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SIV infections in Central African villagers João Dinis de Sousa Laboratory for Clinical and Epidemiological Virology

I will concentrate on the following paper: Kalish, M.L.; Wolfe, N.D.; Ndongmo, C.B.; McNicholl, J.; Robbins, K.E.; Aidoo, M.; Fonjungo, P.N.; Alemnji, G.; Zeh, C.; Djoko, C.F.; et al. Central African hunters exposed to simian immunodeficiency virus. Emerg. Infect. Dis. 2005, 11, 1928–1930.

Rega Institute for Medical Research Katholieke Universiteit Leuven João Dinis de Sousa, February 2012

Lemey, 2005

HIVs cluster among SIVs

João Dinis de Sousa, February 2012

How humans acquire simian retroviruses

SIVcpz (from chimpanzee) gave rise to HIV-1 groups M and N

 Injuries suffered during hunting; these injuries are SIVgor (gorilla) gave rise to HIV-1 group P Either SIVcpz or SIVgor (gorilla) gave rise to HIV-1 group O

correlated with Simian Foamy Virus (SFV) infection among hunters  Butchering of bushmeat by hunters in loco, by cooks, or

by bushmeat traders -- exposure to simian blood SIVsmm (sooty mangabey monkey) gave rise to HIV-2 groups A , B, and E

 Scratches and bites from simians pets  Ingestion of undercooked meat

Epidemic HIVs (in red) are just an handful… João Dinis de Sousa, February 2012

Bushmeat and risk of retroviral zoonoses


Investigating SIV seroreactivity in Central African villagers  Peptide-based EIA assay  Capable of detecting antibodies against the Immunodominant Region (IDR) of gp41/gp36 and against the V3  Coverage of 11 different SIVs: SIVcpz, SIVcol, SIVmnd, SIVdrl, SIVrcm, SIVagm, SIVsmm, SIVsyk, SIVdeb, SIVlhoest, SIVsun, and HIVs  Screened >1,200 Cameroonian villagers (Kalish et al. (2005), Emerg Inf Dis 11:1928-30)



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Bushmeat hunters and handlers have unusually high SIV seroreactivity SIV seroreactivity in HIVseronegative Cameroonian population groups with different levels of exposure (high exposure [HE], low exposure [LE], or general [G]) to nonhuman primates. (Kalish et al, 2005).

This SIV seroreactivity was against IDR only in all but one person

Stronger reactions in 1 person only  In just one of the 42 persons showing reactions in the IDR peptides there was a corresponding reaction against V3 peptides  SIVcol (from Colobus guereza monkey, hunted frequently)  They still could not recover virus through PCR  They write: “Therefore, seroreactivity to SIVcol in this person may reflect exposure to nonviable or defective SIVcol, a nonproductive or cleared infection, or sequestering of virus in lymphatic tissues.”


The rare HIV-2 groups Country

People

Sequenced viruses

Others


An hierarchy of human SIV infections Examples

Source

Liberia

944 rubber workers, center 372 rurals, north

1 HIV-2 C, 1 HIV-2 D

5 additional HIV-2+, group unknown

Gao et al. 1992

Sierra Leone

9,309 rurals, north

1 HIV-2 F

1 HIV-2 A Many others HIV-2+ in EIA only

Chen et al. 1997

Ivory Coast

776 rurals, Tai forest

1 HIV-2 I

1 HIV-2 A, 1 HIV-2 B, 3 others HIV-2+, group unknown

Ayouba et al. 2012, CROI

Better adapted; Large epidemic

HIV-1 M, HIV-2 A, HIV-2 B Each >100k people infected

Capable of transmission; Small epidemics

HIV-1 N, HIV-1 P, HIV-2 E, HIV-2 H? Others? Each 10-200 people infected

Strong seroreactions; Virus un-/poorly adapted

HIV-2 C, D, F, G, I, others? SIVcol (Kalish)

Very limited seroreactions; Virus unadapted

Other cases in Kalish; 8-17% of villagers



Discussion Discussion Tens to hundreds of thousands of Central/West Africans may have SIV antibodies

How do SIVs “climb the pyramid”? Better adapted; Large epidemic

events? How?

Yet the virus is unadapted and unrecoverable in most

 Serial transmission?

Very few such infections turned into HIVs What’s going on here? João Dinis de Sousa, February 2012

 Successive adaptive

(sexual? parenteral?)  Epidemic luck? Very limited seroreactions; Virus unadapted

 Recombination?  “Just happens”? João Dinis de Sousa, February 2012

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Acknowledgments Anne-Mieke Vandamme Philippe Lemey Viktor Müller Nuno Faria Carolina Alvarez And all my colleagues in the Laboratory for Clinical and Epidemiological Virology, KU Leuven


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