The Informatics Crystal Ball: Mining the Past to Predict the Species Jump Event 19 April 2011 Richard H. Scheuermann, Ph.D. Department of Pathology U.T. Southwestern Medical Center

Flu pandemics of the 20 th and 21 st centuries initiated by species jump events 1918 flu pandemic (Spanish flu) – subtype H1N1 (avian origin) – estimated to have claimed between 2.5% to 5.0% of the world’s population (20 > 100 million deaths) Asian flu (1957 – 1958) – subtype H2N2 (avian origin) – million deaths Hong Kong flu (1968 – 1969) – subtype H3N2 (avian origin) – between 750,000 and 1 million deaths 2009 H1N1 – subtype H1N1 (swine origin) – ~ 16,000 deaths as of March 2010

Pandemic species jump

Pandemic stages Adaptive drivers

Basic reproductive number (R 0 ) Total number of secondary cases per case Reasonable surrogate of fitness Characteristics of pandemic viruses: – R 0 H >1, and – In genetic neighborhood of viruses with R 0 R>1 and R 0 H<1 Adaptive drivers Pandemic Viruses (R 0 H >1) Pandemic Viruses (R 0 H >1) Stuttering viruses (R 0 R>1 and R 0 H<1) Stuttering viruses (R 0 R>1 and R 0 H<1) Reservoir virus (R 0 R>1 and R 0 H<<1) Reservoir virus (R 0 R>1 and R 0 H<<1) A1A2

Adaptive drivers Pepin KM et al. (2010) “Identifying genetics markers of adaptation for surveillance of viral host jump” Nature Reviews Microbiology 8:

Stuttering transmission and adaptive drivers Stuttering transmission can reveal adaptive drivers by evidence of convergent evolution – Odds of finding the same neutral mutation by chance in multiple species jumps is low – Therefore, finding same mutation in multiple independent species jump events is strong evidence for adaptive driver

Genetic convergence during species jump Virus isolate groups from IRD – Avian H5N1 (PB2) from Southeast Asia* up to 2003 (260 records) – reservoirs of source viruses – Human H5N1 (PB2) from Southeast Asia 2003-present (165 records) – many examples of independent species jumps Align amino acid sequence and calculate conservation score Identify highly conserved positions in avian records (≤1/260 variants) (557positions/759) – functionally restricted in reservoir Select subset in which two or more human isolates contained the same sequence variant – either due to human-human transmission or convergent evolution *China, Hong Kong, Indonesia, Thailand, Viet Nam

Strain Search – PB2 avian H5N1 Southeast Asia up to 2003

260 PB2 records

Sequence variation analysis

Position order

Order by conservation score

My Workbench

Convergent evolution candidates d d d

Surface exposed PB2_A/MEXICO/INDRE4487/2009(H1N1) Conservation score All convergent evolution candidates 586, 591, 627, 629

Convergent evolution candidates

E627K

E627K and species jump

K660R

Summary Human influenza pandemics are initiated by species jump events followed by sustained human to human transmission (R 0 H>1) Multiple independent occurrences of the same mutation during stuttering transmission is evidence of convergent evolution of adaptive drivers – hypotheses for experimental testing Surveillance for adaptive drivers in reservoir species could help anticipate the next pandemic N01AI40041