Serological Studies in Infectious Mononucleosis

Serological investigations performed on 27 patients with illnesses resembling infectious mononucleosis showed a significant increase in high antibody titres (more than 1:40) to EB virus in 11 of the 12 who developed heterophile antibodies. Two of these patients, however, had a significant increase in antibody titre to cytomegalovirus and rubella virus, respectively. Of 15 patients who failed to develop heterophile antibodies, one had a high antibody titre to EB virus, the others generally having undetectable or low antibody titres. The insidious onset of the illness in many patients together with the fact that EB virus antibodies rose to high titres rapidly reduced the value of this investigation diagnostically.EB virus antibody was still present in the sera of five patients who had had well-authenticated heterophile-antibody-positive infectious mononucleosis some four to seven years previously. Twenty-seven out of 70 (39%) healthy nurses had antibody at a level of more than 1:10 to EB virus. The presence of EB virus antibody in different population groups appears to be related to such factors as age and socioeconomic status.     

Infectious Mononucleosis and its Relationship to EB Virus Antibody: A JOINT INVESTIGATION BY UNIVERSITY HEALTH PHYSICIANS AND P.H.L.S. LABORATORIES

In October 1969 tests made on 1,457 students entering English universities and colleges showed that 57% already possessed antibody to EB virus. The students without antibody in these initial tests were retested seven months later and by then 12% had acquired antibody. In about one-third of them the acquisition of antibody was not associated with any illness. In about 20% respiratory and other illness had occurred, but these symptoms were almost equally frequent in students who had not acquired antibody. Nearly half had developed infectious mononucleosis. In students in whom the acquisition of EB virus antibody was associated with the clinical and haematological manifestations of infectious mononucleosis the Paul-Bunnell test was almost invariably positive. In contrast, when these manifestations were not associated with the acquisition of EB virus antibody the Paul-Bunnell test was always negative.Tests for cytomegalovirus antibody were also made on the students at entry. The proportion of students with this antibody was much less (30%) and only a small proportion (1·4%) of those without antibody had acquired cytomegalovirus antibody seven months later. In the only patient in whom the acquisition of cytomegalovirus antibody alone was associated with the clinical and haematological features of infectious mononucleosis the Paul-Bunnell test was negative.     

Serological Response of the EBV Antibodies in Pediatric Cases of Infectious Mononucleosis and in Their Contacts

The EBV antibodies were measured in 378 sera from a group of 129 pediatric and older cases of infectious mononucleosis and from 117 family and social contacts. Cases of infectious mononucleosis with only one exception were EBV seropositive in acute and/or convalescent sera. Fourteen cases, however, from whom no convalescent serum was available were EBV seronegative. A rise in EBV antibodies of two dilutions or more was demonstrated in 15 of the 129 cases. The prevalence of these antibodies in contacts reached 50 to 70% in each of four age groups. A significant antibody rise was encountered in only four cases, one of whom was found to have infectious mononucleosis simultaneously with the index case and one after an interdisease period of 10 months. The infectivity of the EB virus (and of infectious mononucleosis if causally related) and its horizontal transmission seem to be as low in nature as they appear to be experimentally in the laboratory.     

Angioimmunoblastic lymphadenopathy after infectious mononucleosis.

Angioimmunoblastic lymphadenopathy occurred in a 46-year-old man 16 months after an episode of infectious mononucleosis induced by Epstein-Barr (EB) virus. The features of infectious mononucleosis included fever, pharyngitis, lymph gland enlargement, hepatosplenomegaly, hyperbasophilic mononuclear cells, and IgM antibodies to EB virus, although heterophile antibodies were not detected. The illness was severe and prolonged and included an asymptomatic measles virus infection. Over a year later massive enlargement of the lymph nodes led to a biopsy, which showed a diffuse infiltration with lymphoid cells and a proliferation of arborising small vessels typical of angioimmunoblastic lymphadenopathy. In spite of corticosteroids, levamisole, chlorambucil, and radiotherapy, no remission occurred, and serious infections led to death 18 months after the onset. Viral infections with EB virus and measles virus associated with pre-existing or subsequent immunological changes probably resulted in the appearance of angioimmunoblastic lymphadenopathy.     

Epstein-Barr virus mRNA export factor EB2 is essential for production of infectious virus

The splicing machinery which positions a protein export complex near the exon-exon junction mediates nuclear export of mRNAs generated from intron-containing genes. Many Epstein-Barr virus (EBV) early and late genes are intronless, and an alternative pathway, independent of splicing, must export the corresponding mRNAs. Since the EBV EB2 protein induces the cytoplasmic accumulation of intronless mRNA, it is tempting to speculate that EB2 is a viral adapter involved in the export of intronless viral mRNA. If this is true, then the EB2 protein is essential for the production of EBV infectious virions. To test this hypothesis, we generated an EBV mutant in which the BMLF1 gene, encoding the EB2 protein, has been deleted (EBV(BMLF1-KO)). Our studies show that EB2 is necessary for the production of infectious EBV and that its function cannot be transcomplemented by a cellular factor. In the EBV(BMLF1-KO) 293 cells, oriLyt-dependent DNA replication was greatly enhanced by EB2. Accordingly, EB2 induced the cytoplasmic accumulation of a subset of EBV early mRNAs coding for essential proteins implicated in EBV DNA replication during the productive cycle. Two herpesvirus homologs of the EB2 protein, the herpes simplex virus type 1 protein ICP27 and, the human cytomegalovirus protein UL69, only partly rescued the phenotype of the EBV(BMLF1-KO) mutant, indicating that some EB2 functions in virus production cannot be transcomplemented by ICP27 and UL69.     

Haemagglutination-inhibiting antibodies to B.K. virus in Hungary.

Antibody inhibiting the haemagglutination by B.K. virus was found in 64% of the serum samples collected from 949 subjects in Hungary. The frequency of seropositivity was the lowest (17%) among infants 1 and 2 years of age and the highest (93%) in the age group 16 to 20 years. The subsequent age groups showed a slow continuous decline. The age-distribution curve drawn on the basis of the geometric means of titres has two peaks, one between 3 and 5 years of age and another between 21 and 30 years of age, reaching 6.74 and 7.05, respectively, as expressed in terms of log2 units. The prevalence of haemagglutination-inhibiting antibody to B.K. virus in Hungary and its distribution by age are similar to those reported from other European countries.     

Cytomegalovirus in the mononucleosis syndrome in children

In 7 children aged 18 months to 7 years isolated from a group of 128 children with infectious mononucleosis the cytomegalovirus infection was found. Infection was diagnosed by determination of antibodies against immediate early and late CMV antigen by means of the ELISA test. Besides that, antibodies were determined against the capsid antigen and early antigen of EB virus by the method of indirect immunofluorescence. In four children only cytomegalovirus infection was found and three had a mixed infection with both viruses and the diagnosis in these cases was: infectious mononucleosis (due to EBV) with coexistent or following CMV infection. In the sera of two children with cytomegalovirus mononucleosis changes were observed in the antibodies against EBV which is explained as a result of interactions between CMV and EBV in the organism of the host.     

Epstein-Barr virus infection in the neonatal period and in childhood

In an attempt to detect and characterize congenital, neonatal and early childhood EBV infections, a prospective sero-epidemiological study was undertaken in 112 newborn infants and their mothers, 25 additional newborns undergoing exchange transfusion, 114 randomly selected hospitalized infants aged 0 to 3 years, and 109 siblings and parents of these infants. Leukocyte culture was attempted in all the newborns and in 25 pre- and post-transfusion.The findings of EBV seroconversion in six patients without clearly apparent illness, infectious mononucleosis in only one case with significant EBV antibody rise, seroreversion in three cases in early childhood, higher newborn than maternal EBV antibody titres in three cases and the establishment of two permanent lymphoblastoid cell lines from newborns following exchange transfusion raise the possibility of abortive primary EBV infection in early life. Congenital or neonatal infections following exchange transfusions, however, could not be substantiated with certainty since the EBV antibodies did not persist at follow-up except possibly in two cases. Parenteral transmission of the EB virus by exchange transfusion at birth is probably prevented by the presence of EBV antibodies in either donor or recipient.     

Monoclonal antibodies to the spike protein of feline infectious peritonitis virus mediate antibody-dependent enhancement of infection of feline macrophages.

Antibody-dependent enhancement of virus infection is a process whereby virus-antibody complexes initiate infection of cells via Fc receptor-mediated endocytosis. We sought to investigate antibody-dependent enhancement of feline infectious peritonitis virus infection of primary feline peritoneal macrophages in vitro. Enhancement of infection was assessed, after indirect immunofluorescent-antibody labelling of infected cells, by determining the ratio between the number of cells infected in the presence and absence of virus-specific antibody. Infection enhancement was initially demonstrated by using heat-inactivated, virus-specific feline antiserum. Functional compatibility between murine immunoglobulin molecules and feline Fc receptors was demonstrated by using murine anti-sheep erythrocyte serum and an antibody-coated sheep erythrocyte phagocytosis assay. Thirty-seven murine monoclonal antibodies specific for the nucleocapsid, membrane, or spike proteins of feline infectious peritonitis virus or transmissible gastroenteritis virus were assayed for their ability to enhance the infectivity of feline infectious peritonitis virus. Infection enhancement was mediated by a subset of spike protein-specific monoclonal antibodies. A distinct correlation was seen between the ability of a monoclonal antibody to cause virus neutralization in a routine cell culture neutralization assay and its ability to mediate infection enhancement of macrophages. Infection enhancement was shown to be Fc receptor mediated by blockade of antibody-Fc receptor interaction using staphylococcal protein A. Our results are consistent with the hypothesis that antibody-dependent enhancement of feline infectious peritonitis virus infectivity is mediated by antibody directed against specific sites on the spike protein.     

Infectious mononucleosis at the United States Military Academy. A prospective study of a single class over four years

A prospective study of EB virus infections was initiated in July, 1969 in the entering class of 1401 cadets, at the U.S. Military Academy at West Point, N.Y. and continued over 4 yr. On entry 63.5% possessed EBV antibody and 36.5 lacked EBV antibody. The rate of antibody prevalence varied with the geographic area from which the cadet originated.Except in two cadets already ill on first bleeding no evidence of clinical infectious mononucleosis (I.M.) occurred over the 4 yr period in the 890 cadets entering the Academy with EBV antibody. Among 437 cadets without antibody on entry, 54 or 12.4% were infected (seroconverted) in the freshman year; 15 of these had clinical I.M., 12 had suggestive I.M., and 39 had no known mono-like illness. The annual infection rates in susceptible cadets in the second, third, and fourth years were 24.4, 15.1, and 30.8 per 100, respectively. Of 201 cadets infected with EBV over 4 yr only 26.4% were manifested by heterophile positive clinical infectious mononucleosis. Overall, 46% of the 437 cadets entering without EBV antibody became infected over 40 mo of serologic observation; definite clinical infectious mononucleosis developed in 53 cadets, a clinical attack rate of 12.1 per 100 for 4 yr. The EBV infection rate among exposed and susceptible roommates of known cases was no higher than in roommates not so exposed.Elevations of EBV-specific and total IgM occurred during acute illness and disappeared in late convalescence. Total IgG and IgA levels were less commonly elevated. EBV-specific-IgM antibody was demonstrable during the acute illness but was absent 12 mo later. Analysis of EBV infection rates revealed no difference among persons of different ABO blood groups.     

特发性血小板减少性紫癜与巨细胞病毒、EB病毒感染相关性

目的：探讨小儿特发性血小板减少性紫癜（ITP）与巨细胞病毒、EB病毒感染的关系。方法：实验组：48例确诊断为ITP患儿,对照组：44例同期呼吸道感染患儿,应用酶联免疫吸附法（ELISA）对两组小儿外周血进行巨细胞病毒IgM抗体（HCMV-IgM）、EB病毒感染IgM抗体（EB-IgM）检测。结果：48例ITP患儿中HCMV-IgM抗体阳性者20例,阳性率为41.67%,明显高于对照组,两组之间差异有显著性（P〈0.01）;EBV-IgM抗体阳性者14例,阳性率为29.17%,明显高于正常对照组,两组之间差异有显著性（P〈0.05）。结论：1、巨细胞病毒感染是引起特发性血小板减少性紫癜的重要原因之一,且通过临床观察巨细胞病毒感染引起的ITP患儿病情重,病程长,治疗时间长,转为慢性ITP的可能性大;2、EB病毒感染可能是引起特发性血小板减少性紫癜的原因之一,并且EB病毒感染引起的特发性血小板减少性紫癜病情也偏重。     

141例小儿感染性腹泻临床特征及流行病学分析

目的:探讨儿童感染性腹泻(Infectious diarrhea,ID)的临床特征及病原菌学流行病特点,为临床防治提供理论依据。方法:回顾性分析我院2010年2月至2014年2月收治并确诊的141例感染性腹泻患儿的粪便培养结果,观察并总结患者体内大肠埃希菌、痢疾杆菌、肺炎克雷伯菌病毒等常见致病细菌的分布情况。结果:儿童感染性腹泻四季均可发病,夏季发病率最高,春季最低;年龄为1月~3岁的患儿感染性腹泻细菌及病毒感染比例显著高于其他两组(P0.05);141例患儿中,细菌阳性23例(16.3%),病毒培养阳性94例(66.7%)。各种病毒感染与患儿性别无关(P0.05)。结论:小儿感染性腹泻四季均较常见,病毒感染比例高于细菌感染比例,应根据病原菌分布情况积极采取预防与控制措施。     

Diametrically opposed effects of hypoxia and oxidative stress on two viral transactivators

Background

Hepatitis C virus (HCV) infection is a major public health problem with more than 170 million cases of chronic infections worldwide. There is no protective vaccine currently available for HCV, therefore the development of novel strategy to prevent chronic infection is important. We reported earlier that a recombinant human antibody clone blocks viral NS3 helicase activity and inhibits replication of HCV 1b virus. This study was performed further to explore the mechanism of action of this recombinant antibody and to determine whether or not this antibody inhibits replication and infectivity of a highly efficient JFH1 HCV 2a virus clone.

Results

The antiviral effect of intracellular expressed antibody against the HCV 2a virus strain was examined using a full-length green fluorescence protein (GFP) labeled infectious cell culture system. For this purpose, a Huh-7.5 cell line stably expressing the NS3 helicase gene specific IgG1 antibody was prepared. Replication of full-length HCV-GFP chimera RNA and negative-strand RNA was strongly inhibited in Huh-7.5 cells stably expressing NS3 antibody but not in the cells expressing an unrelated control antibody. Huh-7.5 cells stably expressing NS3 helicase antibody effectively suppressed infectious virus production after natural infection and the level of HCV in the cell free supernatant remained undetectable after first passage. In contrast, Huh-7.5 cells stably expressing an control antibody against influenza virus had no effect on virus production and high-levels of infectious HCV were detected in culture supernatants over four rounds of infectivity assay. A recombinant adenovirus based expression system was used to demonstrate that Huh-7.5 replicon cell line expressing the intracellular antibody strongly inhibited the replication of HCV-GFP RNA.

Conclusion

Recombinant human anti-HCV NS3 antibody clone inhibits replication of HCV 2a virus and infectious virus production. Intracellular expression of this recombinant antibody offers a potential antiviral strategy to inhibit intracellular HCV replication and production.     

A region of the Epstein-Barr virus (EBV) mRNA export factor EB2 containing an arginine-rich motif mediates direct binding to RNA

The Epstein-Barr virus (EBV) protein EB2 (also called Mta, SM, or BMLF1) has properties in common with mRNA export factors and is essential for the production of EBV infectious virions. However, to date no RNA-binding motif essential for EB2-mediated mRNA export has been located in the protein. We show here by Northwestern blot analysis that the EB2 protein purified from mammalian cells binds directly to RNA. Furthermore, using overlapping glutathione S-transferase (GST)-EB2 peptides, we have, by RNA electrophoretic mobility shift assays (REMSAs) and Northwestern blotting, located an RNA-binding motif in a 33-amino acid segment of EB2 that has structural features of the arginine-rich RNA-binding motifs (ARMs) also found in many RNA-binding proteins. A synthetic peptide (called Da), which contains this EB2 ARM, bound RNA in REMSA. A GST-Da fusion protein also bound RNA in REMSA without apparent RNA sequence specificity, because approximately 10 GST-Da molecules bound at multiple sites on a 180-nucleotide RNA fragment. Importantly, a short deletion in the ARM region impaired both EB2 binding to RNA in vivo and in vitro and EB2-mediated mRNA export without affecting the shuttling of EB2 between the nucleus and the cytoplasm. Moreover, ectopic expression of ARM-deleted EB2 did not rescue the production of infectious virions by 293 cells carrying an EBVDeltaEB2 genome, which suggests that the binding of EB2 to RNA plays an essential role in the EBV productive cycle.     

Infectious pancreatic necrosis (IPN) virus carriers and antibody production in a population of rainbow trout (Salmo gairdneri).

A total of three hundred and fifty-seven 2-year-old rainbow trout from a hatchery were examined for IPN virus over a period of 5 months. The overall virus isolation rate was 23.2%. The kidneys yielded virus most frequently while the spleen and pancreas-caeca yielded virus less frequently, and the gonads and feces yielded virus infrequently. During this period there was a decline in carrier rate as well as a decline in the numbers of infectious virions in the organs. These decreases were accompanied by elevated levels of neutralizing antibody in the sera. Fish with higher antibody levels were found to lose their IPN carrier status more frequently than those with lower antibody levels.     

Seroepidemiologic study of arbovirus infections in the north-east and south of Thailand

Blood specimens were collected from villagers in Khon-Kaen province, in the north-eastern region, and in Songkhla province, in the southern region of Thailand in the pre- and post-epidemic seasons of hemorrhagic fever. The hemagglutination inhibition antibody titers of the specimens were measured against dengue virus type 2, type 4, Japanese encephalitis virus and chikungunya virus. In general, Khon-Kaen villagers showed higher levels of HI antibodies against these arboviruses than Songkhla villagers and in both areas the antibody level against chikungunya virus, a group A arbovirus, was usually much lower than those against group B arboviruses. Specimens from Khon-Kaen province had such high antibody positive rates for group B arboviruses (80-100%) from an early age (3-4 years), in the pre-epidemic season, that scarcely any increase in the positive rate was observed in the post-epidemic season. The positive rate in specimens from Songkhla province was not so high in the pre-epidemic season and some increase was seen in the post-epidemic season, especially in lower age groups (3-4 to 7-9 years). The patterns of HI antibody titers in different age groups in the Khon-Kaen and Songkhla provinces were also compared. The patterns changed with increase of ages and were also different with different viruses. The patterns for chikungunya virus were quite different from those for dengue type 2, type 4 and Japanese encephalitis virus. These results suggest that people in Khon-Kaen are exposed to group B arbovirus infections more often in childhood and attain high antibody levels more rapidly than people in Songkhla.     

Translation of intronless RNAs is strongly stimulated by the Epstein–Barr virus mRNA export factor EB2

The Epstein–Barr virus protein (EB2) allows the nuclear export of a particular subset of early and late viral RNAs derived from intronless genes. EB2 is conserved among most herpesvirus members and its presence is essential for the production of infectious particles. Here we show that, besides its role as a nuclear export factor, EB2 strongly stimulates translation of unspliced mRNAs without affecting overall cellular translation. Interestingly, this effect can be reversed by the addition of an intron within the gene. The spliced mRNA is then efficiently exported and translated even in the absence of EB2. Moreover, we show that EB2 associates with translating ribosomes and increases the proportion of its target RNA in the polyribosomal fraction. Finally, testing of EB2 homolog proteins derived from EBV-related herpesviruses, shows that, even if they play similar roles within the replication cycle of their respective virus, their mechanisms of action are different.     

Dynamic antibody specificities and virion concentrations in circulating immune complexes in acute to chronic HIV-1 infection

Understanding the interactions between human immunodeficiency virus type 1 (HIV-1) virions and antibodies (Ab) produced during acute HIV-1 infection (AHI) is critical for defining antibody antiviral capabilities. Antibodies that bind virions may prevent transmission by neutralization of virus or mechanically prevent HIV-1 migration through mucosal layers. In this study, we quantified circulating HIV-1 virion-immune complexes (ICs), present in approximately 90% of AHI subjects, and compared the levels and antibody specificity to those in chronic infection. Circulating HIV-1 virions coated with IgG (immune complexes) were in significantly lower levels relative to the viral load in acute infection than in chronic HIV-1 infection. The specificities of the antibodies in the immune complexes differed between acute and chronic infection (anti-gp41 Ab in acute infection and anti-gp120 in chronic infection), potentially suggesting different roles in immunopathogenesis for complexes arising at different stages of infection. We also determined the ability of circulating IgG from AHI to bind infectious versus noninfectious virions. Similar to a nonneutralizing anti-gp41 monoclonal antibody (MAb), purified plasma IgG from acute HIV-1 subjects bound both infectious and noninfectious virions. This was in contrast to the neutralizing antibody 2G12 MAb that bound predominantly infectious virions. Moreover, the initial antibody response captured acute HIV-1 virions without selection for different HIV-1 envelope sequences. In total, this study demonstrates that the composition of immune complexes are dynamic over the course of HIV-1 infection and are comprised initially of antibodies that nonselectively opsonize both infectious and noninfectious virions, likely contributing to the lack of efficacy of the antibody response during acute infection.     

Seminal fluid excretion of cytomegalovirus related to immunosuppression in homosexual men.

Seminal fluid samples from 84 Danish homosexual men were successfully cultured to determine the prevalence of cytomegalovirus excretion. Ten (15%) out of 66 men positive for the antibody were found to be excreting the virus. Although the proportion excreting was inversely related to age (p less than 0.01), three men aged over 30 and with many years of homosexual experience excreted the virus. In addition, a 50 year old man with Kaposi''s sarcoma excreted the virus. A further study of the ratio of T cell helpers to suppressors in the men aged over 30 and a series of age matched non-excreting homosexual control or heterosexual men showed that those excreting cytomegalovirus in their seminal fluid had statistically lower ratios (all less than 0.77) than the controls (p less than 0.05). Excretion of cytomegalovirus may be related to re-emergence of latent infection in immunosuppressed homosexual men.