Dengue infections in the Philippines: clinical and virological findings in 517 hospitalized patients

From May 1983 to January 1984, 517 patients with laboratory confirmed dengue were studied at a hospital in Manila. Secondary dengue infections were diagnosed in 78% of these cases. Peak admission (28%) occurred towards the end of the rainy season in November. Most patients (78%) were less than 15 years old but only 3 were infants. Although some type of hemorrhagic finding occurred in 460 cases (89%), only 110 were classified as dengue hemorrhagic fever and the remainder as dengue fever with hemorrhagic manifestations. The clinical course was usually mild. Gastrointestinal bleeding was present in 65 cases, but only 2 patients developed shock. No fatalities occurred. Dengue 2 was the predominant serotype with 53 isolates, followed by dengue 1 with 48 isolates, dengue 3 with 39 isolates, and dengue 4 with only 8 isolates. Dengue 2 was the only serotype with more isolates from sera with a homologous HI antibody titer greater than 1:20 (57%) than from sera with a homologous HI titer less than or equal to 1:20 (43%). In contrast, most of the dengue 1 isolates (63%) were from sera with a homologous HI antibody titer less than 1:10, and this serotype was strongly associated with primary infections. This study shows that dengue infections remain an important cause of pediatric hospitalization in the Philippines; however, the occurrence of life-threatening dengue hemorrhagic fever as has been described in several other large urban areas of Southeast Asia appears to be rare.     

Evidence of immunity induced by naturally acquired rotavirus and Norwalk virus infection on two remote Panamanian islands

For better understanding of the role of humoral immunity in ameliorating infections with rotavirus (RV) and Norwalk virus (NW), 305 Cuna Indians living on two isolated islands located off Panama's Carribean coast were surveyed daily for diarrhea over a seven-month period. Nine (8%) of 108 persons with a baseline RV antibody titer of greater than 1:4 developed RV infection compared with 70 (46%) of 151 persons with a baseline RV antibody titer of less than 1:4 (P less than .001). Thirty-eight (25%) of 151 persons of all ages with baseline RV antibody titer of less than 1:4 had at least one episode of RV diarrhea compared with 6 (6%) of 108 persons who had baseline RV antibody titers of greater than 1:4 (P less than .001). Thirty-two (47%) of 68 persons of all ages who had a baseline NW antibody titer of less than 1:100 developed NW infection compared with 30 (13%) of 237 persons with a baseline NW titer of greater than 1:100 (P less than .001). The high NW and RV infection rates and the excellent levels of protection provided by specific preexisting humoral antibody to these agents should promote activities aimed at developing vaccines for preventing these infections.     

The immune response in primary asymptomatic and symptomatic rotavirus infection in newborn infants

Systemic and mucosal immune responses were determined using an enzyme-linked immunosorbent assay in 18 infants (7-86 days old) experiencing primary rotavirus infections over two winters. Fifteen infected infants were asymptomatic; 3 had diarrhea. Neutralization antibody (NA) was assayed in two asymptomatic infants who had a serotype 1 isolate identified. Seven asymptomatic infants had sera available for analysis; none had IgG, 1 had IgM, but 4 had IgA antibody responses. Neither tested infant had a serotype 1 NA rise. In the 3 symptomatic infants, 1 had IgG, 2 had IgM, and all had IgA serum antibody responses detected. Eleven (73%) of 15 asymptomatic and all symptomatic infants had a rotavirus-specific fecal antibody response. These findings identify IgA as an important antibody in primary rotavirus infection in very young infants. The predominance of this antibody in asymptomatic infants suggests that their responses (and protection on subsequent reexposure) may be primarily mucosal.     

COXSACKIE B VIRUS ANTIBODY RESPONSES IN JUVENILE-ONSET DIABETES MELLITUS

A prospective serological study of patients with recently diagnosed juvenileonset diabetes mellitus was carried out to determine neutralizing antibody responses to Coxsackie B viruses. The sera were tested with and without staphylococcal protein A absorption, to selectively ascertain whether specific IgM or IgG antibody predominated. Of eleven patients studied, ten had reciprocal antibody titres of sixteen or greater to at least one serotype. Three patients showed no reduction in titre in at least one serum sample after protein A absorption, suggesting a predominant IgM-specific primary response to a recent infection by a Coxsackie B virus. The findings support the possibility that at least some cases of juvenile-onset diabetes mellitus are closely related to Coxsackie B virus infections.     

Diagnostics of Pogosta disease: antigenic properties and evaluation of Sindbis virus IgM and IgG enzyme immunoassays

Sindbis virus (SINV) is a mosquito-borne causative agent of a fever-rash arthritis, Pogosta disease, as verified recently by virus isolation from acutely ill patients. Pogosta disease occurs annually, but it emerges as unique epidemics every 7 years in Finland; over 10,000 patient samples have been analyzed for SINV antibodies, with over 2000 diagnosed acute SINV infections. However, the performance of these serological tests with a large number of samples has not been described before. The aim of the present study was to characterize and evaluate methods developed for the serodiagnostics of SINV infection, suitable for large sample numbers, and to examine the protein-specific responses to the antigen used. We developed SINV IgM and IgG enzyme immunoassays (EIA) using highly purified SINV. The EIAs were compared to hemagglutination inhibition (HI) and neutralization tests. We studied paired samples from 46 acutely ill patients taken at approximately 2-week intervals, with a verified SINV infection confirmed by a fourfold rise in HI antibody titer. The assay cut-off values and specificity were determined with confirmed negative sera. Protein-specific antibody responses were examined with immunoblot assay. The optical density values of the EIAs correlated well with the HI titers. The sensitivities of the IgM and IgG EIAs were 97.6% and 100%, and specificities were 95.2% and 97.6%, respectively. We consider that a verified serological diagnosis of acute SINV infection requires (1) in addition to a positive IgM result at least a fourfold increase in HI (or IgG) titer between paired sera or (2) a positive IgM result and a negative/borderline IgG result (which excludes old immunity) and specific reaction in HI. Both E1 and E2 glycoproteins of SINV were shown to be recognized by IgM and IgG antibodies early in infection.     

Serotype-Specific Host Responses in Rhesus Macaques after Primary Dengue Challenge

Dengue virus (DENV) is considered to be the most important arthropod-borne viral disease and causes more than 100 million human infections annually. To further characterize primary DENV infection in vivo, rhesus macaques were infected with DENV-1, DENV-2, DENV-3, or DENV-4 and clinical parameters, as well as specificity and longevity of serologic responses, were assessed. Overt clinical symptoms were not present after infection. However, abnormalities in blood biochemical parameters consistent with heart, kidney, and liver damage were observed, and changes in plasma fibrinogen, D-dimers, and protein C indicated systemic activation of the blood coagulation pathway. Significant homotypic and heterotypic serum immunoglobulins were present in all animals, and IgG persisted for at least 390 days. Serum neutralizing antibody responses were highly serotype specific by day 120. However, some heterotypic neutralizing activity was noted in infected animals. Identification of serotype-specific host responses may help elucidate mechanisms that mediate severe DENV disease after reinfection.     

Original antigenic sin in dengue

Sequential blood samples were obtained from eight Thai children before, during and 3-5 months after hospitalization for dengue shock syndrome. All patients experienced a secondary-type antibody response as evidenced by hemagglutination-inhibition antibody responses in acute and convalescent sera. Dengue 2 viruses were recovered from two patients. In their pre-illness blood sample, all children had monotypic neutralizing antibodies; five to dengue 1, two to dengue 3 and one to dengue 4. The highest neutralizing antibody titers in acute phase and late convalescent sera were to the initial infecting virus type. This report documents for sequential dengue infections the existence of an original antigenic sin antibody response. It may be possible to apply this phenomenon to identify initial dengue serotype infection in individuals experiencing secondary dengue infections, thus helping to clarify the antecedents to dengue shock syndrome.     

上海地区婴幼儿院内感染轮状病毒致腹泻病的分子流行病学调查

目的 了解上海地区婴幼儿院内感染轮状病毒(RV)致腹泻病的分子流行病学特征.方法 采用胶体金法和套式PCR,对2006年11月至2008年1月复旦大学附属儿科医院收集的226例院内感染性腹泻患儿的粪便标本进行RV病原检测,并对阳性标本进行分型,调查患儿的临床特征.数据分析分别以构成比、阳性榆出率表示,均值采用t检验.结果 胶体会法RV阳性率为47.8%.院内感染RV腹泻以1岁以内的年龄段最高,新生儿占RV腹泻患儿的32.4%.发病高峰在10、11月份.采用套式-PCR对除新生儿外的67份RV阳性标本进行分型,G3为主要流行的血清型,占46.3%,其次为G1占23.9%、G2占3.0%、G9占1.5%,7份为混合感染,均为G1、G3混合,10份未能分型.从P分型来看,主要流行株为P[8]型,占90.0%,其次为P[4]型占6.0%,3份标本未能分型.未发现P[6]、PE9]和P[10]型.G3P[8]为主要分离株,占61.2%,其次为G1P[8],占17.9%,G1、G3P[8]混合感染占9.5%,G2P[4]、G8P[9]各1例.新生儿32份RV阳件标本中10份成功分型,均为G1P[8].院内感染RV腹泻延长住院天数、增加住院费用.结论 RV是上海地区院内感染性腹泻病的主要病原,其流行的主要血清型为G3P[8]型,但仍需加强监测G1流行株的暴发流行.     

Immunodiffusion and agglutination tests for Candida in patients with neoplastic disease: inconsistent correlation of results with invasive infections.

A serological study of candidiasis was conducted with use of (1) sera sent to the laboratory by clinicians who suspected infections due to various organisms including Candida species, and (2) sera available in our serum bank from patients with candidiasis proven at autopsy and from those with documented candidemia. With this population of patients, we were able to evaluate both potential false-negative and false-positive results. Microimmunodiffusion and slide agglutination tests were used. In many cases, serial specimens were available for measurement of rises or falls in titers of agglutinating antibody. Sera from less than one-half of the patients with disseminated or invasive gastrointestinal candidiasis exhibited positive immunodiffusion reactions, titers of agglutinating antibody of greater than 1:16, or fourfold rises in titer of agglutinins. Sera from several patients with pharyngitis due to Candida and from several who were only colonized with Candida or for whom clinical or cultural evidence of candidiasis was lacking showed positive immunodiffusion reactions or agglutinin titers of greater than 1:16, and some showed fourfold rises in titer. Conversions from negative to positive immunodiffusion reactions were not consistently correlated with invasive candida infection. Using the methods described, we have not found immunodiffusion tests and titers of agglutinating antibody to be reliable indicators of invasive candida infection, since false-positive as well as false-negative reactions occur. Greater specificity for invasiveness as well as greater sensitivity in immunosuppressed patients are necessary before these tests can become important adjuncts to the evaluation of patients with suspected invasive candidiasis.     

Isolation of dengue viruses from hospitalized patients in the Philippines, 1983-1986

Between 1983-1986, 336 strains of dengue virus were isolated from 1,911 patients who had been hospitalized with clinically suspected DF/DHF in Manila and nearby areas. Multiple serotypes were present every year. Although DEN 3 was the most common serotype isolated (40%) over the entire study period, DEN 2 and DEN 1 were more frequently isolated in 1983 and 1984, respectively. DEN 4 was consistently the least common serotype recovered. During 1984, geographic differences in the pattern of serotypes isolated were found for two heavily populated areas located only 70 km apart. A higher proportion of DEN 2 isolates were recovered from patients with gastrointestinal bleeding compared to DEN 1 and DEN 3. A higher proportion of DEN 1 and DEN 3 isolates came from patients experiencing a 1 degree infection compared to DEN 2, and the mean homologous HI antibody titer of the sera that DEN 2 was isolated from was significantly higher than the homologous titers of sera from which DEN 1 and DEN 3 were isolated.     

Immunoglobulin Classes of Antibody for Human T-Lymphotropic Virus Type-I (HTLV-I) in Healthy Donors and HTLV-I-Associated Disorders

Healthy blood donors, patients with adult T-cell leukemia (ATL) and HTLV-I-associated myelopathy (HAM) and recipients of unscreened blood (SR) who had seroconverted and were followed-up for more than 2 years were examined for HTLV-I antibodies of immunoglobulin G (IgG) and M(IgM) classes. The overall infection rate in donors was 4.9%, as determined by screening with a particle agglutination method (PA). The rate increased with increasing age. Positive sera with a low titer in the PA test (1/16, 1/32 and 1/64) contained IgM antibodies in 32.5% (titer 1/16) to 36.1% (titer 1/64) of the cases, but IgG antibodies were detected in only 5.6% of the sera with a titer of 1/16 and in 36.1% of the sera with a titer of 1/64. Conversely, in high titer sera (1/128 or higher) IgG antibodies were almost always detectable (99.0%) and IgM antibodies less frequently (25.5%). Sera from acute, chronic and pre-ATL, HAM and SR patients contained IgG antibodies in high titer in all cases. The incidence of IgM antibodies was 7.7, 30.0, 53.3, 72.3, and 77.8%, respectively. IgM antibodies were demonstrated repeatedly in some cases who were followed up for a year. Only IgM antibodies from HAM patients occurred in high titers and had strong reactivity to the p24 antigens of HTLV-I in Western blot testing. It is concluded that it is important to detect IgM antibodies not only in primary infections but also in persistent infections of HTLV-I.     

Maternal antibody-mediated protection against gastroenteritis due to rotavirus in newborn mice is dependent on both serotype and titer of antibody

In order to evaluate the role of passively acquired, rotavirus-specific antibodies in protection against diarrhea, we inoculated mouse dams with rotaviruses of various serotypes, and their newborns were orally challenged with a primate rotavirus (simian SA-11). Dams were immunized by using a regimen that included repeated inoculations administered either orally or intraperitoneally with adjuvant. The serum antibody response detected in dams by radioimmunoassay and plaque-reduction neutralization after parenteral immunization was approximately 15-fold and 80-fold greater, respectively, than that found after oral "hyperimmunization." Parenteral immunization with rotavirus serotypes either homotypic or heterotypic to the challenge virus protected suckling mice against diarrhea; protection was closely correlated with the in vitro neutralizing activity of maternal serum against the challenge virus. Oral immunization with only rotavirus strains homotypic to the challenge virus afforded protection; the lower immune response after oral immunization with rotaviruses heterotypic to the challenge virus resulted in a titer of neutralizing antibody to the challenge virus below the protective threshold. From our current studies it appears that antibody-mediated passive protection against rotavirus challenge is dependent on both serotype and titer of antibody.     

Differential antibody responses to rubella virus infection in males and females.

Specificities of human rubella virus (RV)-specific IgG, IgM, and IgA antibodies for RV structural proteins (envelope E1 and E2 and capsid) and an E1 domain represented by a synthetic peptide (BCH-178) were determined by immunoblot and ELISA techniques in sera from rubella-infected individuals. Sequential sera were obtained from 67 females and 32 males during acute and convalescent infection phases. Males and females had differences in all antibody classes, especially during the early acute infection phase. At no time during follow-up were IgA anti-E2 antibodies detected in males, in contrast to the case in females. Significantly lower levels of IgG antibody directed to E2 were also observed in males. Males had earlier onset of E1-specific IgG and IgM antibodies with a greater proportion of total RV antibody response directed to E1 (IgG) or E1 peptide (IgM). These differences suggest there are hormonal and genetic influences on immune recognition of RV proteins that may be related to the increased incidence of rubella-associated arthropathy in females.     

Frequency of seroreactors to Legionella among the patients with pulmonary infections

A prospective study was conducted with patients with pulmonary infections who were consecutively admitted to the three community hospitals in Benghu from July 1986 to May 1987, and to the children's hospital in Nanjing from September 1986 to January 1987. Antibodies to Lpi-8, Lm, Ld, and Lg were measured by the micro-agglutination test. During the study period, 150 adult patients (100 pairs sera) and 212 control healthy people and 110 pairs sera of childhood patients and 173 children without respiratory tract infections were investigated. The diagnosis of legionellosis was based on seroconversion (fourfold rise in titer to greater than 1:32 or static titer of greater than 1:32) and clinical and radiographic features of legionnaires' disease. About 11% legionella infection in hospitalized adult patients with pulmonary infections, and about 5.45% in children with atypical pneumonias.     

Neutralization of Dengue Virus Serotypes by Sera from Dengue-Infected Individuals Is Preferentially Directed to Heterologous Serotypes and Not against the Autologous Serotype Present in Acute Infection

Sequential infections of humans by the four different dengue serotypes (DENV-1–4) lead to neutralizing antibodies with group, cross, and type specificity. Virus neutralization of serotypes showed monotypic but mostly multitypic neutralization profiles due to multiple virus exposures. We have studied neutralization to heterologous, reference DENV serotypes using paired sera collected between days 6 and 37 after onset of fever. The DENV-primed neutralization profile of the first serum sample, which was monitored by a foci reduction neutralization test (FRNT), was boosted but the neutralization profile stayed unchanged in the second serum sample. In 45 of 47 paired serum samples, the predominant neutralization was directed against DENV serotypes distinct from the infecting serotype. Homologous neutralization studies using sera and viruses from the same area, 33 secondary sera from DENV-1 infected Cambodian patients and eight virus isolates from Cambodia, showed that the FRNT assay accurately predicted the lack of a predominant antibody response against the infecting DENV-1 serotype in contrast to FRNT results using the WHO set of DENV viruses. This report provides evidence that DENV-primed multitypic neutralizing antibody profiles were mainly boosted and stayed unchanged after secondary infection and that DENV neutralization was predominantly directed to heterologous DENV but not against the infecting homologous serotype.     

Virus-specific IgG and IgM antibodies in normal and immunocompromised subjects infected with cytomegalovirus

Levels of IgG and IgM antibodies t human cytomegalovirus (CMV) were measured using a solid-phase radioimmunoassay. Individuals positive by complement-fixation test consistently had detectable IgG titers by radioimmunoassay, but no quantitative relationship was apparent. An elevated IgM titer was considered specific for CMV infection because sera from individuals with other herpesvirus infections did not cross-react. In patients with mononucleosis, elevated titers of IgM antibody to CMV correlated (P less than 0.001) with active infection and were highest during viremia. Titers of IgG antibody to CMV during and after symptomatic infection were similar to those of asymptomatic positive individuals. Increases in CMV-specific IGM were observed in both primary and reactivated infections in cardiac transplant recipients. In a small group of cardiac transplant recipients with recurrent symptomatic disease, IgM titers were low at the time of viruria and did not increase with CMV tissue involvement, a result which suggests that quantitative deficiencies in IgM may be related to the severity of CMV infections.     

Homotypic and heterotypic epitope-specific antibody responses in adult and infant rotavirus vaccinees: implications for vaccine development

Sera from infants and adults who received a live, attenuated monovalent rotavirus vaccine of serotype 1, 2, 3, or 4 VP7 specificity and rhesus rotavirus (RRV) VP4 specificity were analyzed for serotype-specific antibody responses by an epitope blocking immunoassay (EBA) and by neutralization. Although the assays correlated well, responses to the individual neutralization proteins or to different defined antigenic sites on the same protein could be distinguished only by EBA. In general, adult vaccinees exhibited both a homotypic response to the immunizing strain and a heterotypic response to other serotypes. Infant vaccinees less than 6 months old also had a homotypic antibody response but developed significantly fewer heterotypic responses than adults (1.2% and 59%, respectively; P less than .0001). In addition, postvaccination sera from vaccinees who developed naturally occurring rotavirus diarrhea during an efficacy trial of RRV (MMU-18006) or RIT 4237 vaccine were analyzed for serotype-specific responses. The data suggest that the inability to mount a heterotypic antibody response to the infecting serotypes in young infants may have been an important factor in failure of the vaccines to induce protection.     

Mac ELISA测定乙脑患者血清和脑脊液中特异性IgM的评价

用抗体捕捉ELISA法(Mac ELISA)检测临床疑似流行性乙型脑炎(下称乙脑)病人脑脊液88份,阳性51份,阳性率57.95％;血清91份,阳性56份,阳性率为61.53％,两者无显著性差异(X~2=0.238 P>0.05);包括取自同一患者的脑脊液和血清各72份,阳性率分别为61.11％和68.05％;而分析其中14例IgG呈4倍以上增高,乙脑患者脑脊液IgM阳性13例,而血清IgM阳性却只有8例,提示在疫区流行季节内仅仅血清学IgM阳性有时可能为乙脑隐性感染的同时还伴其它有关病毒感染。     

Seroepidemiology of Chlamydia pneumoniae TWAR infection in Seattle families, 1966-1979.

Incidence rates of Chlamydia pneumoniae infection and information on reinfection and transmission within families were obtained by serologic study of serum samples from prospective family studies conducted 1966-1979. Specimens (n = 3671) from 343 subjects in 68 families were tested for TWAR antibody using the microimmunofluorescence assay. Acute infection was defined as a fourfold rise in antibody titer between consecutive specimens. Sixty-four episodes of infection were identified in 58 persons; 4 had 2 infections and 1 had 3. From late 1975 until early 1979, when 3 serum specimens were collected yearly, rates of infection by age groups 0-4, 5-9, 10-14, 15-19, and greater than or equal to 20 years were 0, 9.2, 6.2, 2.2, and 1.5/100 person-years, respectively. Reinfections, defined as infections in persons with previous antibody, constituted most acute infections among adults. Acute infections more often affected a single family member than multiple members, but 2 or 3 family members were infected during the same period 12 times.