Kliničke i molekularno-epidemiološke karakteristike infekcije humanim metapneumovirusom u Hrvatskoj

Ljubin Sternak, Sunčanica (2008) Kliničke i molekularno-epidemiološke karakteristike infekcije humanim metapneumovirusom u Hrvatskoj. PhD thesis, Sveučilište u Zagrebu.

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Abstract

Human metapneumovirus (HMPV) is an important respiratory pathogen, especially among young children. The aim of this study was to determine the incidence of HMPV infection in hospitalized children with acute respiratory tract infection (ARTI) in the season 2005/2006 in Croatia, as well as to perform the genotypic analysis of detected HMPV strains. From December 1 to March 31 2005/2006 nasopharyngeal secretions (NPSs) were collected from 402 inpatients up to 5 years of age with ARTI hospitalized in two clinics in Zagreb. NPSs were tested by real time RT-PCR assay targeting the nucleoprotein (N) gene of HMPV. To perform the phylogenetic study, partial nucleotide sequences were obtained for HMPV fusion (F) gene of 30 HMPV positive samples. HMPV was detected in 33 (8.2%), respiratory syncitial virus (RSV) in 101 (25.1%), adenoviruses in 41 (10.2%), parainfluenza viruses types1-3 in 24 patients (6.0%) and influenza viruses in 3 (0.7%) patients. The peak incidence of HMPV infection was detected in January (18/33). Three of 34 HMPV positive specimens were positive for other viral pathogens (1- parainfluenza virus type 3, 1- RSV, 1- adenovirus). No difference was noted between HMPV infected children and children infected with other viruses regarding to the sex. Children infected with adenovirus were significantly older than children infected with other viruses (HMPV, RSV and parainfluenza viruses). The majority of the infections caused by HMPV (69.7%) children presented with lower respiratory tract infections (LRTI). Comparative analysis of the clinical presentation of HMPV and RSV infected children revealed no significant differences between those two groups while adenoviruses and parainfluenza viruses caused more upper respiratory tract infections (URTI) than HMPV and RSV. Patient co-infected with parainfluenza virus type 3 and HMPV showed more severe clinical picture comparing to the clinical presentation of single-infection of HMPV in the same patient. Phylogenetic analysis showed the circulation of two main genetic lineages (A and B). It also showed the existence of two sublineages within the group B (B1 and B2) and three subclusters within lineage A (A1, A2a and A2b). The most prevalent subtype was the genotype B2 (15/30), followed by B1 (11/30), while group A of HMPV was detected in only four specimens. Interestingly, for one A2b genotype isolate epidemiological data suggests importation from Germany. All patients infected with HMPV genotype A had clinical presentation of LRTI, while 36% (9/25) of those infected with genotype B had URTI. All strains detected from patients infected with HMPV alone who required supplemental oxygen belonged to the genotype B2, while two HMPV strains from patients with co-infection who received supplemental oxygen belonged to the genotype B1. Evaluation of HMPV incidence contributes to the etiology of ARI in Croatia, while genotyping of the HMPV strains from Croatia contributes to the data of the genetic variability and molecular epidemiology of the virus in the region and in the world.

Abstract in Croatian

Humani metapneumovirus (HMPV) jedan je od važnih uzročnika akutnih infekcija dišnog sustava (ARI), osobito u male djece. Cilj ovog rada bio je odrediti incidenciju HMPV-a u hospitalizirane djece mlađe od 5 god. s ARI u zimskoj sezoni 2005/2006, kao i analizirati genetsko ustrojstvo dokazanih HMPV sojeva. U razdoblju od 1. prosinca 2005. do 31. ožujka 2006. prikupljeni su nazofaringealni sekreti (NFS) 402 djece do 5 godina starosti oboljele od ARI hospitalizirane u dvije zagrebačke klinike. NFS su testirani metodom RT-PCR u stvarnom vremenu s početnicama koje dokazuju gen za nukleoprotein (N) HMPV-a. U svrhu izrade filogentetskog stabla, umnožen je, detektiran i sekvenciran dio gena koji kodira fuzijski (F) protein u 30 uzoraka pozitivnih na N gen HMPV-a. HMPV infekcija dokazana je u 33/402 bolesnika (8,2%), infekcija respiratornim sincicijskim virusom (RSV) u 101 (25,1%), adenovirusima u 41 (10,2%), virusima parainfluence tipa 1, 2 ili 3 u 24 bolesnika (6,0%) i virusom influence A u 3 (0.7%) bolesnika. Vrh incidencije HMPV infekcije zabilježen je u siječnju 2006. god. U tri pacijenta dokazana je koinfekcija s još jednim respiratornim virusom (1 parainfluenza virus tip 3, 1 RSV, 1 adenovirus). Djeca inficiran HMPV-om nisu se razlikovala po spolu u odnosu na djecu inficiranu nekim drugim virusom. S obzirom na dob, djeca inficirana adenovirusom bila su značajno starija od djece inficirane HMPV-om, RSV-om ili virusima parainfluence. Većina infekcija uzrokovana HMPV-om (69.7%) bila je infekcija donjeg dišnog susutava (IDDS). Usporedbom učestalosti klinčkih sindroma uzrokovanih pojedinim virusima nismo pronašli razliku u djece inficirane HMPV-om i RSV-om, dok su djeca inficirana adenovirusom i virusima parainfluence imala češće infekcije gornjeg dišnog sustava (IGDS) u odnosu na djecu inficiranu HMPV-om i RSV-om. U bolesnika s koinfekcijom virusom parinfluence tip 3 i HMPV-om uočena je teža klinička slika u odnosu na kliničku sliku koju je bolesnik pokazivao kada je bio inficiran samo s HMPV-om. Filogenetska analiza sojeva dokazala je cirkulaciju dviju glavnih genetičkih linija HMPV-a (A i B). Dokazne su i dvije podgrupe unutar grupa A i B ( A1, A2, B1 i B2), te dvije varijante unutar podgrupe A2 (A2a i A2b). Najčešći dokazan podtip bio je podtip B2 (15/30) zatim slijedi B1 (11/30), dok je genotip A dokazan u samo četiri uzorka. Epidemiološki podaci ukazuju da je jedna od dokaznih varijanti A2b bila uvezena iz Njemačke. Svi bolesnici inficirani HMPV genotipom A imali su kliničku sliku IDDS (4/4). IGDS je malo 36% (9/25) djece inficirano genotipom B. U sve djece koja su primala kisik a bila inficirana isključivo s HMPV-om dokazan je podtip B2, dok je kod koinficirane djece koja su primala kisik dokazan podtip B1. Određivanje učestalosti HMPV-a značajan je doprinos etiologiji virusnih ARI u Hrvatskoj, a genotipizacija autohtonih sojeva iz Hrvatske molekularnoj epidemiologiji ovog virusa u regiji i svijetu.

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