTS: The proportion with detectable neutralizing measles antibodies decreased from 85% at 1 month of age to 8% at 8 months of age. The simple logistic model with age (in weeks) as the only variable showed that the decline in the proportion of infants with a positive antibody titer was sharpest during the second and fifth months of age (6.6 and 6.8% per week during a 4-week period, respectively). CONCLUSIONS: These findings suggest that 80% of infants are susceptible to measles infection for at least 3 months before routine immunization at 12 months of age.

Aging↗
PubMed2005

Long-term studies on maternal immunity for Aujeszky's disease and classical swine fever in wild boar piglets.

The aim of the studies was to fathom the duration and the role of maternal immunity for Aujeszky's disease (AD) and classical swine fever (CSF) in wild boar offspring. In one experiment, two wild boar sows were infected with a low pathogenic pseudorabies virus (PRV) in 1999. A total of 51 offspring was born between 1999 and 2002 and was monitored for PRV maternal antibodies. In a second experiment, the maternal immunity for CSF was analysed. Therefore, a sow was orally vaccinated against CSF using vaccine baits containing the live-attenuated C-strain vaccine. The vaccination took place in January 1999. The sow gave birth to four piglets in 2001 and to two piglets in 2002. With respect to maternal immunity for AD, some piglets reacted positive in the ELISA up to 27-week post-partum while in the neutralization test antibodies were detected up to 15-week post-partum. The calculated half-life of neutralizing antibodies was 21 days. Regarding CSF, the neutralization titres of maternal antibodies dropped continuously reaching values of < or =10 ND50 20-week post-partum. After the 12th week post-partum, most of the sera reacted negative in the ELISA. However, after the third month, low levels of neutralization titres were still detectable. The results are discussed with respect to the epidemiology and control of both diseases in wild boar populations.

Animals↗
PubMed2004

Immunogenicity of an inactivated oil-emulsion canine distemper vaccine in African wild dogs.

The immunogenicity of an inactivated oil-emulsion vaccine against canine distemper virus was evaluated in nine captive African wild dogs (Lycaon pictus). Antibody levels were determined by neutralization test in Vero cells. No significant local or systemic adverse reactions were observed in the animals. Virus neutralizing antibody levels >1:20 were detected, especially in animals that were vaccinated twice. The use of oil adjuvants is suggested as a good way to enhance the immune response to inactivated canine distemper vaccine.

Animals↗
PubMed1990

A new approach for the diagnosis of hog cholera.

Pestiviruses were isolated from seven cases of suspect hog cholera. Using peroxidase conjugates of monoclonal antibodies (Mabs) six isolates were identified as hog cholera viruses (HCV), while one isolate was of ruminant origin, possibly bovine viral diarrhea virus. In parallel attempts were made to develop an ELISA for the detection of HCV-specific antibodies in pig sera. The Mab HCTC26 coated to polystyrol plates efficiently captured the major viral glycoprotein gp53 from crude antigen suspensions prepared from infected cells. The immobilized gp53 served as diagnostic antigen. Five pigs experimentally infected with the HCV strain Glentorf were sequentially bled and the development of antibodies was monitored by neutralization tests and the ELISA. Results showed that both tests detected antibodies simultaneously after infection. Titres measured by ELISA were slightly higher than those registered by neutralization.

Animals↗
PubMed1981

Immune complexes in syphilis sera.

Four hundred and forty-nine syphilis sera, positive in VDRL and FTA-ABS tests, were studied for the presence of circulating immune complexes (CIC) by means of anti-antibody (AA) neutralization test. Ninety-three (20.7%) sera had demonstrable CIC. Subsequently, dispersion of CIC by saline suspension of cardiolipin and by extract of rabbit testicular syphiloma was examined. Of 40 CIC-containing sera tested with cardiolipin, dispersion of CIC was noted in 16 instances; of 32 CIC-containing sera examined with syphiloma extract, dispersion was noted in 16 cases. Significantly, CIC that showed definite dispersion by cardiolipin were not dispersed by syphiloma extract and vice versa. Some studies were also performed on lepromatous leprosy and SLE. None of 27 cIC-containing lepromatous leprosy sera were affected by cardiolipin, but in 2 of 9 CIC-containing SLE sera, cardiolipin dispersed the complexes. Cardiolipin-anti-cardiolipin complexes that neutralized AA were frequently observed when cardiolipin was added to sera containing its corresponding antibodies but not CIC. Similar reactions were noted between the syphiloma extract and anti-treponemal antibodies.

Animals↗
PubMed1986

Purification and characterization of an Aeromonas hydrophila hemolysin.

A hemolysin produced by Aeromonas hydrophila CA-11, isolated from an environmental source, was purified by sulfopropyl-Sephadex C-25 chromatography at pH 5.0. This hemolysin caused fluid accumulation in infant mouse intestines and rabbit intestinal loops and killed Vero cells, as did the hemolysin produced by strain AH-1, isolated from a diarrheal case. In polyacrylamide gel electrophoreses at pHs 4.0 and 9.4 and in thin-layer isoelectric focusing, CA-11 hemolysin migrated as a single band to a position different from that of AH-1 hemolysin. Immunodiffusion tests indicated that CA-11 hemolysin was immunologically related to AH-1 hemolysin but possessed unique antigenic determinants. Neutralization tests with antihemolysin sera also demonstrated immunological cross-reactivity between AH-1 and CA-11 hemolysins. These results apparently indicate that the hemolysins produced by the two strains of A. hydrophila are immunologically and physicochemically different from each other.

Aeromonas↗
PubMed1990

Recurrent herpetic keratitis: failure to detect herpes simplex virus infection using the Syva MicroTrak HSV1/HSV2 direct specimen identification/typing test.

A 35-year-old man had developed recurrent herpetic keratitis characterized by dendritic keratitis at intervals of a year. We were able to culture cytopathic agents repeatedly from his lesions by inoculating Vero cells. The cultures yielded definitive evidence of a virus that caused a cytopathic effect within 3 days. However, these virus strains could not be identified as herpes simplex virus (HSV) in immunofluorescence assays using the Syva MicroTrak HSV1/HSV2 direct specimen identification/typing test. Rather they were identified as strains of HSV type 1 (HSV-1) on the basis of plaque morphology, neutralization tests, electron-microscopic examination and DNA restriction endonuclease analysis. Our results allow us to assume the existence of HSV-1 strains isolated clinically that are negative to analysis using the Syva Micro-Trak HSV1/HSV2 direct specimen identification/typing test.

Adult↗
PubMed2003

Neutralization of measles virus infectivity and antibody-dependent cell-mediated cytotoxicity activity against an Epstein-Barr virus-infected cell line by intravenous immunoglobulin G [corrected].

Patients with antibody deficiency disorders are highly susceptible to microbial infections. Intravenous (i.v.) immunoglobulin concentrates were originally developed as replacement therapy for such patients. The present study assesses the measles virus neutralizing antibody titers and the antibody-dependent cell-mediated cytotoxicity (ADCC) capacities against Epstein-Barr virus (EBV)-infected cells of immunoglobulin G (IgG) preparations produced for i.v. use (i.v. IgG). The level of neutralizing antibodies against measles virus was determined by a syncytium neutralization test with Vero cells as targets. The measles virus neutralizing antibody titers of the i.v. IgG preparations were >3 x 10(2) and were an average of 1.0 log higher than the titers in pooled plasma from healthy subjects. The two IgG preparations tested showed similar ADCC activities against EBV-infected Raji cells, being active at concentrations of 3 mg/ml or higher. i.v. IgG bound to Raji cells but not to the EBV-negative Ramos cells, as evaluated by flow cytometry. Our in vitro findings may provide further support for the use of i.v. IgG for the prevention and treatment of infections caused by specific viral pathogens.

Animals↗
PubMed1983

Detection of factor IX inhibitors by immunoradiometric assay.

An immunoradiometric assay (IRMA) for the determination of factor IX inhibitors in haemophilia B was developed. The assay was based on competitive binding between radiolabelled anti-IX and inhibitors in the test material of immobilized IX:C. 5 haemophiliacs with known inhibitors were investigated with the new method and with a conventional neutralization test. An inhibitor titre as low as 5 X 10(-4) U/ml could be measured by IRMA, showing it to be about 500 times as sensitive as the conventional neutralization assay used, and in 2 cases the inhibitors could only be detected by IRMA. The new method is thus useful for the investigation of patients with low inhibitor titres, or when inhibitors with divergent properties are suspected.

Antibodies↗
PubMed1984

[Trials to obtain conjugates for the passive hemagglutination test with chromium chloride and their use in studying foot-and-mouth disease viruses].

Experiments were carried out to produce conjugates for the hemagglutination-inhibition reaction with the aid of chromic chloride. Studies with reference F.M.D. viruses and with CFT revealed that the antibody erythrocyte diagnostic agents were highly specific, and were stable in storage at +4 degrees C and in freeze-drying. It was found that the conjugates obtained with F.M.D. antigens possessed high specificity, however, were not stable and 7 to 10 days later lost their activity. Tests with the hemagglutination-reaction showed that immunity itself could be studied in cattle treated with F.M.D. vaccines. A correlation was found between the results obtained via the hemagglutination reaction and those obtained with the aid of the virus-neutralization test.

Animals↗
PubMed1976

Measles virus infection and multiple sclerosis: serological studies.

In 159 patients out of 161 with multiple sclerosis (MS), a significant rise in the level of measles hemagglutination inhibition (HI) antibody was found in the serum and in 92 MS patients the occurrence of measles HI antibody in the CSF was significantly more frequent. MS patients showed CSF humoral response against measles virus by neutralizing test (NV) (76%) more often than by hemagglutination test (37%). CSF FA antibody was found in 60%. In the serum of MS patients the presence of NV, HAd, FA, and GP-RNP was observed. 87% of MS patients showed lowered serum: CSF NV or HI antibody ratios and 78% had a diminished FA antibody ratio. Longitudinal study of serum HI measles virus antibody showed no substantial changes over longer period of the disease. Higher CSF measles antibody titer was found in more disabled patients with a malignant course of the disease (P less than 0.001). It is concluded that either persistent infection with proviruses or nonspecific stimulation of certain clones in individuals with genetic susceptibility provides for an excessive synthesis of humoral viral antibodies in MS.

Adolescent↗
PubMed1985

Trypanosoma brucei: immunogenicity of the variant surface coat glycoprotein of virulent and avirulent subspecies.

Comparative analyses were made to define the immunogenic role in mice of the variant surface coat glycoprotein (VSG) of African trypanosomes. Less than 10 micrograms of the glycoprotein fixed to trypanosomes or covalently linked to sheep erythrocytes were 100 times more immunogenic than soluble VSG. Therefore, although VSG is present on the parasites and in the blood of infected hosts, the cell-bound form most likely elicits immunity. Intravenous administration of soluble or cell-bound VSG was a better route of immunization than the subcutaneous route. Therefore, although parasites grow at the site of infection, in tissue spaces, and in the blood, control of blood parasitemia is best developed if the antigen is introduced to the vascular bed. Full protection against homologous challenge occurred by 4 days and was maintained through 30 days. Trypanosome-agglutinating antibody titers could be measured at 3 days, peaked at 5 days, and remained high through 14 days after immunization. Therefore, mice immunized with an optimal dosage of VSG, 2 days before challenge, should have had ample time to elicit a protective response. Most of these mice, however, developed patent infections, and one-third died during the first peak of parasitemia at about the same time as untreated control mice. This indicates that active infection inhibits the early phases of induction of immunity. Mice, suboptimally immunized against and challenged with an avirulent isolate of Trypanosoma brucei gambiense, survived at higher rates than mice immunized and challenged with a virulent clone of T. b. rhodesiense. Cell-fixed and soluble VSG from both parasites elicited similar agglutinating-antibody titers, indicating that the two trypanosomes were equally antigenic. Results from neutralization tests, however, revealed that, per unit of immune mouse serum, 400 times more T. b. gambiense became noninfective than T. b. rhodesiense. Apparently, virulence is related to relative sensitivity of the trypanosomes to immunological assault.

Agglutination Tests↗
PubMed1972

Antibody responses and resistance to challenge in volunteers vaccinated with live attenuated, detergent split and oil adjuvant A2-Hong Kong-68 (H 3 N 2 ) influenza vaccines. A report to the Medical Research Council Committee on Influenza and other Respiratory Virus Vaccines.

Forty-nine subjects were vaccinated with either live attenuated, detergent split, or oil adjuvant A2/Hong Kong influenza vaccines, or a saline influenza B vaccine as control. Respiratory symptoms occurred more frequently in subjects who received the live vaccine but in total there was little difference between the symptoms in the four groups. Antibody titres in nasal washings and serum were measured by haemagglutination inhibition, neuraminidase inhibition and virus neutralization tests. The oil adjuvant vaccine stimulated larger antibody responses than the other procedures. Six weeks after vaccination the volunteers were challenged with partially attenuated live A2/Hong Kong influenza virus administered intranasally. The live attenuated and oil adjuvant vaccines provided the best protection against challenge.

Adjuvants, Immunologic↗
PubMed1990

Epitope analysis of the envelope and non-structural glycoproteins of Murray Valley encephalitis virus.

Previous studies have shown that antibodies produced against strategic flavivirus epitopes play an important role in recovery and immunity. Definition of the conformation and location of these epitopes and the degree of their conservation among flaviviruses is important to understanding the humoral response to flavivirus infection. In this study we have examined epitopes recognized by 14 monoclonal antibodies (MAbs) produced to the envelope (E) and non-structural (NS1) proteins of Murray Valley encephalitis virus (MVE). These antibodies were analysed for specificity, neutralization, haemagglutination inhibition (HI) and competitive binding. We have identified six distinct epitopes on the E protein which are located in four non-overlapping domains. MAbs to epitopes in one domain neutralized virus, were specific for MVE and Japanese encephalitis virus, and reacted with epitopes resistant to reduction. Two other E domains, one specific to MVE and the other shared by all flaviviruses, also contained neutralization sites and were stabilized by disulphide bonds. The fourth domain on E was conserved among the flaviviruses, sensitive to SDS denaturation and did not induce neutralizing antibody. Studies with MVE NS1 MAbs revealed that they were mostly type-specific, unreactive with conserved epitopes, and unreactive in HI and neutralization tests. The six epitopes identified on NS1 did not overlap and represent antigenic domains either resistant or sensitive to reduction. Immunoblotting of viral proteins in MVE-infected C6/36 cells revealed two distinct forms of NS1 and high Mr proteins of 97K and 108K that represented disulphide-linked heterodimers of E and NS1.

Animals↗
PubMed2003

Antibody responses determined for Japanese dengue fever patients by neutralization and hemagglutination inhibition assays demonstrate cross-reactivity between dengue and Japanese encephalitis viruses.

Titers of antibodies to infecting dengue virus serotypes determined by serum neutralization assay were higher than those of antibody to Japanese encephalitis (JE) virus in Japanese dengue patients after disease day 8. Titers of antibody to dengue virus antigens determined by hemagglutination inhibition (HI) assay were higher in only 1 of 23 serum specimens after disease day 11. Thus, the neutralization test is more reliable than the HI test for serological diagnosis of dengue in countries where JE vaccination is widely used or JE is endemic.

Adolescent↗
PubMed1990

Polypeptide specificity of antiviral serum antibodies in children naturally infected with human rotavirus.

Reassortants between serotype 3 SA11 and serotype 6 NCDV rotaviruses were used to determine the relative amounts of serum-neutralizing antibody to VP4 and VP7 of serotype 3 SA11 rotavirus in children after natural rotavirus exposure. Sera from Ecuadorian children of a population-based study and sera from children of a hospital-based study in Germany (excluding diarrhea patients) demonstrated high titers of VP7-specific but only low titers of VP4-specific antibodies. In contrast, paired sera from German children hospitalized with a symptomatic primary rotavirus gastroenteritis demonstrated a titer increase to VP4 more frequently than to VP7 protein by neutralization test and immunoblotting. For these rotavirus patients, we provided, previously, direct evidence for the development of cross-neutralizing antibodies.

Antibodies, Viral↗
PubMed2025

Clinical and laboratory profiles of Oropouche virus disease from the 2024 outbreak in Manaus, Brazilian Amazon.

BACKGROUND: The 2024 Oropouche virus (OROV) outbreak in Brazil raised public health concerns due to its unprecedented rapid spread, high incidence, and potential neurological complications. OROV symptoms overlap with locally endemic arbovirus diseases, like dengue virus (DENV), complicating diagnosis. The study aimed to compare clinical, laboratory, and immunological profiles in OROV and DENV cases, crucial for improving diagnosis and management. METHODS: This study analyzed 51 OROV and 78 of DENV cases consecutively enrolled in Manaus, Amazonas, Brazil, and monitored for 28 days. OROV diagnosis was performed by real-time PCR (RT-PCR) using serum and urine samples. OROV RT-PCR positive samples were genotyped. A paired Plaque Reduction Neutralization Test (PRNT) was conducted on samples collected at D1 and D28. Patients with a&#x2009;&#x2265;&#x2009;4-fold increase in neutralizing antibody titer between D1 and D28 were considered OROV-positive. Clinical manifestations, hematology, biochemistry, and cytokine profiles were analyzed. Statistical analysis included comparison between OROV and DENV patients. RESULTS: Genome sequencing of OROV isolates confirmed presence of a previously reported novel reassortment event, consistent with ongoing localized transmission. Urine RT-PCR demonstrated low positivity compared to serum samples. The paired PRNT increased sensitivity in 45%. Clinically, OROV infection was associated with significantly higher frequencies of severe headache, myalgia, arthralgia, and rash compared to DENV infection (p&#x2009;<&#x2009;0.001). Elevated alanine aminotransferase (ALT) levels were also observed in OROV patients (p&#x2009;<&#x2009;0.001). Immunologically, OROV infection induced significantly increased levels of acute-phase CCL11 (eotaxin), CXCL10, IFN-&#x3b3;, IL-1RA, and IL-10, which declined by day 28, while IL-5 increased during recovery. In contrast, DENV patients exhibited elevated levels of CCL2, G-CSF, and CCL3 in recovery phase. CONCLUSION: OROV symptoms overlap with DENV underscores the need for syndromic diagnostic approach in endemic regions. Continued genomic surveillance and expanded clinical studies are vital to assess long-term consequences. Given OROV's expanding geographic range, targeted public health measures are essential to mitigate future outbreaks and better understand its pathophysiology.

Humans↗
PubMed1992

Arbovirus isolations from mosquitoes collected during 1988 in the Senegal River basin.

During August and September 1988, we collected adult mosquitoes from 14 locations in the Senegal River basin to search for evidence of Rift Valley fever (RVF) viral activity one year after the 1987 outbreak, which occurred along the Senegal-Mauritania border. More than 62,000 specimens representing 18 species in seven genera were collected with carbon dioxide-baited, solid-state Army miniature light traps and sheep-baited traps. Twenty virus isolations from Culex, Aedes, and Anopheles mosquitoes were recovered from six locations: Fanaye Diery (11), Bode (four), Matam (two), Diongui (one), Ndialene (one), and Ngoui (one). Species yielding viral isolates were Anopheles pharoensis (eight), Culex tritaeniorhynchus (three), Cx. univitattus gr. (three), Cx. antennatus (two), Cx. poicillipes (two), Ae. hirsutus (one), and An. gambiae (one). Viruses were identified by complement fixation, and virus and plaque-reduction neutralization testing as Ngari (Bunyavirus, Bunyaviridae) (n = 15), Babanki (Alphavirus, Togaviridae) (n = 3), Bagaza (Flavivirus, Flaviviridae) (n = 1), and Bangui (Bunyavirus-like) (n = 1). No evidence of any RVF viral activity in the Senegal River Basin was detected in the mosquitoes tested.

Animals↗