Presentation 4: Origin and Evolution of Nipah Virus

Question 1

What were the objectives of this study?

Answer 1

Addressing origins and genetic diversity of NiV
Estimate date or origin of NiV
Identify possible causes and spread of specific NiV outbreaks
Elucidate genetic diversity and phylogenetic relationships among circulating strains

Question 2

What is NiV?

Answer 2

Animal to human or human to human transmission and a zoonotic disease

Question 3

Explain the NiV disease

Answer 3

Causes wide range of symptoms: asymptomatic, acute respiratory, GI infection, fatal encephalitis
No treatments or vaccine

Question 4

Explain the NiV genome

Answer 4

Paramyxoviridae family and Henipavirus genus
Negative sense ssRNA virus of 18 kb
Enveloped

Question 5

How was likelihood mapping done?

Answer 5

Tested 29 public gene sequences of N protein 
3 samples: 
Main dataset: 29%
Subset 1 : 23.3%
Subset 2: 28.6%
Analyzed 10,000 quartets

Question 6

How was phylogenetic analysis done?

Answer 6

Three separate models for population growth: 
Constant size 
Exponential: showed most significance 
Expansion 
Sequence alignment and goodness of fit 
Evolutionary rate and dating trees

Question 7

What was determined for evolutionary analysis?

Answer 7

Found no amino acids of positive selection, but 16 negative selection
Silent and non silent mutations are equally likely

Question 8

What were the main findings of this study?

Answer 8

Mean evolutionary substitution = 6.5e-4
Divergence of Bangladesh and Malaysian clades can be extrapolated to 1947
Bangladesh: went through Bangladesh, Thailand, and India
Malaysia: went through Cambodia and Thailand
Multiple possibilities for virus propagation
NiV are dead-end infections; no long term viral evolution contribution