Molecular and immunological studies of respiratory syncytial virus among Iraqi pediatric patients

Pediatric acute respiratory infections (ARI) are a substantial global source of pediatric morbidity and mortality. Pediatric acute respiratory infections can be divided into lower (LRT) and upper (URT) respiratory tract infections. URT includes: Laryngitis, otitis media, sinusitis, ear infections, Common colds (rhinitis), and pharyngitis. LRT includes: Bronchitis and pneumonia can result from the transmission of URT infections to LRT. Viruses are the primary cause of the great majority of (LRTI), they are approximately detected in 40% of cases. Human respiratory syncytial virus (hRSV) is a particularly prevalent source of severe lower respiratory infection in newborns, accounting for 3.4 million hospital admissions in developing countries for LRTIs among children under the age of five. The symptoms of hRSV include rhinorrhea, sneezing, low-grade fever and cough. The viral particle is a non-segmented, negatively sense RNA genomic (-ssRNA) with a total length of 15.2 kb. It has three surface glycoproteins: fusion protein F, attachment protein G, and the last glycoprotein, small hydrophobic protein SH. hRSV is separated into 2 distinct categories or subtypes, RSV-A and RSV-B, dependent on sequence-based characteristics associated with RSV (G). This study was conducted on 100 infants and children under 5 years with 62 males and 38 females, and the control group was 20 (14 males and 6 females). Two nasopharengeal swaps were taken from participants in this study. Besides, three milliliters of blood were collected for immunological studies. Viral RNA Extraction from clinical samples were done by automated machine. After that one step real time PCR was done for all clinical samples. The demographic distribution of clinical samples regarding gender was 38% female and 62% male (5 vs17). The most three common signs and symptoms were fever (85%), rhinorhoea (72%), and wheezing (66%). For RNA automated extraction, the appearance of all curves from all tested samples for automated RNA extraction with CT less than 33 indicates efficient RNA extraction method and success of RT-PCR process. The results showed that infection rate with hRSV was 22% (22 out of 100), other 78% considered as other respiratory tract infection related pathogens such as other virus and bacteria. According to genotype, type B hRSV is more than a subgroub (12 vs 10). The number of positive samples in the age group 1-6 months showed the highest number 14 out of 22 (63.6%) compared to age groups 6-12 and > 12 months (4 for each). Higher percent of hRSV positivity observed in patients who had pneumonia 59.09% (13 out of 22), followed by bronchiolitis 31.81% (7 out of 22) and other chest infections 9.09% (2 out of 22). The effects of these risk factors were statistically non significant (P>0.05). The solid sandwich ELISA assay was performed for the detecting the serum levels of cytokines from the T helper Th-1 phenotypes (IFN-γ) as a protective mediator and IL-8 as a deleterious mediator in 22 positively infants and young children with hRSV infection (17 male and 5 female). The level of IL-8 was increased significantly (p<0.05) in patients with hRSV in comparison to the control group, while the level of IFN-γ is decreased significantly (p<0.05) in hRSV patients in comparison to the control group.