Ghanaian bat henipavirus (GhV), also known Kumasi virus (KV), belongs to the genus Henipavirus in the family Paramyxoviridae. Human infections are caused by zoonotic events where the virus crosses over from another animal species. Therefore, humans are not the innate host for this virus family but instead become infected by peripheral viral reservoirs such as bats and other carriers of the virus. When these virus are spread to humans through zoonotic events they have been found to be one of the most deadly viruses with the capability to infect humans, with mortality rates between 50 and 100%. Therefore, these viruses have been classified as a biosafety level four (BSL-4) virus with regards to its pathogenesis when it infects humans. Compared to other henipaviruses, KV exhibits reduced surface expression of the attachment glycoprotein (KV-G). It is likely that KV-G expression is delayed in the endoplasmic reticulum and is not exported as readily to the cell surface due to defects in higher-order oligomerization. This may lead to reduced pathogenicity.
Emergence Emergence of Henipavirus was seen in 1994 when an outbreak in Australia caused an infectious outbreak in horses leading to severe respiratory disease. During this outbreak two people were infected and one died. Henipavirus emergence is still relatively recent leading to a need for a greater range of genomic studies. Upon emergence in Australia it was found that Australian mainland flying foxes (bats) were the primary reservoir for the virus through analysis of their uterine fluid and urine. However, it was discovered through subsequent break outs of Henipavirus that humans do not seem to contract the disease directly from flying foxes. In all human cases (4 of which have been fatal) the primary vector of transmission was infected horses. Therefore, it seems that horses contract the disease from flying foxes while humans contract the virus through close proximity to infected horses. This has also been further supported by a decrease in human contraction of Henipavirus after the development of an equestrian vaccine for the virus. Epidemiological data show the presence of these viruses in Asia, Africa, and the South Pacific. In several studies it has been shown that bats, livestock, and humans carry neutralizing antibodies for Henipavirus in the Ghanaian region showing the potential for the existence of the virus within this population. GhV was first detected in a zoological garden in Kumasi, Ghana in February 2008. Guano samples from a colony of an estimated 400,000 bats of the species Eidolon helvum were collected and screened for viral RNA. While 3 RNA genomes were obtained: BatPV/Eid.hel/GH10/2008; BatPV; Eid.hel/GH45/2008; and BatPV/Eid.hel/GH48/2008, only isolate BatPV/Eid.hel/GH10/2008 contained enough RNA to reliably quantified. BatPV/Eid.hel/GH10/2008 showed the highest sequence parsimony to established Nipah and Hendra henipavirus genomes. Infectious particles could not be isolated in cell culture; no cytopathic effects were observed and no viral RNA could be obtained. KV would be the first known henipavirus detected outside of the Austroasiatic geographic province that other known henipaviruses are known to circulate. Serological evidence has previously suggested that henipaviruses likely have a much wider geographic range beyond areas of endemic Nipah and Hendra infection, namely that undetected henipavirus infections may be common in South America and continental Africa.
Genome Henipavirus contain an enveloped single-strand negative-sense RNA genome. Therefore, they belong to the same genomic group of viruses such as measles and mumps which are more commonly found to cause pathogenesis and infection in humans; Measles, mumps, and other related viral pathogens also belong to the viral family Paramyxoviridae. There are two pathogenic members of the Henipavirus genome, Nipah Virus (NiV) and Hendra Virus (HeV). Ghanaian Bat Henipavirus (GhV) is phylogenetically related to both NiV and HeV although it is most closely associated with NiV. Both NiV and HeV consists of an 18.2kb genome encoding for six structural proteins; nucleoprotein (N), phosphoprotein (P), matrix protein (M), fusion protein (F), attachment glycoprotein (G), and the large protein or RNA polymerase protein (L). Furthermore, three nonstructural proteins are encoded by the P gene; Two RNA editing proteins (W and V) and on alternative open reading frame protein (C). These genomes are conserved in most phylogenetic members of the Henipavirus genus. While members of the Henipavirus genus are similar in structure and protein makeup they do have subtle genomic differentiation in their nucleic acid sequences. While subtle differences exist both HeV and NiV are replicable in a variety of host species such as its natural reservoir bats, several forms of livestock, and of course humans. However, the zoonotic potential for GhV is unknown as there have been no cases of transmission in Africa from the bat reservoir to any other organism.
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