The aim of the work presented here is to study the effectiveness of building air handling units (AHUs) in serving as high volume sampling devices for airborne bacteria and viruses. An HVAC test facility constructed according to ASHRAE Standard 52.2-1999 was used for the controlled loading of HVAC filter media with aerosolized bacteria and virus. Nonpathogenic Bacillus subtilis var. niger was chosen as a surrogate for Bacillus anthracis. Three animal viruses; transmissible gastroenteritis virus (TGEV), avian pneumovirus (APV), and fowlpox virus were chosen as surrogates for three human viruses; SARS coronavirus, respiratory syncytial virus, and smallpox virus; respectively. These bacteria and viruses were nebulized in separate tests and injected into the test duct of the test facility upstream of a MERV 14 filter. SKC Biosamplers upstream and downstream of the test filter served as reference samplers. The collection efficiency of the filter media was calculated to be 96.5 +/- 1.5% for B. subtilis, however no collection efficiency was measured for the viruses as no live virus was ever recovered from the downstream samplers. Filter samples were cut from the test filter and eluted by hand-shaking. An extraction efficiency of 105 +/- 19% was calculated for B. subtilis. The viruses were extracted at much lower efficiencies (0.7-20%). Our results indicate that the airborne concentration of spore-forming bacteria in building AHUs may be determined by analyzing the material collected on HVAC filter media, however culture-based analytical techniques are impractical for virus recovery. Molecular-based identification techniques such as PCR could be used.

Background culturable bacteria aerosols were collected and identified in two large public buildings located in Minneapolis, Minnesota and Seattle, Washington over a period of 5 months and 3 months, respectively. The installed particulate air filters in the ventilation systems were used as the aerosol sampling devices at each location. Both pre and final filters were collected from four air handing units at each site to determine the influence of location within the building, time of year, geographical location and difference between indoor and outdoor air. Sections of each loaded filter were eluted with 10 ml of phosphate buffered saline (PBS). The resulting solutions were cultured on blood agar plates and incubated for 24 h at 36 degrees C. Various types of growth media were then used for subculturing, followed by categorization using a BioLog MicroStation (Biolog, Hayward, CA, USA) and manual observation. Environmental parameters were gathered near each filter by the embedded on-site environmental monitoring systems to determine the effect of temperature, humidity and air flow. Thirty nine different species of bacteria were identified, 17 found only in Minneapolis and 5 only in Seattle. The hardy spore-forming genus Bacillus was the most commonly identified and showed the highest concentrations. A significant decrease in the number of species and their concentration occurred in the Minneapolis air handling unit supplying 100% outdoor air in winter, however no significant correlations between bacteria concentration and environmental parameters were found.

These findings indicate that existing building HVAC filters may be used as a method of detection for airborne viruses. As integrated long-term bioaerosol sampling devices, they may yield valuable information on the epidemiology and aerobiology of viruses in air that can inform the development of methods to prevent airborne transmission of viruses and possible deterrents against the spread of bioterrorism agents.

Heating, ventilating, and air-conditioning (HVAC) filters have the potential to serve as long-term integrated samplers for biological particles that may be released intentionally or unintentionally into a public building. Methods for eluting bacteria that are surrogates for potential bioterrorism agents from HVAC filters were tested for their ability to recover as high a percentage of culturable bacteria as possible. A solution of 0.02% Tween-80 in water was an effective eluent for Bacillus globigii (BG) spores whereas phosphate-buffered saline was the most effective eluent for vegetative bacteria. Hand shaking was a more effective agitation method for high recovery rates than vortexing or mechanical shaking. The results indicate that BG spores can be eluted successfully while maintaining essentially 100% culturability. The recovery of the vegetative bacteria Mannheimia haemolytica and Yersinia ruckeri was 80% or higher under optimal conditions. The culturability of the vegetative bacteria eluted from HVAC filters declined substantially within as little as 2 h after the bacteria were loaded onto the filter. The culturability of the BG spores eluted from filters exhibited an exponential decay subsequent to loading with a half-life of 8 -9 days.

Leukemia is characterized by the production of an excessive number of abnormal white blood cells. Over time, this expanding population of poorly/non- functional white blood cells overwhelms the normal function of the body's blood and immune systems. DNA translocations have been found common to leukemia, including Raf mutations. While the cause of leukemia is not known, several risk factors have been identified. In this review, we present an update on the role of AIDS related viruses as an etiology for leukemia. Human immunodeficiency virus-1 and -2 (HIV-1; -2) are the cause for the development of acquired immune deficiency syndrome (AIDS). Epstein-Barr virus (EBV), human cytomegalovirus (HCMV), Human papillomavirus (HPV), and Kaposi's sarcoma-associated herpesvirus (KSHV) are specifically implicated in AIDS associated malignancies. However, there are other viruses that are associated to a lesser extent with the AIDS condition and they are Human T-cell leukemia virus-1 (HTLV-1), hepatitis B virus (HBV), hepatitis C virus (HCV), and human herpesvirus-6 (HHV-6). Of these viruses, HTLV-1 has been etiologically associated with leukemia. Recent evidence suggests that EBV, HBV, HCV, and KSHV may also play a role in the development of some types of leukemia. Raf signaling has been shown to aid in the infection and pathogenesis of many of these viruses, making Raf pathway components good potential targets for the treatment of leukemia induced by AIDS related viruses.