From Mosquitos to Humans: Genetic Evolution of Zika Virus - April 2016

[sharon sanders]

From Mosquitos to Humans: Genetic Evolution of Zika Virus

Lulan Wang10
, Stephanie G. Valderramos10
, Aiping Wu
, Songying Ouyang
, Chunfeng Li
, Patricia Brasil
, Myrna Bonaldo
, Thomas Coates
, Karin Nielsen-Saines
, Taijiao Jiang

, Roghiyh Aliyari

, Genhong Cheng

snip

Our phylogenetic analysis has revealed numerous sequence variations in ZIKV genomes between the African and Asian lineages, as well as among different strains within Asian lineage, as the clinical disease caused by ZIKV has changed from causing only a benign illness to now including severe neuropathology. Our modeling studies suggest that these sequence mvariations could mediate specific changes in the prM protein, which could play a role in virulence or improved fitness. In addition, we have narrowed these changes to a reasonable number of amino acid or nucleotide changes that can be tested for their effect on ZIKV infectivity. Future experiments will be required to determine which amino acid or nucleotide substitutions are directly responsible for the possible increased neurotropism, heightened viral fitness, and enhanced transmissibility and infectivity from the mosquito vector to the human host.


http://www.cell.com/cell-host-microb...128(16)30142-1

 

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More from this article:

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Due to the recent epidemic and technological advances that now allow rapid and full-length sequencing from direct human isolates, the public bank of human ZIKV sequences has increased from eight at the end of 2014 to 30 as of March 2016. We performed a detailed exploration of the evolution of amino acid polymorphisms of the recent human strains, all of the Asian lineage. Our phylogenetic analysis revealed that all contemporary human isolates share a common ancestor with the P6-740 strain isolated from Aedes aegypti mosquito. Comparison of protein sequences using P6-740 as the Asian reference showed that FSM had over 400 variations at the nucleotide level and 26 unique substitutions at the protein level (Figure 2B). Interestingly, when we investigated the sequences of selected human strains identified in more recent epidemics (including FSM, H/PF/2013, and Brazilian strains), we found that all of these strains have acquired changes at an additional eight positions, for a total of 34 amino acid changes compared to P6-740 (Figure 2B). Furthermore, all isolates show identical amino acids at these positions, with the exception of position T2634M/V in the NS5 protein.

Although ZIKV is believed to be primarily transmitted through the mosquito vector, it is interesting to note that no known ZIKV mosquito isolate possesses the same nucleotide sequence as the human strains. One possible explanation is sampling bias, where more recent efforts have focused on isolating the virus from infected humans rather than mosquito arbovirus surveillance. However, it is notable that Duffy et al. were unable to detect ZIKV in mosquitos despite active surveillance during the Micronesia outbreak (Duffy et al., 2009). Alternatively, it is possible that other routes of transmission, such as sexual transmission, may have a greater contribution to the wide spread of ZIKV in the Americas. Intriguingly, it was recently reported that New World strains of Aedes aegypti and albopictus are poor transmitters of ZIKV (Chouin-Carneiro et al., 2016). Clearly, more studies are urgently needed on natural vector transmission of ZIKV in Asia and the Americas, as well as the possibility of a more prominent contribution of alternative modes of transmission.
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[Pathfinder]

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Intriguingly, it was recently reported that New World strains of Aedes aegypti and albopictus are poor transmitters of ZIKV (Chouin-Carneiro et al., 2016). Clearly, more studies are urgently needed on natural vector transmission of ZIKV in Asia and the Americas, as well as the possibility of a more prominent contribution of alternative modes of transmission.[/B]
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Study: Differential Susceptibilities of Aedes aegypti and Aedes albopictus from the Americas to Zika Virus

Conclusions/Significance

This study suggests that although susceptible to infection, Ae. aegypti and Ae. albopictuswere unexpectedly low competent vectors for ZIKV. This may suggest that other factors such as the large na?ve population for ZIKV and the high densities of human-biting mosquitoes contribute to the rapid spread of ZIKV during the current outbreak.

https://flutrackers.com/forum/forum...es-albopictus-from-the-americas-to-zika-virus