Using atomic force microscope (AFM), we investigated the images of Pars influenza virus (PIV) under different treatment conditions and observed the different appearances of the virus and its ultra-microstructure from the exterior to the interior. From the 2D images under transmission electron microscope (TEM), we could see that the surfaces of PIV particles exhibited spherical and band-shaped 'tufts'; from the 3D images under AFM, we could further observe the whole spherical virus particles and their detailed surfaces, which exhibited round and band-shaped 'tufts'. Comparing the images under TEM with those under AFM, we found that the latter could reveal the surface topograph and ultramicrostructure of viruses more truly than did the former. The samples of viruses were treated by Tritonx-100, the lipid envelopes of virions were partly or completely resolved, and then most of their capsids were exposed. We could observe the different appearances of the virions under AFM, the lipid envelopes of which were gradually removed. The samples of viruses were also treated by SDS, and the RNA was released from the virions. From the AFM images, we could see the structure of the RNA. It was thus clear that AFM could be used to investigate the different appearances and ultramicrostructure of viruses rapidly and efficiently.
Microscopy, Atomic Force ; Parainfluenza Virus 1, Human ; ultrastructure ; Parainfluenza Virus 2, Human ; ultrastructure

Human parainfluenza viruses (HPIVs) is one of the main causes of acute respiratory tract infections in children. HPIVs have been grouped into four serotypes (HPIV1~HPIV4) according to serological and genetic variation. Different serotypes of HPIVs have diverse clinical disease spectrum, epidemic characteristics and disease burden. Based on the nucleotide variation in structural protein genes, HPIVs can be further divided into distinct genotypes and subtypes with diverse temporal and spatial distribution features. The standard molecular typing methods are helpful to clarify the gene evolution and transmission patterns of HPIVs in the process of population transmission. However, the development of molecular epidemiology of HPIVs has been hindered by the lack of a standardized molecular typing method worldwide. Therefore, this study reviewed the viral characteristics, genome structure, existing genotyping methods and evolution of HPIVs, and screened the reference strains for molecular typing, so as to improve the understanding of gene characteristics and molecular typing of HPIVs, and provide an important scientific basis for the monitoring and research of molecular epidemiology of HPIVs in China.
Child ; Humans ; Molecular Typing ; Parainfluenza Virus 1, Human/genetics* ; Parainfluenza Virus 2, Human/genetics* ; Parainfluenza Virus 3, Human/genetics* ; Paramyxoviridae Infections/epidemiology* ; Respiratory Tract Infections/epidemiology*

This study was performed to investigate the etiologic agents, age distribution, clinical manifestations and seasonal occurrence of acute viral lower respiratory tract infections in children. We confirmed viral etiologies using nasopharyngeal aspirates in 237 patients of the ages of 15 years or younger who were hospitalized for acute lower respiratory tract infection (ALRI) from March 1996 to February 1998 at Samsung Seoul Hospital, Seoul, Korea. The overall isolation rate was 22.1%. The viral pathogens identified were adenovirus (12.7%), influenza virus type A (21.1%), -type B (13.9%), parainfluenza virus type 1 (13.5%), -type 2 (1.3%), -type 3 (16.0%) and respiratory syncytial virus (21.5%). The occurrence of ALRIs was highest in the first year of life, although parainfluenza virus type 1 infection occurred predominantly in the second year of life and influenza virus caused illnesses in all age groups. The specific viruses are frequently associated with specific clinical syndromes of ALRI. The respiratory agents and associated syndromes frequently have characteristic seasonal patterns. This study will help us to estimate the etiologic agents of ALRI, and establish a program for the prevention and treatment. An annual nationwide survey is necessary to understand the viral epidemiology associated with respiratory illnesses in Korea.
Acute Disease ; Adenoviridae Infections/epidemiology ; Adolescence ; Age Distribution ; Animal ; Bronchitis/virology ; Bronchitis/epidemiology ; Cell Line ; Child ; Child, Hospitalized/statistics & numerical data ; Child, Preschool ; Croup/epidemiology ; Female ; Human ; Infant ; Influenza/epidemiology ; Influenza A Virus, Human ; Influenza B Virus ; Kidney/cytology ; Korea/epidemiology ; Liver/cytology ; Male ; Parainfluenza Virus 1, Human ; Parainfluenza Virus 2, Human ; Parainfluenza Virus 3, Human ; Paramyxovirus Infections/epidemiology ; Pneumonia, Viral/virology* ; Pneumonia, Viral/epidemiology* ; Respiratory Syncytial Virus Infections/epidemiology ; Respiratory Syncytial Viruses ; Respiratory Tract Infections/virology* ; Respiratory Tract Infections/epidemiology* ; Seasons

PURPOSE: Mycoplasma pneumoniae is the major cause of respiratory infections in school- aged children and young adults. This study aimed to investigate the epidemiological features of M. pneumoniae pneumonia in Korean children, between 1995 and 2003. METHODS: We retrospectively reviewed the medical record of 575 patients with M. pneumoniae pneumonia. In patients with pneumonia who visited Samsung Medical Center from January 1995 to December 2003, M. pneumoniae infection was confirmed by mycoplasma antibody titer > 1: 320 or four-fold increase. We analyzed age and sex distribution, monthly and annual epidemics, and mixed infection with respiratory viruses. RESULTS: The mean age was 4.49+/-2.80 years (range 0-16 years). There were 281 females and 294 males. The peak incidence was at 4 years of age (17.6 percent) and there were 333 person from 3 to 6 years of age (57.2 percent). Infants younger than 2 years accounted for 23.8 percent. M. pneumoniae pneumonia occurred mostly from September to December (64.8 percent) ; in November (18.1 percent), in December (16.2 percent), and in October (16.0 percent). Annual incidences were 9.6 percent in 1997 and 10.9 percent in 2000, 18.7 percent in 2003, respectively, while much lower incidences were noted in the other years. Seven cases showed mixed infection with respiratory viruses; adenovirus (n=3), RSV (n=2), Influenza virus (n=1), parainfluenza virus type 2 (n=1). CONCLUSION: In Seoul, Korea, epidemic outbreaks of M. pneumoniae pneumonia occurred every three years with peak incidences in the fall. These epidemiological data will be helpful for the prediction of occurrences of M. pneumoniae infection.
Adenoviridae ; Child* ; Coinfection ; Disease Outbreaks ; Epidemiologic Studies* ; Female ; Humans ; Incidence ; Infant ; Korea ; Male ; Medical Records ; Mycoplasma ; Mycoplasma pneumoniae ; Orthomyxoviridae ; Parainfluenza Virus 2, Human ; Pneumonia* ; Pneumonia, Mycoplasma ; Respiratory Tract Infections ; Retrospective Studies ; Seoul* ; Sex Distribution ; Tertiary Care Centers* ; Young Adult

PURPOSE: In this study, the clinical and epidemiological characteristics of patients admitted for viral croup were analyzed to evaluate disease severity based on the organism that caused the infection. METHODS: We retrospectively reviewed the medical records of 302 patients who were admitted to the Department of Pediatrics at the Wonju Severance Hospital between May 2013 and December 2016 for viral croup. Patients who showed positive results on multiplex polymerase chain reaction were subsequently diagnosed with respiratory virus infection. The Westley scoring system was used to evaluate the severity of viral croup. RESULTS: Of the 302 patients, 149 were admitted due to severe viral croup, including 88 boys and 61 girls, with a boy-to-girl ratio of 1.44:1. About 110 cases of parainfluenza virus infection have been reported, which accounted for almost half of the total cases. The other identified viruses included influenza virus, human rhinovirus, and respiratory syncytial virus. Analysis of the association between severe viral croup and causative pathogen revealed that only parainfluenza type 2 virus showed a significantly high risk. Parainfluenza type 2 virus did not show an age-based difference in frequency but showed relatively a higher frequency of infections during the summer and fall. CONCLUSIONS: In this study, parainfluenza virus type 2 was the only virus associated with severe viral croup. To facilitate proper preventive management, treatment, and prognosis evaluation of viral croup, prospective and multicenter studies should assess the additional variables and the severity of the virus. Additionally, further studies should be conducted to assess age-dependent influences, as well as the regional and seasonal incidence of viral infection.
Child ; Child, Hospitalized ; Croup ; Epidemiology ; Female ; Gangwon-do ; Humans ; Incidence ; Medical Records ; Multiplex Polymerase Chain Reaction ; Orthomyxoviridae ; Parainfluenza Virus 2, Human ; Paramyxoviridae Infections ; Pediatrics ; Prognosis ; Prospective Studies ; Respiratory Syncytial Viruses ; Retrospective Studies ; Rhinovirus ; Seasons ; Severity of Illness Index