Macaques infected with SIV and testes removed

Macaques infected with SIV and testes removed

Winnall, WR, Lloyd, SB, De Rose, R, Alcantara, S, Amarasena, TH, Hedger, MP, Girling, JE & Kent, SJ 2015, ‘Simian immunodeficiency virus infection and immune responses in the pig-tailed macaque testis’, Journal of Leukocyte Biology, 97.

Associated Institution(s): The University of Melbourne, Peter Doherty Institute for Infection and Immunity, Centre for Reproductive Health, Monash Institute of Medical Research-Prince Henry’s Institute of Medical Research, Royal Women’s Hospital, CSIRO

The Experiment

Eleven healthy young-adult pig tailed macaques (aged between 4 – 6 years) were housed at the Australian Animal Health Laboratory in Geelong, Victoria, and used in HIV research.

Four of the macaques were infected with simian immunodeficiency virus (SIV) infection by way of injection. An orchidectomy (removal of a testicle) was performed under sedation 10 – 11 weeks after infection was induced. The second testicle of these animals was removed at autopsy (24-30 weeks after infection).

The remaining seven uninfected macaques had their testis removed and used for comparison.

Conclusions drawn from their study include the fact that SIV does not lead to major inflammatory damage in the testis “of macaques”.

Relevance to Humans

In over thirty years of research into HIV there is still no cure and no vaccine for this preventable disease.”

– Jacqueline Cutherbertson(1)

The non-human primate (NHP) is the animal most often used for HIV research because of their similarity to humans. However, even our closest relative, the chimpanzee, does not develop AIDS. When artificially infected with HIV it has been found that monkeys have their own variety of HIV known as the simian immunodeficiency virus (SIV) and therefore researchers have studied the progression of this disease and tried to draw parallels between it and the human version. However, humans and primates have different infection processes, metabolisms, and therefore different responses to drugs. According to Kaufman all species differ in their immune and other systems, and even subtle differences among them can result in major consequences.(2) Further he states that humans are far more susceptible to HIV-1 than any other animal. This research by Winnall et al. is not only studying a different species but a different virus – the SIV virus.

Furthermore, it has been shown that over 90% of drug candidates fail during human trials and not one of the 80 drug candidates for a HIV vaccine has been successful(3).

Animal Welfare Concerns

Monkey species have rich social lives taking place in diverse groups and mixed habitats. Their behaviour is complex and varied. Their mental abilities are developed to the point that they can reflect on what is happening to them. Cuthbertson notes that any animal with a nervous system suffers from events such as removal from its own kind, fear, and being subjected to invasive and often painful tests with no knowledge of what is going to happen next (1).


This research was supported by Australian National Health and Medical Research Council (NHMRC) fellowships, NHMRC Program Grant 1052979 $ 12,826,658.25 Application Year: 2012 Start Year: 2014 End Year: 2018), and the Victorian government’s Operational Infrastructure Support Program.


(1) Cuthbertson, J 2012, ‘Primates and HIV Research – Infecting our closest relatives’. Available at:

(2) Kaufman, SC 2012, ‘Shortcomings of AIDS-related animal experimentation’, Medical Research Modernization Committee. See:

(3) Bailey, J 2005, ‘Non-human primates in medical research and drug development: a critical review’, Biogenic Amines, 19: 235-255.


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