Department of Veterinary Medicine

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Development of a Multilocus Sequence Typing Scheme for Avibacterium paragallinarum
(2023) Harris, Alyssa Meihua; Ghanem, Mostafa; Veterinary Medical Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Avibacterium paragallinarum (A. paragallinarum), the causative agent of the respiratory disease Infectious Coryza (IC) in chickens, has seen a rising incidence in the United States. Current strain differentiation is inadequate for detailed epidemiological analysis. The objective of this study was to develop a Multilocus sequence typing (MLST) scheme for A. paragallinarum for outbreak investigations and to offer a better tool for strain differentiation. By evaluating whole genome sequences and clinical samples, we designed PCR amplicons for eighteen gene segments, selected six genes for their nucleotide diversity and discrimination potential. The MLST was used to differentiate seventy-five samples. Our MLST showed greater discriminatory power than existing HPG2-based methods, aligning closely with adhoc core genome MLST in 75 tested sample. Our newly developed MLST scheme enables more accurate strain differentiation, allowing for better understanding of A. paragallinarum epidemiology and population structure to help prevention and control efforts worldwide.
Ecology and Molecular Epidemiology of Avian and Swine Influenza A viruses in Guatemala
(2015) Gonzalez Reiche, Ana Silvia; Perez, Daniel R.; Veterinary Medical Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
The greatest diversity of Influenza A viruses (IAV) is found in waterfowl species from numerous geographic locations. In addition, multiple IAV are, and continue to be, perpetuated in swine populations around the globe. Due to the zoonotic potential of IAV and to respond more effectively to potential agricultural and public health threats, there is a need to increase surveillance in avian and swine hosts in understudied geographical regions. In Latin America, avian influenza surveillance has been scarce, localized only to places where outbreaks in poultry have occurred. Similarly, active swine influenza surveillance was implemented only after the emergence of the 2009 pandemic strain (pH1N1). The project presented here was aimed at investigating the circulation of IAV in wild birds and pigs in Guatemala. Over 2200 birds were sampled during six consecutive migration seasons from 2007 to 2013 in different locations. Virus prevalence detected by rRT-PCR in positive species ranged from 5.2% to 38%. Preliminary data indicates temporal variation of IAV prevalence in migratory waterfowl. Eighty-three viruses were recovered with 22 different subtype combinations. Through phylogenetic inferences and the analysis of virus genotypes and gene constellations of 60 fully sequenced genomes, we provide a detailed description of the genetic structure of avian IAV circulating in Guatemala. Our results suggest that the virus diversity in this location is sourced from multiple migration flyways from North America. Overlap of these flyways, in a natural geographical bottleneck such as the Neotropics, may contribute to the patterns of extensive genetic reassortment observed at a continental scale. In addition, the results from two nationwide multistage random surveys in pigs demonstrated circulation of swine influenza in commercial and peridomestic herds in Guatemala. Herd prevalence of IAV was 36.3% in 2010 and 34.6% in 2011. Viruses of the H1N1 and H3N2 subtypes and antibodies against viruses of distinct genetic lineages of these subtypes were detected. Our results indicate that human-animal contact likely plays a role in the IAV epidemiology in local swine populations. The findings from this research constitute the most abundant data on the ecology and epidemiology of animal influenza currently available for Central America.
HEPATITIS E VIRUS MODULATES HOST FACTORS TO GENERATE A CONDUCIVE ENVIRONMENT FOR REPLICATION
(2020) lin, shaoli; Zhang, Yanjin; Veterinary Medical Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Hepatitis E virus (HEV) is one of the causative agents for liver inflammation across the world. HEV infection mainly presents as acute and self-limiting hepatitis in young adults. However, it can be exacerbated to fulminant hepatitis in HEV-infected pregnant women, resulting in up to 30% case fatality. Besides, chronic HEV infection with rapid progression in immunocompromised patients has been a challenge in many countries since it was reported years ago. HEV infection is zoonotic, and human HEV strains are grouped into four major genotypes in the genus Orthohepevirus A, the family Hepeviridae. Among the four genotypes, genotype 1 and 2 are obligate human pathogens, and genotype 3 and 4 cause zoonotic infections. Due to the lack of an effective cell culture system and a proper animal model, HEV biology, virus-cell interactions, and pathogenesis are understudied. HEV is known to inhibit the innate immune response by targeting type I interferon (IFN) signaling pathway via its ORF1 products. Nevertheless, it remains largely unknown how the virus manipulates host factors to facilitate its replication. The objective of these studies was to elucidate the mechanism of HEV manipulation of host factors to generate a conducive environment for replication. Our results show that the capsid protein of HEV inhibits the IFN production to dampen the antiviral response through its N-terminal arginine-rich motif. In addition to the impairment of innate immunity, HEV proliferation requires the presence of other host factors: DDX3, an RNA helicase, and oxysterol-binding protein (OSBP), a lipid transporter. The knockdown of these two factors led to a significant reduction of HEV replication, whereas the reconstitution of these two genes restores the HEV proliferation level. The capsid protein was found to interact with the C-terminal domain of DDX3. The HEV helicase was shown to interact with OSBP and block its translocation to the Golgi apparatus. These results indicate that HEV employs multiple strategies including blocking antiviral response and recruiting host factors for its invasion and proliferation. Our data provide insights into the HEV-cell interactions and may facilitate the development of novel antiviral strategies.
Review of the Molecular Biology and Epidemiology of Infectious Laryngotracheitis (Gallid Herpesvirus-1)
(2012) Menendez, Kimberly Rae; Tablante, Nathaniel L; Veterinary Medical Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
A review of the molecular biology and epidemiology of avian infectious laryngotracheitis (ILT) is conducted due to the outdated state of current ILT review material. The objective of this review is to include updated information on the molecular biology of Gallid herpesvirus 1 (GaHV-1), the causative agent of ILT, and to present the latest information on the molecular epidemiology of ILT. Recent developments in molecular biology specific to GaHV-1 have been made and are highlighted in this review, and the role of current and historical use of live-attenuated vaccines is associated with the global and molecular epidemiology of ILT. Also, target genes for detection and strain differentiation are compiled by region of the world, and the global distribution of ILT is illustrated. Additionally, the field of epigenetics related to virus-host interactions is reviewed, and the molecular, epidemiologic, and epigenetic factors investigated are related to prospects for future eradication of ILT.