Showing papers on "Dengue virus published in 1975"

A lipid inhibitor of dengue virus in human colostrum and milk; with a note on the absence of anti-dengue secretory antibody

Abstract: Neutralizing activity against dengue virus types 1--4 was observed in milk samples from 5 non-immune and 29 dengue immune women. Anti-dengue activity in milk and colostrum was found only in the lipid component. The inhibitory activity is directed against the virus and not cell surfaces. When immunoglobulin types IgM,IgA, IgG were isolated from colostrum from dengue immune women, no antibody activity was found. Anti-dengue activity in human milk did not decrease over a period of ten months after delivery.

Placental Passage of Antibodies to Dengue Virus in Persons Living in a Region of Hyperendemic Dengue Virus Infection

Abstract: Maternal and umbilical cord levels of antibodies to dengue 2 and 3 viruses were compared in 54 matched pairs of specimens from subjects in the Dominican Republic. Dengue infection appeared to be hyperendemic; pregnant women experienced a 6% weekly infection rate. Titers of antibody to dengue 2 and 3 viruses were considerably higher in cord sera than in maternal sera (P smaller than 0.001 and P smaller 0.01, respectively), especially when maternal levels were low. When maternal and cord sera were compared at equal titers of dengue 2 virus, heterotypic antibodies to dengue 1 and St. Louis encephalitis viruses were higher in the cord. These findings could not be directly related to the higher levels of IgG found in cord sera or to the presence of elevated concentrations of IgM. It is concluded that antibody with increased cross-reactivity preferentially crosses the placenta. The presence of such cross-reactive antibody does not appear to sensitize infants to dengue hemorrhagic fever/shock syndrome.

Dengue carrier culture and antigen production in human lymphoblastoid lines.

Abstract: Replication of dengue type 2 (D2) viruses was studied in four lymphoblastoid cell lines; Raji, HRi, EB3 and RPMI 6410. The HRi cell line failed to support D2 growth while the other cell lin

Arbovirus infections in Sarawak, October 1968–February 1970: Human serological studies in a Land Dyak Village

Abstract: 449 human sera collected in a Land Dyak village were tested for antibodies to 11 arboviruses. Japanese encephalitis and dengue virus antibodies were particularly prevalent. The rates of infection with these viruses were estimated to be 5-2% per annum for Japanese encephalitis, 8-8% for dengue 1 and 4-3% for dengue 2. Chikungunya virus antibodies were quite common with an annual infection rate of the order of 5% per annum. Infections with other Group A and B and Bunyamwera group viruses were generally at a low level.

The effect of dengue virus infection on the clinical sequelae of Japanese encephalitis: a one year follow-up study in Thailand.

Abstract: In order to determine if prior dengue virus infection reduces the severity of Japanese encephalitis (JE), we examined 127 patients hospitalized during the 1970 JE epidemic in the Chiangmai and Lampang Valleys of northern Thailand. Patients were studied during the first 30 days after onset of JE; 120 of these patients were examined one year later for residual neurologic sequelae. About 21% of patients had serological evidence of a prior dengue virus infection. Morbidity and mortality in patients with and without prior dengue virus experience were compared. These comparisons were made within two age groups to exclude differences due to age alone;

Dengue Virus Plaque Formation on Microplate Cultures and Its Application to Virus Neutralization

Abstract: Discussion and SummaryDengue virus plaque formation on BHK-21 cell micro-plate cultures was described. The clear plaques were visible usually 5 days after incubation in a CO2 incubator at 37°. The cells cultured in a 3-oz bottle were sufficient to prepare two microculture plates which were usually ready for use after 1-2 days of cultivation in the CO2 incubator at 37°. The overall procedures were easy and of economic advantage.It is to be stated in this connection that the affinity of dengue viruses to tissue culture cells is not necessarily high, so that the cell culture systems suitable for dengue virus plaquing have so far been limited; and even in such suitable systems the formation of clear plaques takes a much longer time of incubation than for other kinds of arbo-viruses in general. Some of the difficulties regarding this matter have been overcome by the techniques reported here.By use of the microplate cultures, in combination with the transfer-plates reported by previous investigators (8), dengue...

Indirect fluorescent antibody technic for demonstration of serum antibody in dengue hemorrhagic fever cases.

Abstract: One hundred eighty-three sera from two groups of children with dengue hemorrhagic fever and 37 control sera were examined for antibody against dengue virus by an indirect immunofluorescent method. When the reciprocal titer of 16 or higher was used as the diagnostic level, positive tests could be obtained in 80% of Group I and 100% of Group II sera after 3--6 days of fever. Positive tests were obtained in 100% of both groups after the first week of fever. There was no false-positive among the control sera. Preparation of the antigen is relatively easy, and the antigen may be stored for at least 3 months. The immunofluorescent method is rapid and simple, and is recommended for routine detection of serum antibody in dengue hemorrhagic fever.

Influence of cell type and virus upon virus-specific immune cytolysis.

Abstract: Immune cytolysis was measured by release of absorbed radioactive chromium from infected cells that were incubated with antiviral antibody and complement. The presence of virus-specific antigens detected in this manner on the surface of several types of cells infected with Japanese encephalitis (JE) virus did not correlate in each instance with the maturation of infectious virus. JE-infected LLC-MK-2 and Vero cells could not be lysed until long after the first appearance of released virus, and the lysis was minimal in that only a small amount of chromium was released. However, JE-infected BHK-21 and chicken embryo cells could be lysed as soon as new virus was detected in the culture medium, and the lysis reached maximum levels before the time that maximum levels of infectious virus were found in the culture fluids. This phenomenon was restricted to JE virus since BHK-21 cells infected with dengue-2 virus (another group B arbovirus) could not be lysed until well after the appearance of new virus in the culture medium.

Sensitivity of rapid plaque assay method of dengue viruses.

Abstract: The sensitivity of the hemadsorption-negative plaque test for the infectivity assay of dengue virus type 2 was compared with those of other methods such as conventional plaque test, intracranial inoculation technique of suckling or weanling mice and intrathoracical inocu- lation technique of Aedes aegypti. The results indicated that the infectivity of the virus can be rapidly and reliably assayed by this method and the sensitivity of the method is higher than that of suckling or weanling mice intracranial inoculation technique, although about 5-fold less sensitive than that of intrathoracical inoculation technique of Aedes aegypti. Physicochemical, biochemical and growth characteristices of mouse brain passaged dengue viruses have been extensively studied. However, many problems still remain un- clear, especially on the pathogenicity of the virus and the pathogenesis of dengue hemorrha- gic fever. One of the main reasons of the slow progress in these fields might be due to the lack of adequate virus growth system and rapid assay method of the infectivity of the virus in tissue culture. Various assay methods of the virus in tissue culture system have been repor- ted (1, 2, 3, 4, 6, 12, 14, 16) previously, but they, in general, take long incubation peri- ods to obtain the results and are less susceptible than 2 to 3-day-old suckling mouse intra- cranial inoculation method.

Dengue virus replication in cultures of peripheral blood leukocytes during the course of dengue haemorrhagic fever.

Abstract: A preliminary study was made of the ability of cultured human peripheral blood leukocytes (PBL) to support dengue 2 infection. Leukocyte donors, children hospitalized with primary (one case) or secondary dengue infections (12 cases), were studied during the acute and convalescent stages of illness. D2 virus replication occurred infrequently in PBL cultures obtained from children before the 10th day after onset of symptoms (2/23 samples), but frequently thereafter (8/13 samples). The absence of virus permissive cells during the acute stage of illness might be explained by several different mechanisms, including the possibility that permissive PBL are exhausted as the result of a severe dengue infection. An unexpected finding was the appearance of dengue hemagglutination-inhibition antibodies in cultures of PBL obtained from children during the acute stage of secondary dengue infections.

The influence of arboviral infection on the susceptibility of cultured cells to immune injury in vitro.

Abstract: The susceptibility of LLC-MK2 monkey kidney cells to antivirus (antibodies versus viral antigens in the plasma membrane) and anticell (antibodies versus plasma membrane antigens) immune cytolysis in vitro was observed during the course of 100 continuous subcultures of these cells. In that period, LLC-MK2 cells infected with the Group B arboviruses, Japanese encephalitis virus and dengue 2 virus, became progressively refractory to the complement-dependent antivirus immune cytolysis as measured by 51-Cr release. In addition, the LLC-MK2 cells themselves exhibited a decreasing susceptibility to immune lysis with anticell anti-body. In contrast, during the same period, similar immune cytolysis experiments with the Group A arboviruses, Sindbis virus and Eastern equine encephalitis virus, remained constant. It was observed that arboviral infection of lytic refractory LLC-MK2 cells restored their susceptability to immune cytolysis with anticell antibodies. The kinetics of this restoration were unique for both Group A and B arboviruses and exhibited a constant relationship to the viral growth curve. It was concluded that the above findings could be explained on the basis of differential membrane antigenic density coupled with changes in the properties of the plasma membrane on which subculture and arboviral infection had antagonistic effects.