The role of wild waterbird in spreading avian influenza virus subtype H5N1 at Pulau Dua Nature Reverse

Abstract

Waterfowls such as ducks, muscovy, and swans are natural reservoir of influenza virus subtype H5N1. In natural reservoir, the AI virus is Low Pathogenic Avian Influenza (LPAI). Instead of domestic waterfowls, wild waterbird species could also have a role in spreading AI subtype H5N1 virus. So far LPAI have been isolated from 105 species of wild birds, most of them were from Anseriformes and Charadiiformes order. Presumption that wild birds and migratory birds have a role in spreading AI virus, has not been proven until now because the intensive research has not been done. The mortality rate of wild waterbirds that reported in several countries, had not clearly explained the cause of death. The objectives of this research were (1) to estimate the seroprevalence of AI virus subtype H5N1 from residence wild waterbirds, in Pulau Dua Nature Reverse; (2) to identify the Mx gene as resistant anti viral gene from AI virus in wild waterbirds; (3) to identify the presence of AI virus subtype H5N1 on residence waterbirds in Pulau Dua Nature Reverse, also to observe the potential of wild waterbirds as reservoir for spreading AI virus subtype H5N1 The serological test to detect the presence of antibody antiviral AI virus subtype H5N1 was used to determine the exposure of AI virus subtype H5N1 among wild waterbirds in CAPD. Since antibody is the substance that appear in individual exposed when they are exposed by the strange antigen. The serosurveillans from wild waterbirds in CPAD had been done in 2008, 2010 and 2011. Serological test by Haemagglutinin-inhibition (HI) showed that six from nine species of residence wild waterbirds in CPAD produced antibody AI virus H5N1. It is explain that that those species were exposed by AI virus subtype H5N1 with low antibody titer. The low antibody titer can be caused by several factors such as AI virus exposure occurring indirectly, there was a small number of virus that exposure to wild waterbirds, the exposure time was very short, and the virus was low pathogenic. Indirect transmission occurred through the water as the source of drinking water for wild and domestic waterbirds, through saliva and nasal secretions and feces. Water as a media for transmission virus where there were interactions between wild waterbirds, waterfowls and domestic birds. Mx protein as part of dynamin super family (GTP ase) is a part of the innate immune system. Mx proteins were known to have the ability to inhibit the replication of various viruses. Mx protein coded by Mx genes that specifically anti-viral influenza in several animals. Mx gene was the one of the several genes that regulated myxovirus resistance. DNA of eight wild waterbirds species and three domestic birds (chicken, duck and Muscovy) around CAPD were examined by PCR using NE-F2 and NER2/ R primer obtaining PCR product with a length of 100 bp band. It indicated that most birds could have 100 bp band. These results explained that the Mx gene in residence wild waterbirds from CAPD could be the same as in the chicken, muscovy and duck. The results of PCR-RFLP in wild waterbirds and domestic waterfowls using the restriction enzyme RsaI showed band in 73 bp length (only have GG genotype). It informed that there was no polymorphism because all fragments display only one band (73bp ) in wild waterbirds and domestic waterfowls (muscovy and duck) around CAPD showed. In chickens, the 73 bp fragment (GG genotype) showed low antivirus activity because it has sensitive Mx gene (allele Mx-) and responsive to AI virus subtype H5N1 attack. This is not happened to ducks, muscovy, and wild waterbirds, although they have only one band (Mx- alleles). It was not caused death or clinical symptoms by the exposure of AI virus subtype H5N1. The virus identification by RT-PCR with primer used in identification of HA subtypes H5. Forward primers was H5 Kha-1 and reverse H5 Kha-3primer pair. The identification results of HA subtypes H5 in residence wild waterbirds in CAPD showed that the H5 subtype was not detected in these wild waterbirds. This was showed by the absence of positive bands that indicate the presence of the AI virus subtypes H5 in wild waterbirds. The absence of AI virus subtype H5N1 in nine species of residence wild waterbirds including Ciconiformes and Pelecaniformes order showed that these birds do not have the potential as a reservoir for AI virus subtype H5N1. It gives the information that birds are not a suitable host for the cultured AI virus subtype H5N1, so that there were no viral shedding into the environment from residence wild waterbirds.