Epidemiology and HIV’s Physical Properties

OCT.19 '95 7:35AM 310-446-1664 LAYNE @ UCLA. [phone] P.8
COMMENTARY
operations - labelling, pipetting, mixing, transferring, centrifuging, washing, incubating, image
analyzing and so forth - that are repeated in various orders, according to the assay type.
Automating all these operations is well within the scope of existing technologies23. For certain
applications, automation will require only the adaptation of conmnercial instruments but for others,
it will require the development of new systems over several years.
Governments and international agencies can play a central role in fostering this
interdisciplinary effort24. They can provide financial support for undertaking epidemiologic
surveys, conducting basic research on HIV's physical properties and developing automated
systems that increase human capacity. These same organizations can also help by establishing
advisory committees that plan, coordinate and prioritize.
Over the past three decades, HIV infections have risen from sporadic cases to a global
pandemic involving more than 18 million individuals. In 1994 alone, end-stage infections (AIDS)
killed nearly one million individuals, making it the world's seventh leading cause of death by an
infectious disease25. Even worse, all indicators suggest that AIDS deaths will continue to climb
this ranking (Table 1). An estimated 75% of the world's new infections are attributable to sexual
transmission and 10% to maternal-foetal transmission, making it imperative that we understand the
virologic factors influencing the pandemic.
A number of fundamental questions remain unanswered. Why is HIV-1 more transmissible
than HIV-2? Is the maturing epidemic generating more transmissible viruses? Do more
transmissible viruses emerge with disease progression? Do physical properties of the virus
correlate with disease progression? We are faced with an unprecedented situation regarding the
variability of HIV and the growing epidemic. Vaccine developers are pondering how to target the
"right" assortment of viruses. Beyond selecting the most prevalent viruses, knowledge of the
physical properties would enable them to identify the most formidable strains (based on the largest
infectious ratios, longest infectious stabilities or greatest reproductive numbers). Studying the
physical properties of HIV isolates could provide us with the information that we need to move
ahead- we should start now. O

Scott P. Layne is at the Department of Epidemiology, School of Public Health, University of California
Los Angeles, Los Angeles, California 90095-1772, USA.

7