[Pulmonary surfactant protein gene mutation associated with pediatric interstitial lung disease: a case study and the review of related literature].

OBJECTIVE: To report a case of pulmonary surfactant protein (SP) gene mutation associated with pediatric interstitial lung disease, and study the clinical diagnosis process and review of related literature, to understand the relationship between interstitial lung disease and SP gene mutation in infants and children. METHOD: The clinical, radiological, histological, and genetic testing information of a case of SP gene mutation related pediatric interstitial lung disease were analyzed and related literature was reviewed. RESULT: A 2-year-old girl without a history of serious illness was hospitalized because of the shortness of breath, cough, excessive sputum, and the progressive dyspnea. Physical examination on admission revealed tachypnea, slight cyanosis, and the retraction signs were positive, respiratory rate of 60 times/minute, fine crackles could be heard through the lower lobe of both lungs; heart rate was 132 beats/minute. No other abnormalities were noted, no clubbing was found. Laboratory test results: pathologic examination was negative, multiple blood gas analysis suggested hypoxemia. Chest CT showed ground-glass like opacity, diffused patchy infiltration. Bronchoalveolar lavage fluid had a large number of neutrophils, and a few tissue cells. Eosinophil staining: negative. Fluconazole and methylprednisolone were given after admission, pulmonary symptoms and signs did not improve, reexamination showed no change in chest CT. Then lung biopsy was carried out through thoracoscopy. Histopathology suggested chronic interstitial pneumonia with fibrosis. The heterozygous mutation of R219W in the SFPTA1 and the S186N in SFTPC were identified by SP-related gene sequencing. The review of related literature showed that polymorphisms at the 219th amino acid in SP-A1 allele were found in adults with idiopathic pulmonary fibrosis (IPF), but there is no related literature in pediatric cases. The patient in this report had a mutation at the SP-A1 allele consistent with related literature. Data of 17 young children with mutation in SP-C gene showed that all the 17 cases had dyspnea and tachypnea, chest CT revealed diffuse opacities in lungs, the pathology of lungs was NSIP and CPI. There were 17 kinds of mutation and the common mutation was I73T. The mutation of S186N in SFTPC in our case has never been shown in previously published literature. CONCLUSION: A case of interstitial lung disease with S186N gene mutation in SFTPC was preliminarily diagnosed in an infant. The SP-C gene mutations and polymorphisms are associated with pediatric interstitial lung disease.

Characterization of human metapneumovirus from pediatric patients with acute respiratory infections in a 4-year period in Beijing, China.

BACKGROUND: Human metapneumovirus (hMPV) was discovered by scientists in the Netherlands as a novel respiratory virus in 2001 and had been found in children with acute respiratory tract infections (ARTI) in China. The objective of this study was to determine the importance of hMPV infection in children in Beijing and the genotypes of the circulating virus by the surveillance during a four-consecutive-year period. METHODS: Clinical specimens collected from children with ARTI from January 2006 to December 2009 were tested for hMPV by RT-PCR using primers targeting the matrix (M) gene, followed by genotyping of hMPV directly from positive samples by diplex PCR with primers for glycoprotein (G) genes. Sequence analysis was used for genotyping of those un-typable samples. Common respiratory viruses in these clinical specimens were tested by virus isolation and antigen detection, in addition to hMPV detection. RESULTS: Of 4730 tested specimens, 191 (4.0%) were positive for hMPV and 62.8% of 191 were identified as genotype A. The positive rate of hMPV from hospitalized patients was higher than that from outpatients each year. Most of hMPV positive children were under five years old. The peak of hMPV activity mostly occurred in late spring and overlapped with or followed that of respiratory syncytial virus (RSV) and followed by parainfluenza virus 3. Of hMPV infected cases, 68.6% were lower respiratory tract infection, among which 79.4% were hospitalized, and upper respiratory tract infection was diagnosed for 31.4% of hMPV infected children. The 9.4% of hMPV positive samples were found to co-exist with other respiratory viruses. CONCLUSIONS: hMPV was an important pathogen for ARTI in pediatric patients, especially those under five years old. Both genotypes A and B circulated simultaneously in Beijing.

[Human metapneumoviruses were isolated from infants and children with acute respiratory infections in Beijing].

OBJECTIVE: To obtain isolated human metapneumovirus (HMPV) strains from clinical specimens collected from infants and children in Beijing and to promote the investigation on this important respiratory pathogen. METHOD: Clinical specimens including throat swabs from outpatients and nasopharyngeal aspirates from hospitalized children were collected from infants and children visited the affiliated children's hospital for acute respiratory infections during May 2008 to April 2009. HMPV positive specimens identified by RT-PCR and/or direct immunofluorescent assay with monoclonal antibody against HMPV were inoculated to LLC-MK(2) cells and incubated at 37°C and 33°C, respectively. The replication of the virus in the cells was detected by direct immunofluorescent assay followed by RT-PCR. The genotypes of the isolated virus strains were identified by RT-PCR. RESULT: Out of 1092 clinical specimens, 81 were HMPV positive by RT-PCR, the positive rate was 7.4% (81/1092). Among these positive specimens, 33 were inoculated to LLC-MK(2) cells and the replication of HMPV was revealed by antigen detection and RT-PCR from 5 out of these 33 inoculates. These isolated viruses could be passed in LLC-MK(2) cells and were not cross-reacted with other common respiratory viruses, such as ADV, RSV and Parainfluenza viruses 1/2/3 by monoclonal antibodies against these viruses in direct immunofluorescent assay. The HMPV was more likely to be isolated from fresh specimens within 24 hours after the collection of specimens which were not frozen. Four of the 5 isolated strains were identified as genotype A and 1 as genotype B. Unlike other respiratory viruses, these isolated HMPV did not show specific CPE in cell culture and the replication of the virus was identified by antigen detection and RT-PCR. CONCLUSION: HMPV of both genotypes were isolated from infants and children with acute respiratory infections in Beijing which will accelerate the investigation of this important virus.

[Identification and typing of adenoviruses from pediatric patients with acute respiratory infections in Beijing from 2003 to 2008].

OBJECTIVE: Adenovirus (ADV) is one of the most common causes of acute respiratory infections in infants and children. The objective of this study was to investigate the prevalence of adenovirus infection among pediatric patients with acute respiratory infections in Beijing and the types of the adenoviruses circulating in Beijing on the molecular bases. METHOD: Clinical specimens including throat swabs from outpatients and nasopharyngeal aspirates from hospitalized patients were collected from patients with acute respiratory infections in a consecutive period of 6 years from Jan 2003 to Dec 2008. Adenoviruses were identified from the collected clinical specimens by tissue culture and/or immunofluorescence assay and typed by nested-PCR based on the sequence of the encoding gene of hexon. Primers were designed for PCR amplification using hexon gene of adenovirus as target. One primer pair was designed as universal primers for amplifying a 1278 bp gene fragment located at the hexon gene of adenovirus types 3, 7, 11 and 21. Four primer pairs with the sequences located within the region of this 1278 bp fragment were designed specifically for amplifying adenoviruses types 3, 7, 11 or 21, respectively, which were used for a multiplex nest-PCR in a single tube. The products from this multiplex nest-PCR were 502 bp (for type 3), 311 bp (for type 7), 880 bp (for type 11) and 237 bp (for type 21), respectively, and the type of the adenovirus tested can be determined after agarose electrophoresis analysis of the PCR products. For those strains which could not be typed by the multiplex nest-PCR, the gene fragment was amplified by a universal primer pair for all adenovirus types from group A to F and the PCR products were sequenced directly. RESULT: Out of 17 941 clinical specimens collected, including 4378 throat swabs from outpatients and 13 563 nasopharyngeal aspirates from hospitalized patients, 304 were adenovirus positive by tissue culture and/or immunofluorescence assay, the overall positive rate was 1.69% (304/179 41). Among these 304 adenovirus positive specimens, 184 were by virus isolation and 184 by immunofluorescence assay, among which 64 were positive by both methods. The types of the adenoviruses were tested for 285 patients including 174 viral isolates and 111 clinical specimens. By using the multiplex nest-PCR, 272 were typable, including 174 (61.1%, 174/285) for ADV3, 92 (32.3%, 92/285) for ADV7, 6 for ADV11 (2.1%, 6/285) and no adenovirus type 21 was detected. Sequence analysis for those 13 nontypable specimens by the multiplex nest-PCR showed that 9 were ADV2 (3.2%, 9/285), 2 were ADV6 (0.7%, 2/285), 1 was ADV1 (0.4%, 1/285) and 1 was ADV5 (0.4%, 1/285). Most of the patients positive for adenovirus were under 5 years of age and 64.4% were from patients with lower respiratory infections, such as bronchiolitis and pneumonia. All the 5 cases of severe pneumonia with pulmonary failure were caused by ADV7 infection. CONCLUSION: Adenovirus is still an important pathogen for acute respiratory infection in infants and young children and most of the adenoviruses associated with acute respiratory infections in children in Beijing from 2003 to 2008 were ADV3 and ADV7. ADV7 could cause severe lower respiratory infections.

[Sequence analysis of the HA1 regions of hemagglutinin gene from influenza viruses (H3N2) isolated from children in Beijing in 2004 indicated antigenic variation].

OBJECTIVE: To identify variations in hemagglutinin genes from influenza viruses (H3N2) isolated from infants and young children with acute respiratory infection (ARI) between March, 2004 and April 2005. METHODS: RNAs from influenza A virus strains (subtype H3) isolated from specimens collected from ARI children were extracted followed by amplification for HA1 fragments from hemagglutinin (HA) genes by RT-PCR. The sequences of the fragments were defined by direct sequencing for the PCR products or the target inserts after the PCR fragments were cloned into the TA-cloning vector pBS-T and analyzed by bioinformatic software. RESULTS: Fragments of 987 bps of HA1 (encoding 329 amino acids) from a total of 32 strains of influenza A virus (subtype H3) isolated from the 2004 season and 1 from the 2003 season were amplified and the sequences were compared with vaccine reference strains recommended by WHO which were used in recent years. There were several consistent amino acid variations which involved in both antigenic epitopes A and B and receptor binding site (RBS) for isolated strains in the 2004 influenza season compared with the vaccine strains used during the recent years and the virus strains isolated in March 2004, indicated the antigenic drift of the viruses isolated in 2004 influenza season may lead to variant viruses. CONCLUSION: The variations of the HA genes from influenza virus (subtype H3) strains in the 2004-2005 influenza season were confirmed by sequence analysis for the HA1 regions of the hemagglutinin genes, which indicate that the antigenic drift would have been caused by the diversification of the genes and the efficacy of the recently used vaccines should be kept under close watch.