Meat Exudate for Detection of African Swine Fever Virus Genomic Material and Anti-ASFV Antibodies.

Aruna Ambagala,Chukwunonso Onyilagha,Mikyla Nash,Orlando Perez,Juergen A. Richt,Alfonso Clavijo,Melissa Goolia

doi:10.3390/v13091744

Abstract

African swine fever (ASF) is one of the most important viral diseases of pigs caused by the ASF virus (ASFV). The virus is highly stable over a wide range of temperatures and pH and can survive in meat and meat products for several months, leading to long-distance transmission of ASF. Whole blood, serum, and organs from infected pigs are used routinely as approved sample types in the laboratory diagnosis of ASF. However, these sample types may not always be available. Here, we investigated meat exudate as an alternative sample type for the detection of ASFV-specific nucleic acids and antibodies. Pigs were infected with various ASFV strains: the highly virulent ASFV Malawi LIL 18/2 strain, the moderately-virulent ASFV Estonia 2014 strain, or the low-virulent ASFV OURT/88/3 strain. The animals were euthanized on different days post-infection (dpi), and meat exudates were collected and tested for the presence of ASFV-specific nucleic acids and antibodies. Animals infected with the ASFV Malawi LIL 18/2 developed severe clinical signs and succumbed to the infection within seven dpi, while pigs infected with ASFV Estonia 2014 also developed clinical signs but survived longer, with a few animals seroconverting before succumbing to the ASFV infection or being euthanized as they reached humane endpoints. Pigs infected with ASFV OURT/88/3 developed transient fever and seroconverted without mortality. ASFV genomic material was detected in meat exudate from pigs infected with ASFV Malawi LIL 18/2 and ASFV Estonia 2014 at the onset of viremia but at a lower amount when compared to the corresponding whole blood samples. Low levels of ASFV genomic material were detected in the whole blood of ASFV OURT/88/3-infected pigs, and no ASFV genomic material was detected in the meat exudate of these animals. Anti-ASFV antibodies were detected in the serum and meat exudate derived from ASFV OURT/88/3-infected pigs and in some of the samples derived from the ASFV Estonia 2014-infected pigs. These results indicate that ASFV genomic material and anti-ASFV antibodies can be detected in meat exudate, indicating that this sample can be used as an alternative sample type for ASF surveillance when routine sample types are unavailable or are not easily accessible.

Highlights

African swine fever is a highly fatal viral disease of pigs [1]
Pigs infected with ASF virus (ASFV) Malawi LIL 18/2 and ASFV Estonia 2014 developed fever starting from 3 dpi (Figure 1A,B)
The pigs infected with low virulent ASFV OURT/88/3 did not develop any clinical signs including fever after the primary infection (Figure 1C); on 14 dpi, when they were reinfected with a 10 times higher dose of ASFV OURT/88/3, a few pigs transiently developed a mild fever but quickly recovered within a few days (Figure 1C); no other clinical signs were observed in the ASFV OURT/88/3-infected pigs

Summary

Introduction

African swine fever is a highly fatal viral disease of pigs [1]. It is a World Organization for Animal Health (OIE) notifiable disease, which significantly impacts the local and international trade of live swine and pork products. Called “meat juice”, “purge,” “weep”, or “drip”, is one of the alternative sample types proven viable for determining the health status of pig herds [28,29,30,31]; it can be used for the detection of a number of viral, protozoal, and bacterial pathogens of pigs. It is often mistaken for blood, but the red color of meat exudate is based on myoglobin, not hemoglobin. Pigs were infected with high, moderatelyhigh, and low virulent strains of ASFV, and the meat exudate was collected and tested for the presence of ASFV-specific genomic material and antibodies

Ethics Statement

Pigs and Viruses

Inoculation and Sample Collection

Statistics

Results and Discussion

Malawi

TCID material

28.9 The meat