Tips from the Journals of the American Society for Microbiology

02/17/05

New Coronavirus Identified in Bats

Chinese researchers have identified a novel coronavirus found in bats. Their findings appear in the February 2005 issue of the Journal of Virology.

Transmission of animal viruses to humans poses a growing threat worldwide. The recent emergence of SARS, a coronavirus transmitted to humans from wild animals in live animal markets, reinforces the need for virus surveillance in exotic wildlife.

Most coronaviruses are disease-causing agents associated with respiratory and gastrointestinal illness in humans and respiratory and neurological symptoms in animals. In the study respiratory and fecal samples were collected from twelve bat species of which three tested positive for the novel virus (Bat-CoV). All bats testing positive for the virus were healthy when physically examined so it remains unclear as to whether or not the virus is pathogenic in bats.

"Here, we report the identification of a novel bat coronavirus," say the researchers. "It is not known whether this virus would cause zoonotic disease in humans or other animals, but given the catastrophic consequences of SARS, further surveillance work on viruses in wildlife should be encouraged."

(L.L.M. Poon, D.K.W. Chu, K.H. Chan, O.K. Wong, T.M. Ellis, Y.H.C. Leung, S.K.P. Lau, P.C.Y. Woo, K.Y. Suen, K.Y. Yuen, Y. Guan, J.S.M. Peiris. 2005. Identification of a novel coronavirus in bats. Journal of Virology, 79. 4: 2001-2009.)

New Test May Differentiate Between Poultry Vaccinated Against or Infected with Avian Flu

A new diagnostic test monitoring antibody response to the NS1 virus protein may allow for differentiation between poultry vaccinated or infected with avian influenza say researchers from Georgia. Their findings appear in the February 2005 issue of the Journal of Clinical Microbiology.

Avian influenza (AI), a viral disease of poultry, causes a wide range of diseases affecting multiple organs and often resulting in death. In recent years, new strains of the virus have continued to emerge and cross over from the wild bird reservoir to domestic poultry.

"Over the last decade, AI viruses circulating in live-bird markets have provided a secondary reservoir from which influenza viruses have crossed over to infect commercial chicken and turkey operations," say the researchers.

A vaccine incorporating the inactivated whole-virus has been used in an attempt to prevent AI infection. While these traditional vaccines can protect against clinical infection and death, they can interfere with surveillance programs. Vaccination produces the same antibodies as an actual AI infection, and can commonly cause false positives with traditional diagnostic tests.

In the study, the researchers designated the NS1 virus protein, typically found in large amounts in virus-infected cells but not the virus itself, as a potential differential marker. They monitored both infected and vaccinated poultry for antibodies reactive to NS1. While live virus infection induced high levels of the NS1 antibody, commercial vaccines induced little or no antibody response.

"These results demonstrate the potential benefit of a simple, specific enzyme-linked immunosorbent assay (ELISA) for anti-NS1 antibodies that may have diagnostic value for the poultry industries," say the researchers.

(T.M. Tumpey, R. Alvarez, D.E. Swayne, D.L. Suarez. 2005. Diagnostic approach for differentiating infected from vaccinated poultry on the basis of antibodies to NS1, the nonstructural protein of influenza a virus. Journal of Clinical Microbiology, 43. 2: 676-683.)

Salmonella spp. Prevalent in Oysters in U.S. Waters

Oysters harvested from thirty-six bays around the United States showed high prevalence of Salmonella according to a report that appears in the February 2005 journal Applied and Environmental Microbiology.

Known carriers of viral and bacterial pathogens, seafood and shellfish accounted for 7.42% of food poisoning related deaths attributed to Salmonella between 1990 and 1998. Characterized by fever, abdominal cramps, and diarrhea, salmonellosis is responsible for approximately 500 deaths annually in the U.S. alone. Current guidelines require the shellfish industry to test for evidence of bacterial contamination, however previous studies indicate that Salmonella could be present in oysters appearing otherwise healthy, indicating the need for testing specific to Salmonella.

"There are no current requirements for U.S. states to test harvesting waters for the presence of human pathogens, such as Salmonella spp.," say the researchers.

In the study oysters were harvested from thirty-six U.S. bays, twelve from the West, East, and Gulf coasts during the summer of 2002 and four bays per coast in the winter of 2002, and tested for the presence of Salmonella. Results showed that 7.4% of the oysters tested were positive for Salmonella and they came from all three U.S. coasts.

"Potential pathogenic serotypes of Salmonella were isolated from oysters harvested on all three U.S. coasts," say the researchers. "The testing of the oyster meat specifically for Salmonella spp. on a regular basis throughout the year, in each bay open for harvesting, would appear to be the only mechanism to remedy this oversight."

(D.A. Brands, A.E. Inman, C.P. Gerba, C.J. Mare, S.J. Billington, L.A. Saif, J.F. Levine, L.A. Joens. 2005. Prevalence of Salmonella spp. in oysters in the United States. Applied and Environmental Microbiology, 71. 2: 893-897.)

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