Epidemiology of 11 respiratory RNA viruses in a cohort of hospitalized children in Riyadh, Saudi Arabia.

Respiratory tract infections are a principal cause of illness and mortality in children worldwide and mostly caused by viruses. In this study, the epidemiology of 11 respiratory RNA viruses was investigated in a cohort of hospitalized children at a tertiary referral center in Riyadh from February 2008 to March 2009 using conventional and real-time monoplex RT-PCR assays. Among 174 nasopharyngeal aspirates, respiratory syncytial virus (RSV) was detected in 39 samples (22.41%), influenza A virus in 34 (19.54%), metapneumovirus (MPV) in 19 (10.92%), coronaviruses in 14 (8.05%), and parainfluenza viruses (PIVs) in 11 (6.32%). RSV, PIVs and coronaviruses were most prevalent in infants less than 6 months old, whereas MPV and influenza A virus were more prominent in children aged 7-24 and 25-60 months, respectively. The majority of the viruses were identified during winter with two peaks observed in March 2008 and January 2009. The presented data warrants further investigation to understand the epidemiology of respiratory viruses in Saudi Arabia on spatial and temporal basis.

Molecular characterization and phylogenetic analysis of human parainfluenza virus type 3 isolated from Saudi Arabia.

Human parainfluenza virus 3 (HPIV-3) is a leading cause of respiratory disease in children worldwide. Previous sequence analyses of the entire virus genome, among different HPIV-3 strains, demonstrated that HN is the most variable gene. There is a dearth of data on HPIV-3 strains circulating in Saudi Arabia. In this report, HPIV-3 was screened in nasopharyngeal aspirates collected from hospitalized children with acute respiratory disease during two successive seasons (2007/08 and 2008/09) using nested RT-PCR. Out of 73 samples collected during 2007/08, seven (9.59%) were positive; while 3 out of 107 samples collected during 2008/09 (2.8%) were positive. Virus isolation in cell culture was successful using HEp2, but not Vero cells. The identity of the isolated viruses was confirmed using immunofluorescence and neutralization assays. To elucidate the genetic characteristics and phylogeny of Saudi HPIV-3 strains, the complete HN gene sequence of two selected Saudi strains was analyzed in comparison to 20 strains isolated by others from different countries worldwide. Both strains showed the highest degree of sequence homology with Indian strains, followed by Chinese and most Japanese strains. Phylogenetic analysis confirmed that these strains fell into a distinct Asian lineage. This study is the first in Saudi Arabia to recover HPIV-3 isolates of confirmed identity, and to generate sequence data that may help in understanding virus diversity and evolution.

Human parainfluenza virus type 2 hemagglutinin-neuramindase gene: sequence and phylogenetic analysis of the Saudi strain Riyadh 105/2009.

BACKGROUND: Although human parainfluenza type 2 (HPIV-2) virus is an important respiratory pathogen, a little is known about strains circulating in Saudi Arabia. FINDINGS: Among 180 nasopharyngeal aspirates collected from suspected cases in Riyadh, only one sample (0.56%) was confirmed HPIV-2 positive by nested RT-PCR. The sample that was designated Riyadh 105/2009 was used for sequencing and phylogenetic analysis of the most variable virus gene; the haemagglutinin-neuramindase (HN). Comparison of HN gene of Riyadh 105/2009 strain and the relevant sequences available in GenBank revealed a strong relationship with Oklahoma-94-2009 strain. Phylogenetic analysis indicated four different clusters of HPIV-2 strains (G1-4). Twenty-three amino acid substitutions were recorded for Riyadh 105/2009, from which four are unique. The majority of substitutions (n=18) had changed their amino acids characteristics. By analyzing the effect of the recorded substitutions on the protein function using SIFT program, only two located at positions 360 and 571 were predicted to be deleterious. CONCLUSIONS: The presented changes of Riyadh 105/2009 strain may possess potential effect on the protein structure and/or function level. This is the first report that describes partial characterization of Saudi HPIV-2 strain.