Infl uenza V irus Infect ion in Nonhuman Primates

Worldwide, infections with infl uenza A viruses are associated with substantial illness and death among mammals and birds. Public health and research have placed major focus on understanding the pathogenicity of different infl uenza virus strains and characterizing new infl uenza vaccines. Nonhuman primates (NHPs), including macaques, have become popular experimental models for studying the pathogenesis and immunology of seasonal and emerging infl uenza viruses. NHPs readily seroconvert after experimental inoculation with seasonal infl uenza virus and have been used to test candidate vaccines for strains of human and avian origin. Like humans, macaques infected with infl uenza virus exhibit fever, malaise, nasal discharge, and nonproductive cough; virus replication can be detected in the nasal passages and respiratory tract (1,2). However, whether NHPs are infected with infl uenza viruses in nature remains unknown. Over the past decade, we have focused on the role of pet and performing monkeys in disease transmission throughout Asia. Commonly trapped in the wild, these monkeys might be sold at wet markets, the putative source of several zoonotic outbreaks (3), where they might be caged next to any number of animal species (Figure 1, panel A) (4). Pet and performing monkeys are likely conduits for cross-species transmission of respiratory pathogens like infl uenza viruses because of their close and long-term contact with their owners, audiences, domestic animals, wild animals, and birds (Figure 1, panel B) (5). However, the breadth and diversity of this interface presents a challenge for monitoring the emergence of infectious diseases. We have approached this challenge by conducting longitudinal studies at several sites and collecting biological samples and behavioral data representing various contexts of human–NHP contact (4–7). We used these historical and newly acquired samples, representing various countries and contexts of human–macaque contact, to determine whether NHPs are infected with infl uenza viruses in nature.