Serological evidence of ebola virus infection in indonesian orangutans

[tetano]

PLoS One. 2012;7(7):e40740. Epub 2012 Jul 18.
Serological evidence of ebola virus infection in indonesian orangutans.
Nidom CA, Nakayama E, Nidom RV, Alamudi MY, Daulay S, Dharmayanti IN, Dachlan YP, Amin M, Igarashi M, Miyamoto H, Yoshida R, Takada A.
Source

Avian Influenza-zoonosis Research Center, Airlangga University, Surabaya, Indonesia.
Abstract

Ebola virus (EBOV) and Marburg virus (MARV) belong to the family Filoviridae and cause severe hemorrhagic fever in humans and nonhuman primates. Despite the discovery of EBOV (Reston virus) in nonhuman primates and domestic pigs in the Philippines and the serological evidence for its infection of humans and fruit bats, information on the reservoirs and potential amplifying hosts for filoviruses in Asia is lacking. In this study, serum samples collected from 353 healthy Bornean orangutans (Pongo pygmaeus) in Kalimantan Island, Indonesia, during the period from December 2005 to December 2006 were screened for filovirus-specific IgG antibodies using a highly sensitive enzyme-linked immunosorbent assay (ELISA) with recombinant viral surface glycoprotein (GP) antigens derived from multiple species of filoviruses (5 EBOV and 1 MARV species). Here we show that 18.4% (65/353) and 1.7% (6/353) of the samples were seropositive for EBOV and MARV, respectively, with little cross-reactivity among EBOV and MARV antigens. In these positive samples, IgG antibodies to viral internal proteins were also detected by immunoblotting. Interestingly, while the specificity for Reston virus, which has been recognized as an Asian filovirus, was the highest in only 1.4% (5/353) of the serum samples, the majority of EBOV-positive sera showed specificity to Zaire, Sudan, Cote d'Ivoire, or Bundibugyo viruses, all of which have been found so far only in Africa. These results suggest the existence of multiple species of filoviruses or unknown filovirus-related viruses in Indonesia, some of which are serologically similar to African EBOVs, and transmission of the viruses from yet unidentified reservoir hosts into the orangutan populations. Our findings point to the need for risk assessment and continued surveillance of filovirus infection of human and nonhuman primates, as well as wild and domestic animals, in Asia.

PMID:
22815803
[PubMed - in process]


http://www.ncbi.nlm.nih.gov/pubmed/22815803

 

[mixin]

Re: Serological evidence of ebola virus infection in indonesian orangutans

ProMED discussion on this study:

This study suggests the existence of multiple species of filoviruses or unknown filovirus-related viruses in Indonesia, some of which are serologically similar to African EBOVs, and also hypothesizes that filoviruses or filovirus-related viruses might be more widely distributed in Asian countries than assumed hitherto. Isolation of the virus will be needed to confirm these results and to understand the ecology of filoviruses in Asia, particularly to answer following questions; (i) Is there any known filovirus species other than REBOV in Asia? (ii) Are Asian filoviruses comparatively low pathogenic and asymptomatically maintained in the nonhuman primate populations? (iii) Are the viruses introduced into primates from putative natural reservoir animals? (iv) Is there a risk of virus transmission to humans through contact with nonhuman primates and/or yet unidentified natural reservoir hosts in Asia?

Because the population density and numbers of orangutans in Indonesia do not seem to be high enough to maintain any virus that causes an acute infection, it seems unlikely that they could serve as reservoir hosts unless filoviruses are somehow able to cause chronic infection in orangutans, as is the case with a persistent infection model of measles virus, other member of the Mononegavirales [23]. Instead, they were presumably infected through direct or indirect contact with another animal species that might be the reservoir and/or amplifying hosts of filoviruses. However, we assume that some species of wild primates could be infected without significant illness and able to serve as carrier or amplifying hosts of filoviruses in some circumstances, as is suggested for other viral zoonotic diseases such as sylvatic yellow fever, chikungunya, and Kyasanur forest disease [24], [25], [26]. Whereas these are vector-borne diseases, possible roles of arthropods in the ecology of filoviruses have also been speculated [27].

A point to note is the high likelihood of an EBOV and MARV source, including as yet unknown species, in nature. It is possible that the filoviruses include diverse members with different pathogenicity and different perpetuation mechanisms. Indeed, a new filovirus, named Lloviu virus, was recently detected from long-fingered bats (_Miniopterus schreibersii_) in Spain [28]. This insectivorous bat species is widely distributed in Oceania, southern Europe, southern Africa, and southeast Asia [29]. Our findings emphasize the need for a joint risk assessment regarding filovirus infection in Asia at the interface between environment, domestic animals and human populations. Further laboratory and ecological investigations are needed to understand how fruit bats and nonhuman primates may play roles in maintaining filoviruses and potentially introducing them into humans.
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[It is important to note that the orangutans sampled were free-ranging, wild individuals captured in East (Kutai Kartanegara) and Central (Palangka Raya) Kalimantan provinces in Indonesia, not captive ones in zoos or other centers. The authors have clearly pointed out the need for further studies, not an easy task with these wild, solitary apes. Isolation of the viruses or extensive RNA sequences is critical to better understand which viruses are involved and their relationships to other filoviruses. It certainly seems reasonable to suspect that other, as yet undiscovered filoviruses are circulating in the primary forests where the orangutans live, perhaps infecting other vertebrate wild animals in that ecosystem.

http://www.promedmail.org/direct.php?id=20120806.1230473