Respiratory syncytial virus infection in inbred mice.

Respiratory syncytial virus infected the nose and lungs of each of 20 strains of inbred mice, with viral titers varying 100-fold from least permissive to most permissive strains. Viral titers appeared to be under genetic control, but did not correlate with the H-2 haplotype.     

Respiratory syncytial virus infection in owl monkeys: viral shedding, immunological response, and associated illness caused by wild-type virus and two temperature-sensitive mutants.

Intranasal inoculation of owl monkeys with wild-type respiratory syncytial virus induced upper respiratory tract disease in each of seven animals. The response of owl monkeys to two highly defective, temperature-sensitive, multiple-lesion mutants was then compared to the pattern seen with wild-type respiratory syncytial virus. These mutants, ts-1 NG-1 and ts-1 NG-16, were derived from the ts-1 mutant that had been remutagenized with nitrosoguanidine (NG). Previously the ts-1 NG-1 and ts-1 NG-16 mutants had been shown to be more temperature sensitive and more stable genetically than their ts-1 parent. Both ts-1 NG-1 and ts-1 NG-16 produced infection that was delayed in onsent compared to wild-type virus infection. However, the mutants were shed from the upper respiratory tract for the same period of time and at the same titer as wild-type virus. The serum neutralizing antibody response to infection with the mutants was nearly equivalent to that elicited by wild-type virus. However, the extent of disease induced by the mutants was significantly less than that seen with wild-type virus. These observations suggest that the mutants are potential vaccine condidates and should be subjected to additional in vivo testing in primates and, ultimately, humans.     

Respiratory syncytial virus infection in the elderly

Respiratory syncytial virus (RSV) is the most common cause of lower respiratory tract infections in infants and children throughout the world. Respiratory syncytial virus infections in the elderly represent reinfections in hosts who have had many prior episodes. Thus, RSV infections are usually not considered serious in adults, since reinfections are generally known to result in mild disease. Nevertheless, in adults, as in children, the infection has been reported to cause altered airway resistance and exacerbation of chronic obstructive lung disease. In people over 60 years of age, RSV usually causes mild nasal congestion, but can also result in fever, anorexia, pneumonia, bronchitis, and even death. Diagnosis of RSV infection in the elderly by the standard methods used in children is not as successful as in the latter group. This may be due to a combination of factors such as shorter shedding phase, lower viral titers, and dry mucosa. An alternative, rapid, and direct viral diagnostic method, the polymerase chain reaction, has recently been introduced in the diagnosis of RSV infections.     

Respiratory syncytial virus infection in children with severe motor and intellectual disabilities

Children with severe motor intellectual disabilities (SMID) are at high risk of death from acute viral lower respiratory tract infections (LRTI). Although respiratory syncytial virus (RSV) is the most common cause of viral LRTI in children, there have been a few reports on the relationship between SMID and the severity of RSV-LRTI. The aim of the present study is to assess the influence of RSV-LRTI in children with SMID. A case–control study composed of children with SMID (n?=?18) and previously healthy children (n?=?43) less than 16 years old hospitalized for RSV-LRTI was performed during five consecutive RSV seasons. The clinical presentation and the laboratory data in the SMID group were compared with those in the non-SMID group. In the bivariate analysis, the median age of the SMID group was higher than that of the non-SMID group (p?=?0.002). Children with SMID had an increased risk for ventilation support (p?=?0.057). The count of neutrophils in the SMID group was significantly increased (p?=?0.012), whereas the proportion of bacterial co-infection was lower than that in the non-SMID group (p?=?0.005). Multivariate logistic analysis showed that SMID was associated with longer oxygen usage [>7 days: odds ratio (OR) 5.309, p?=?0.033]. The present study revealed that children with SMID were prone to developing hypoxia by RSV-LRTI. The strategies for the treatment and prevention of RSV infection need to be improved in SMID children.     

Respiratory syncytial virus infection in cyclophosphamide-treated cotton rats.

Cotton rats infected intranasally with respiratory syncytial virus and immunosuppressed with cyclophosphamide shed virus for at least 7 weeks. Dissemination of virus beyond the respiratory tract was observed. In contrast, virus was recovered from infected, non-immunosuppressed rats for only 1 week, and only from the respiratory tract.     

Screening,characterisation and prevention of Hepatitis B virus (HBV) co-infection in HIV-positive children in South Africa

BackgroundIn South Africa, the first HBV vaccine dose is administered at age 6 weeks, leaving a potential window for vertical transmission. Insights into HBV seroprevalence in the vulnerable HIV-infected group are important to drive improvements in surveillance, treatment and prevention.ObjectivesWe set out to implement a screening program for HBV among HIV-infected children and adolescents in Kimberley, South Africa. Our aims were to demonstrate that screening is feasible and sustainable, to establish the prevalence of HBV, to characterise the HBV cases we identified, and to inform discussion about the infant vaccination schedule.Study designWe tested all HIV positive children (age 0–16) for Hepatitis B surface antigen (HBsAg), delivering this testing as part of routine state-funded care. We followed up HBsAg-positive cases with an extended panel of HBV serology tests, and HBV DNA viral load quantification.ResultsOur screening campaign was successfully incorporated into routine out-patient care. Among 625 patients tested, we found five positive for HBsAg (0.8%), of whom three were Hepatitis B e-antigen positive. Two additional children initially tested HBsAg-positive but were negative on repeat testing. Antiviral therapy in the HBsAg children was reviewed and adjusted if required.ConclusionsThe results testify to the overall success of the HBV vaccine campaign. However, we have demonstrated that ongoing vigilance is required to detect cases and prevent transmission events. Further evaluation of the optimum timing of the first vaccine HBV vaccine dose is required; a vaccine dose at birth could reduce prevalence further.     

Molecular characterisation of type 1 polioviruses associated with epidemics in South Africa

The molecular epidemiology of wild-type 1 polioviruses isolated in South Africa during 2 major poliomyelitis epidemics in the 1980s and during the pre- and inter-epidemic periods was investigated by partial sequence analysis across the VP1/2A junction. Poliovirus-specific primers were used to amplify and subsequently sequence the region of interest. Viruses belonging to different genotypes were found to have been responsible for the 2 outbreaks. The Gazankulu outbreak in 1982 was caused by a poliovirus genotype which was unique to South Africa and which circulated endemically throughout much of the country between 1980 and 1985. Two additional genotypes, imported from the Middle East and West Africa, cocirculated endemically with the South African genotype between 1982 and 1985. The 1988 epidemic in Kwazulu-Natal was attributed to an imported genotype apparently introduced into South Africa in 1985 from countries north of the border. This genotype displaced the 3 genotypes previously in circulation and continued to be transmitted within the country until 1989, when the last confirmed cases of poliomyelitis associated with wild-type viruses were documented. All circulating wild-type poliovirus strains appear to have been eliminated from South Africa. J. Med. Virol. 52:42–49, 1997. © 1997 Wiley-Liss, Inc.     

Respiratory syncytial virus polypeptides: their location in the virion.

Purified respiratory syncytial (RS) virus contains, in addition to the six to seven polypeptides previously reported (S. Levine, 1977, J. Virol., 21, 427–431), a large polypeptide (VPO), MW > 160,000. Treatment of purified virus with trypsin removes the major glycoproteins, VP1 and 2. Treatment of purified virus with 2% Triton X-100 in HBSS (equivalent to 0.15 M NaCl) solubilizes the glycoproteins VP1 and 2 and a nonglycosylated protein, VP5, MW 28,000, which suggests that VP5 is an M protein. Treatment with 2% Triton X-100 in 0.4 M NaCl solubilizes all the virion proteins except VPO and VP3, which are also not solubilized in 0.8 M NaCl. The results suggest that VP3, MW 44,000, is the major nucleocapsid protein, and that VPO is not a superficial contaminant of the virus preparation, but instead is closely associated with the nucleocapsid. Only VP3 is present in nucleocapsids isolated from RS virus-infected cells by isopycnic centrifugation in CsCl.     

Molecular characterisation of HCV genotype 4 isolates circulating in Italy

The characteristics of genotype 4 subtype variability of HCV isolates circulating in Italy were studied. The viral isolates were identified from 736 HCV-RNA positive sera originated from seroepidemiological studies undertaken in 4 different regions of North, South Italy and Sardinia. 24 out of 28 genotype 4 isolates (86%) were classified by phylogenetic analysis of E1 genome region (915-1128) as belonging to subtype 4d (Neighbour Joining Method). Three isolates classified as subtype 4a were detected in haemophilic patients, possibly related to infections from blood products. One isolate classified as a new subtype derived from an Eritrean patient subjected to haemodialysis. Very high genome homogeneity (mean 4.3%) was shown by genetic comparisons (DNA dist programs Phylip Package) for all the 4d isolates relative to the studies performed in Veneto, Calabria and Sardinia and originated from subjects from the general population and outpatients (19 subtype 4d isolates out of 24). In the 3 studies different prevalence rates of HCV genotype 4 (3.1%, 1. 3%, 14% respectively) were found. In contrast a considerable degree of heterogeneity, both intragroup and with the other groups (mean 8. 2% and 8.7%, respectively) was observed among subtype 4d isolates identified in the patients of a haemodialysis centre in Apulia region. In conclusion the subtype 4d of genotype 4 was highly prevalent and endemic in Italy. An elevated level of viral heterogeneity was observed in one study carried out in a region of Southern Italy. This can be related to a longer period of past endemicity of this genotype and to a high level of exposure to reinfections in particular categories of patients such as haemodialysis patients.     

Molecular epidemiological analysis of community circulating respiratory syncytial virus in rural South Africa: Comparison of viruses and genotypes responsible for different disease manifestations

Human respiratory syncytial virus (RSV) is a major cause of severe lower respiratory tract infection in children in both the industrialized and developing world. Most molecular epidemiological studies have, until now, focused on isolates from hospitalized infants in industrialized countries. Limited data have been available with regard to community circulating RSV, especially from Africa. The present study compares RSV isolates from infants attending rural community clinics in the Northern province of South Africa, with isolates from hospitalized infants in Soweto, near Johannesburg, South Africa, during the same period. A multiplex nested polymerase chain reaction was developed for analyzing the clinical specimens, a technique that permits subtyping and nucleotide sequence analysis of the second variable region of the G-protein gene. Community- and hospital-based isolates from young children in South Africa, as well as isolates from Mozambique were compared phylogenetically. One subgroup B community isolate was identified that had a G-protein truncated by approximately 35 amino acids, however, the other community isolates were not significantly different from hospital isolates. Evidence was found that the same RSV genotypes and viruses could cause mild upper respiratory tract infections or lower respiratory tract infections or severe RSV in young infants.     

Respiratory syncytial virus group-specific antibody response in nasopharyngeal secretions from infants and children after primary infection.

Respiratory syncytial virus (RSV) group-specific immunoglobulin A (IgA) and IgG enzyme-linked immunosorbent assay antibody and neutralizing antibody responses were determined for nasopharyngeal secretions (NPS) from 27 infants and children (6 to 18 months of age) undergoing primary infection with RSV group A or B strain. IgA and IgG antibody responses against RSV envelope glycoproteins (fusion [F] and large [G] glycoprotein) in NPS were also analyzed. Most subjects examined developed moderate levels of NPS IgA and IgG antibodies and neutralizing antibody activity to both group A and B strains in convalescent phase; however, the levels of antibodies to homologous strains were significantly higher than to the heterologous strains. Patients infected with group A developed antibodies in both F and G glycoproteins of A2 strains (group A). Patients infected with group B developed levels of antibody activity to F glycoprotein of A2 strain similar to those of patients infected with group A. However, these subjects developed little or no antibody response to G glycoprotein of A2 strain. These data suggest that the IgA and IgG antibody responses to G glycoprotein in the respiratory tract are group specific. It is suggested that lack of antibody response to the G glycoprotein of the heterologous group in the respiratory tract may determine the outcome of reinfection with other RSV strains.     

Respiratory syncytial virus infection in immunocompetent and immunocompromised murine

The purpose of this study is to distinguish respiratory syncytial virus ( RSV) infection and immunology between immunocompetent and immunocompromised murine and to explore immune mechanism of RSV infection. At various time points after RSV infection of BALB/c mice and nude mice, pulmonary viral titers were assayed, RSV antigen was tested by direct immune-fluorescent assay and immu nohistochemistry. Pulmonary mRNA expressions of Toll like receptor (TLR)2 and TLR4 were assayed by RT-PCR. CD4 cells and CD8 cells in peripheral blood were examined by flow cytometry and plasma total IgE was assayed by ELISA. Leukocytes in bronchoalveolar lavage fluid (BALF) and pulmonary histology were identified to reflect airway inflammation. It was found that RSV titers of both mice peaked on the 3rd day post infection with a much higher level of viral titer in nude mice than in BALB/c mice and a longer viral duration in nude mice (over 9 days post infection) than in BALB/c mice (6 days post infection). RSV infection induced higher viral antigen expression in nude mice (0.267±0.045) than in BALB/c mice (0.168±0.031). RSV infection enhanced pulmonary TLR4 expression of BALB/c mice (51.96%±11.34%) and nude mice (48.96%±12.35%) compared with each control (34.04%±10.06% and 32.37%±9.87% respectively). CD4 peripheral blood cells increased in RSV infected BALB/c mice (66.51%±2.09%) compared with the control BALB/c mice (51.63%±5.90%), and CD4 cells and CD8 cells were deficient in nude mice. RSV infection increased plasma total IgE in both mice, and BALB/c mice had a larger amount of IgE on the 7th day post infection (9.02 ng/ml±2.90 ng/ml) and on the 14th day post infection (12.76 ng/ml±4.15 ng/ml) than corresponding nude mice (3.72 ng/ml±1.06 ng/ml and 7.62 ng/ml±3.08 ng/ml respectively on the 7th and 14th day post infection). RSV infected nude mice had more severe airway inflammation than infected BALB/c mice. It is concluded that BALB/c mice and nude mice presented similar RSV infectious characteristics. However, infection of nude mice showed higher viral titer with longer duration and more severe airway inflammation, lower level of plasm total IgE and CD4 peripheral blood cells, but the similar pulmonary TLR4 expression with BALB/c mice.