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PubMed1985

Comparison of dengue virus plaque reduction neutralization by macro and "semi-micro' methods in LLC-MK2 cells.

A simplified "semi-micro' plaque reduction neutralization test (PRNT) for dengue antibody in LLC-MK2 cells in disposable tissue culture plates is described. The assay compares favorably with the standard PRNT in glass prescription bottles, with relative sensitivity and specificity both 100% at a 1:40 screening dilution by 70% plaque reduction criteria. The assay is easy to perform, economical of time, expense, and storage space, and is suitable for study of sera available in small volumes, such as those obtained on filter paper or by the capillary method. The LLC-MK2 semi-micro PRNT is an acceptable alternative to the standard PRNT, particularly in laboratories that use these cells routinely for other tissue culture work and for flavivirus vaccine development.

Antibodies, Viral↗
PubMed1990

Isolation and characterization of attenuated plaque variants of infectious bursal disease virus.

Attenuated plaque variants were obtained from infectious bursal disease virus adapted to chick embryo cell cultures. The large plaque (Lp) clone and the small plaque (Sp) clone formed homogeneous plaques about 5 and 1 mm in diameter, respectively. Neutralization tests indicated that these clones differed little from their parent strain in antigenicity. Sp clones showed a retarded growth rate in chick embryo cell cultures as compared with Lp clones. The clones were significantly less pathogenic for chick embryos than the parent strain, although Lp clones were more pathogenic than Sp clones, and they were much less pathogenic for 1-day-old chicks and 28-day-old chickens. Both clones had immunizing potency in 28-day-old chickens, although the Lp clone had a somewhat higher potency than the Sp clone. These findings suggest the Lp and Sp clones, in particular the Lp clones, to be useful as live virus vaccine strains.

Animals↗
PubMed1992

Belgrade virus: a new hantavirus causing severe hemorrhagic fever with renal syndrome in Yugoslavia.

Two biologically and genetically distinct hantaviruses were isolated from blood and urine specimens collected from four Yugoslavian patients with clinically severe hemorrhagic fever with renal syndrome (HFRS). Viral isolates from three patients, designated strains Belgrade 1-3, were distinct from Hantaan, Seoul, Puumala, and Prospect Hill viruses as determined by plaque-reduction neutralization tests and restriction analysis of enzymatically amplified M-segment fragments. The fourth isolate, called Kraljevo, was indistinguishable from Hantaan virus. Strains Belgrade 1 and 2, like the Kraljevo strain, caused a fatal meningoencephalitis in newborn mice inoculated with 100 pfu of virus intracerebrally and intraperitoneally. Strain Belgrade 3 was much less neurovirulent, requiring 30,000 pfu of virus to cause fatal disease in mice. These data indicate that two distinct hantaviruses, one of which constitutes a new serotype, cause clinically severe HFRS in Yugoslavia.

Adult↗
PubMedDate not supplied

[Identification of a new antigenic variant of simian adenovirus (SV30N)].

A new variant of simian adenovirus SV30-N is described. The variant is antigenically close to SV30 virus in the neutralization test but has some antigenic relationship to SA7 virus. The properties of SV30-N virus were retained after 5 clonings by the plaque method, after passage and cloning of the virus treated with immune sera to SV30 or SA7. The heteroduplex analysis showed DNA of the virus under study to be by 80% and 40% homologous to SV30 DNA and SA7 DNA, respectively, whereas no heteroduplex molecules between SV30 and SA7 DNA were found. By the set of polypeptides the antigenic variant SV30-N is close to SV30 but differs from SV30 and, particularly from SA7. Unlike SV30 and SA7 viruses, the SV30-N virus showed no oncogenic activity for hamsters.

Adenoviridae↗
PubMed1983

Immunity to poliomyelitis in Sydney's children.

No indigenous cases of poliomyelitis have occurred in New South Wales since 1970, and it was presumed that herd immunity was high. However, our survey of Sydney's children by the neutralization test showed that only 42% of children had antibody levels (titre 8 or higher) to all three serotypes, 30% had antibodies to two, 16% to one, and 12% had no demonstrable antibodies at all. The immune status could not be determined with confidence from the immunization history, as 48% of the children who were reported as having received four or more doses of Sabin vaccine were not fully immune. When children who had inadequate levels of antibodies were given a single dose of Sabin vaccine, 77% of them achieved adequate antibody levels to all three viruses. The Health Commission of New South Wales subsequently undertook a mass Sabin immunization campaign of primary-school children, and reviewed the recommended immunization schedule.

Antibodies, Viral↗
PubMedDate not supplied

Serological survey of infectious bursal disease virus serotypes 1 and 2 in California turkeys.

The prevalence of two infectious bursal disease (IBD) viruses--serotype 1, of chicken origin, and serotype 2, of turkey origin--was studied in California turkeys. Serum samples were collected from 15 turkey flocks representing nine counties. The virus-neutralization test was used. Overall, only 15% of 342 samples were positive for serotype 1, whereas 89% were positive for serotype 2. However, 12 out of 15 flocks had a least one sample positive for serotype 1, and 14 out of 15 flocks had at least one sample positive for serotype 2. Flocks with antibodies to serotype 1 had low geometric mean titers (GMTs) (1.5 to 8.8) and low-to-medium prevalence rates (5 to 53.3%). Flocks with antibodies to serotype 2 had high GMTs (36.8 to 2048) and high prevalence rates (60 to 100%). Results of this study lead us to question the efficacy of IBD vaccination in turkeys.

Animals↗
PubMed1979

Antigenic analysis of acute hemorrhagic conjunctivitis viruses (enterovirus type 70).

The antigenic characteristics of enterovirus type 70 (EV 70) were investigated by means of cross and kinetic neutralization tests (NT). Twelve strains of EV 70 isolated in a period from 1971 to 1976 were analyzed using seven rabbit and one monkey hyper-immune sera. All the strains investigated were found to possess a common and prime variant antigens in varying proportions. Accordingly, EV 70 isolates were devided intratypically into three antigenic sub groups; (1) prototype-like (four strain from 1971 to 1972), (2) intermediate, G-10/72-like (two strains from 1972 to 1973), and (3) prime variant, G-2/74-like (six strains from 1974 to 1976) groups. Thus it was considered that EV 70 might represent a virus type with antigenic heterogeneity, and that antigenic drift from the prototype to the prime type may have occurred successively after 1971.

Antigens, Heterophile↗
PubMed1991

A serologic study of California serogroup bunyaviruses in Sri Lanka.

A seroepidemiologic study of California (CAL) serogroup viruses (genus bunyavirus, family Bunyaviridae) was carried out on 952 human and 1,834 animal sera collected from different ecological zones of Sri Lanka (latitudes 5-10 degrees N, longitudes 79-82 degrees E). The sera were screened for neutralizing antibody to Lumbo (LUM), snowshoe hare (SSH), and trivittatus (TVT) viruses by plaque neutralization tests on Vero cells. Of 2,786 sera screened, 262 (9.5%) had antibody to one or more viruses Twenty-two sera, selected to represent different species of origin and reaction profiles, were titrated against nine CAL viruses: LUM, SSH, TVT, Tahyna (TAH), California encephalitis (CE), La Crosse (LAC), Inkoo (INK), Melao (MEL), and Guaroa (GRO). Results suggested that there were multiple CAL viruses active in Sri Lanka, one or more of them closely related to LUMBO and SSH viruses, and another related to MELAO virus. These viruses were active in both the wet and dry zones of the country, and infected humans as well as a range of domestic livestock.

Adolescent↗
PubMed1993

Antigenic comparison of Ockelbo virus isolates from Sweden and Russia with Sindbis virus isolates from Europe, Africa, and Australia: further evidence for variation among alphaviruses.

The plaque-reduction neutralization test (PRNT) was used to compare 15 isolates of Ockelbo virus from Sweden, one isolate of Ockelbo virus from Russia, the Egyptian prototype Sindbis virus, and Sindbis-like viruses from Slovakia, South Africa, Cameroon, and Australia. Strains from northern Europe (Sweden and Russia) were indistinguishable by PRNT. We observed some antigenic variation between isolates of Sindbis virus from Europe, Africa, and Australia. An Australian strain (C-377) was shown to be distinct from prototype Sindbis virus, and the Acrocephalus strain from Slovakia was shown to be identical to prototype Sindbis virus. All other strains, including Ockelbo virus isolates, were shown to be subtypes of prototype Sindbis virus.

Alphavirus↗
PubMedDate not supplied

[Identification of a new antigenic variant of simian adenovirus SA7 P].

Serological, biological, and physico-chemical properties of a new antigenic variant of simian adenovirus SA7P were studied. Neutralization tests with hyperimmune specific antisera demonstrated the new antigenic variant SA7P to have very significant antigenic similarity with the prototype SA7 strain. Same as the latter, SA7P does not agglutinate rat red blood cells, is highly oncogenic for newborn Syrian hamsters and capable of transforming rat kidney cell cultures. At the same time, the method of heteroduplex analysis showed SA7P DNA to be homologous to DNA of the reference SA7 strain by 85% and to contain 3 non-homologous regions in the right part of the virus genome. Comparison of the physical maps of the 2 virus DNAs by 4 restrictases established considerable differences in the number of recognition sites and their location.

Adenoviridae↗
PubMed1997

A serological survey of bovine herpesvirus-1 infection in selected dairy herds in northern and central Italy.

Serum samples from a total of 6979 dairy cattle from 55 herds in northern Italy (51 herds) and central Italy (4 herds), were examined by the serum neutralization test for the presence of antibody to bovine herpesvirus-1 (BHV-1). It was found that 84.31% of the farms selected in northern Italy and all the farms from central Italy had seropositive animals at titers of 1:4 or higher. The prevalence of infection was essentially the same among the cattle populations of the two selected areas of the country, being of 34.99% in the north and of 38.65% in central regions. A comparison of the data from the present study with those obtained in a serological survey conducted in Italy in 1966, shows that the rate of seropositive cattle to BHV-1 has increased by about 5.0% in the last 30 years.

Animals↗
PubMedDate not supplied

[Virological and serological characteristics of outbreaks and sporadic cases of acute gastroenteritis].

Specimens from patients with gastroenteritis (GE) collected during outbreaks and from sporadic cases reported in the USSR in 1979-1984 were examined by electron microscopy (EM), enzyme immunoassay, rotavirus neutralization test in cell culture. All the winter-spring outbreaks and a considerable number (34.9%) of sporadic GE cases were caused by rotaviruses. The summer-autumn outbreaks were of non-rotavirus nature. In water-borne winter-spring outbreaks in adults, severe forms of GE with signs of dehydration were observed. Among infants, cases of virus-carrier state were detected. The rate of rotavirus detection by EM in winter-spring outbreaks depended on the time of specimen collection and decreased after 4 days from the onset of the disease. Apart from rotaviruses, adeno-, astro-, calici-, coronaviruses, and picornavirus-like particles were detected by EM in feces from GE patients.

Acute Disease↗
PubMed1989

Immune response of the llama (Lama glama) to tetanus toxoid vaccination.

An ELISA was developed to measure serum concentrations of tetanus toxoid-specific immunoglobulins. The titers obtained with this assay were compatible with those obtained by the standard mouse toxin-neutralization test. Serum samples from 123 llamas were analyzed for ELISA titers to tetanus toxoid. Of the 82 vaccinated adults, 75 (91%) had titers greater than or equal to 1:50. The vaccination status and titers of weanlings and juveniles (3 to 12 months old) varied; of the 21 vaccinated, 17 (81%) had titers greater than or equal to 1:50 and 7 of 9 (78%) unvaccinated llamas had titers less than 1:50. The ELISA titers of unvaccinated llamas less than 8 weeks old (crias) were matched with the maternal titers. All crias with titers less than 1:50 had dams with titers greater than or equal to 1:50.

Animals↗
PubMed2006

A recombinant fusion protein containing the domain III of the dengue-2 envelope protein is immunogenic and protective in nonhuman primates.

We have previously reported the construction and evaluation in mice of recombinant fusion proteins formed by a fragment (aa 286-426) of the dengue envelope protein and the P64k protein from Neisseria meningitidis. In this work we describe the immunization of Macaca fascicularis monkeys with two variants of these proteins [PD3 (insertion variant) and PD5 (fusion variant)] corresponding to serotype 2. Four doses of the proteins adjuvated in Freund's adjuvant were administered and the kinetics of antibody induction was monitored by ELISA and neutralization tests. Monkeys receiving PD3 or PD5 developed functional antibodies (Abs) in a dose-dependent manner. Following challenge with 5 log PFU of wild type dengue-2 virus (DEN2), animals immunized with PD5 were protected from developing viremia. These results constitute a proof-of-concept demonstrating that a fragment of the dengue envelope protein, containing the domain III and produced as a recombinant fusion protein in Escherichia coli, induces functional and protective immunity in a nonhuman primate model.

Adjuvants, Immunologic↗
PubMedDate not supplied

[Detection of antiviral activity of monoclonal antibodies, specific to Marburg virus proteins].

Monoclonal antibodies (MAbs) specific to Marburg virus (MBG), Popp strain, have been previously produced and characterized by indirect ELISA. Protein specificity of MAbs was determined by immunoblotting with SDS-PAGE proteins of MBG: one to NP, four to VP40, and protein specificity of one antibody was not detected. The effect of MAb binding to protein epitopes on viral functions was investigated in vitro and in vivo. None of antibodies neutralized the virus in the neutralization test in vitro, but MAb 5G9.G11 and 5G8.H5 specific to MBG VP40 protein were active in antibody-dependent complement mediated lysis of virus-infected cells. In vivo these antibodies (5G9.G11 and 5G8.H5) protected guinea pigs from lethal MBG infection after passive inoculation. Studies of biological activity and analysis of epitope specificity of MAb-antiVP40 by competitive ELISA showed that 2 of 7 epitopes of VP40 protein of MBG induce the production of protective antibodies. Hence, MAbs 5G9.G11 and 5G8.H5 reacting with MBG VP40 protein caused lysis of virus infected cells in the presence of the complement in vitro and protected guinea pigs from MBG infection by passive inoculation.

Animals↗
PubMed1997

Protective vaccination of ferrets against canine distemper with recombinant pox virus vaccines expressing the H or F genes of rinderpest virus.

OBJECTIVE: To investigate the ability of rinderpest virus (RPV) antigens, expressed in pox virus vectors, to protect against canine distemper virus (CDV) infection in ferrets. ANIMALS: Ferrets (Mustela putorius; n = 27) with no previous exposure to CDV. PROCEDURE: Ferrets were inoculated intradermally with recombinant vaccinia viruses expressing the H gene of RPV, the F gene of RPV, the H and F genes of RPV, or fowlpox virus recombinant expressing both genes. Two ferrets were vaccinated s.c. with CDV vaccine as positive controls, and 1 group was left unvaccinated as a negative control. Blood was obtained from ferrets biweekly; antibody titer to RPV was detected by ELISA, and CDV antibody titer was measured by serum neutralization testing and ELISA. RESULTS: Partial protection was seen in all groups, with vRVFH vaccination being the most protective (60%). CONCLUSIONS AND CLINICAL RELEVANCE: A single inoculation with a vaccinia virus expressing the H and F genes of RPV was able to protect 60% of the vaccinated ferrets challenge exposed with a high dose of CDV. These results indicate the ability of RPV antigens expressed by vaccinia virus to protect ferrets against a related morbillivirus. Further, they document the safety and efficacy of a recombinant vaccinia virus vaccine for ferrets. Such vaccines may be useful given the susceptibility of ferrets to CDV and the problem of maternal antibody interfering with vaccination of young animals.

Animals↗
PubMed2005

Isolation of equine herpesvirus-2 from the lung of an aborted fetus.

This study describes the isolation of equine herpesvirus-2 (EHV-2) from the lung of an aborted equine fetus in Argentina. The isolated virus was confirmed as EHV-2 by indirect immunofluorescence using a rabbit anti-EHV-2 polyclonal antiserum and by virus-neutralization test using an equine polyclonal antibody against EHV-2. Restriction endonuclease DNA fingerprinting with BamHI also confirmed the identity of the virus as EHV-2. Furthermore, viral nucleic acid was detected by polymerase chain reaction from the original lung sample and from the DNA obtained from cells infected with the virus isolate. This work constitutes the first reported isolation of EHV-2 from an aborted equine fetus. The presence of EHV-2 in the lung of the aborted fetus would indicate that this virus is capable of crossing the placental barrier. However, no cause-effect relationship was established between the EHV-2 isolate and the abortion.

Aborted Fetus↗
PubMed2006

West Nile virus in Guadeloupe: introduction, spread, and decrease in circulation level: 2002-2005.

In July 2002, a surveillance system was implemented on Guadeloupe to detect for the potential introduction and monitor the spread of West Nile virus (WNV). From 2002 to 2004, equines and chickens were serologically assayed for antibodies to WNV by IgG and IgM enzyme-linked immunosorbent assay (ELISA), epitope-blocking ELISA, and plaque reduction neutralization tests. After introduction, probably through migratory birds at the end of 2001, many seroconversions occurred between July and October 2002 resulting in a high seroprevalence (19.3%) in equines in 2003. WNV circulation levels decreased dramatically in 2003 and 2004 as assessed by the absence of seroconversion in equine and the very low prevalence in chickens. This decrease coincided with a 7-month drought that presumably caused a decrease in vector populations. In 2005, a sentinel survey was implemented in equines and chickens placed in areas at high risk and the very low rate of seroconversion (1 equine out of 106, no chicken) demonstrated that WNV circulation is now occurring at a very low level.

Age Factors↗