Evaluation of the Gastrointestinal Tract as a Potential Route of Primary Polyomavirus Infection

G. Huang,¹ G. Zeng,² Y. Huang,² P. Randhawa.²

¹Department of Organ Transplantation, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
²Department of Pathology, University of Pittsburgh Medical Center, Pittsburgh, PA.

Meeting: 2015 American Transplant Congress

Abstract number: A22

Keywords: Infection, Mice, Polyma virus, Polymerase chain reaction (PCR)

Detection of Polyomavirus(Py) DNA in metropolitan river water worldwide has led to the suggestion that primary viral infection can occur by the oral route. The aim of this study was to test this notion experimentally and to compare this route of transmission with the more widely recognized respiratory route.

Mouse Py (MPyV) LID -1 strain was propagated in NIH 3T3 cells and 1×10⁹ genomic equivalents were used to infect 4 week old, 15-20 gram, male, C57BL/6J mice by the nasal or gastric route(n=24 in each group). The Qiagen DNeasy Blood & Tissue Kit was used to extract viral DNA from different organs. Viral load kinetics was studied in groups of 4 mice, sacrificed 3, 7, 10, 14, 21 and 28 days after infection. For quantitation of viral load, MPyV A2 large T antigen gene derived primers were used in a SyBrGreen based PCR run on the ABI Prism 7500 System using a MPyV-PYA3 plasmid based standard curve.

Following nasal infection MPyV DNA was readily detected at virtually all time points with a peak observed on day 10 (see table below).

Viral Load Following Nasal or Oral Infection

Organ		3 days post-infection	7 days post-infection	10 days post-infection	14 days post-infection	21 days post-infection	28 days post-infection
Kidney	Nasal	ND	1.3±0.5	2.2±1.4	1.0±2.9	-0.8±2.6	-2.0±2.0
	Oral	ND	ND	ND	-2.0±2.0	0.2±2.5	ND
Lung	Nasal	4.0±1.9	4.0±4.7	6.3±0.3	5.9±0.2	5.1±0.3	4.9±0.4
	Oral	ND	0.5± 2.4	-0.8± 2.5	-1.8±2.4	2.9±0.6	-1.0±2.4
Heart	Nasal	-2.1±1.8	-1.2±2.1	0.7±2.8	0.5±2.6	0.1±2.1	-0.6±3.0
	Oral	ND	ND	ND	-1.3±2.0	-1.2±2.1	ND

Data is expressed as log viral copy number per mg wet weight. Heart used as a surrogate for blood. ND= not detected In contrast oral infection resulted in no detectable virus or substantially lower viral loads that usually peaked close to day 21. MPyV DNA load at the time of the first detection and peak levels were higher after nasal compared to oral infection (p<0.05). Histopathologic examination did not show any viral cytopathic effect in the kidney, consistent with the two hit hypothesis for pathogenesis of PyV nephropathy.

It is concluded that the oral route of MPy infection is successful, not as efficacious as the respiratory route, and associated with delayed viral dissemination as well as a lower peak MPy load in individual organs.

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