Molecular characterization of human parainfluenza virus type 1 in infants attending Mbagathi District Hospital, Nairobi, Kenya

Abstract

Background. Human parainfluenza virus type 1 (HPIV-1), a Paramyxovirus, is a leading cause of paediatric respiratory hospitalizations globally. Currently, there is no HPIV-1 vaccine. Hence, there is need to characterize circulating strains of this virus to establish the feasibility of developing a vaccine against the virus. The variable HPIV-1 Hemagglutin-neuraminidase (HN) protein is found in the envelope of HPIV-1 where it initiates the infection process by binding to cellular receptors. HN is also the major antigen against which the human immune response is directed against. The present study focused on identifying mutations in the HN gene that would be useful in understanding evolution of HPIV-1.

Methods. 21 HPIV-1 isolates were obtained after screening nasopharyngeal samples from patients with influenza-like-illness. The samples were collected from Mbagathi District Hospital Nairobi from the period June 2006- December 2010. RT-PCR was carried out on the isolates using HN-specific primers to amplify a 360nt in the most polymorphic region and the amplicons sequenced. Genomic data was analysed using a suite of bioinformatic software.

Results. Forty-eight polymorphic sites with a total of 55 mutations were identified at the nucleotide level and 47 mutations at 23 positions at the amino acid level. There was more radical non-synonymous amino acid changes (7 positions) observed than conservative non-synonymous changes (1 position) on the HN gene fragment. No positively selected sites were found in the HN protein.

Conclusion.