Coding-Complete Genome Sequences of Emerging Rabbit Hemorrhagic Disease Virus Type 2 Isolates Detected in 2020 in the United States.

Five rabbit hemorrhagic disease virus type 2 (RHDV2) coding-complete genome sequences were obtained from the livers of domestic and wild rabbits during the 2020 outbreak in the United States. These represent the first available RHDV2 sequences from the United States.

Genome Sequences of Vesicular Stomatitis Indiana Viruses from the 2019 Outbreak in the Southwest United States.

We report the genomes of three vesicular stomatitis Indiana virus (VSIV) isolates collected from naturally infected bovines in Wyoming and Colorado during the 2019 outbreak in the United States. These genomes support molecular diagnostic efforts and provide data on the spread and ecology of VSIV in the United States.

Subcellular distribution of the foot-and-mouth disease virus 3A protein in cells infected with viruses encoding wild-type and bovine-attenuated forms of 3A.

Picornavirus infection induces the proliferation and rearrangement of intracellular membranes in response to the synthesis of nonstructural proteins, including 3A. We have previously shown that changes in 3A are associated with the inability of a Taiwanese strain of foot-and-mouth disease virus (FMDV) (OTai) to grow in bovine cells and cause disease in cattle, although the virus grows to high titers in porcine cells and is highly virulent in pigs (C. W. Beard and P. W. Mason, 2000, J. Virol. 74, 987-991). To study if differences in the distribution of 3A could account for the species specificity of OTai, we compared the localization of the OTai 3A with a bovine-virulent 3A (serotype A12) in keratinocytes prepared from the tongues of cattle and pigs. Following either infection of keratinocytes or transfection with 3A we were unable to discern differences in 3A distribution in either species of keratinocyte, independent of the strain of virus (or 3A) utilized. In both cell types, 3A distributed in a pattern that overlapped with an endoplasmic reticulum (ER) marker protein, calreticulin (CRT). Furthermore, although FMDV infection or transfection with 3A did not result in a gross redistribution of CRT, both virus infection and 3A transfection disrupted the Golgi. Other picornaviruses that disrupt Golgi function are sensitive to brefeldin A (BFA), a fungal metabolite that interferes with retrograde transport between the Golgi and the ER. Interestingly, BFA has little effect on FMDV replication, suggesting that FMDV may acquire cellular membranes into its replication complexes in a manner different from that of other picornaviruses.

Serological survey of viral antibodies in llamas (Lama glama) in Argentina.

This study analysed sera from 390 llamas (Lama glama) from nine farms located in three different Argentine provinces: Buenos Aires, Cordoba and Jujuy. The samples were tested for antibodies against 8 virus known to infect cattle: bovine herpesvirus type 1 (BHV-1), bovine viral diarrhea virus (BVDV), bovine adenovirus (BAdV III), bovine enterovirus (BEV), bovine rotavirus (BRV), bluetongue virus (BTV), bovine leukaemia virus (BLV), and foot-and-mouth virus (FMDV) by conventional methods such as seroneutralization, immunoperoxidase staining, and agar gel immunodiffusion. The antibody prevalences detected in llamas were: BHV-1 in 0.77% (3/390), BVDV in 2.05% (8/390), BAdV III in 5.13% (20/390), BEV in 4.10% (16/390), BRV in 87.69% (342/390). No antibodies against BTV, BLV and VIAA (FMDV infection associated antigen) were detected.

Detection of virus infection-associated antigen and 3D antibodies in cattle vaccinated against foot and mouth disease.

The analysis of sera obtained from animals vaccinated or revaccinated with inactivated vaccines against foot and mouth disease (FMD) virus showed that these vaccines induced antibodies against the virus infection-associated (VIA) antigen, detectable by agar gel immunodiffusion (AGID). The present study evaluates the antibody response to protein 3D and the VIA antigen (VIAA) of FMD virus induced by different vaccines in a group of 51 calves. This response was detected using AGID and a liquid-phase blocking sandwich enzyme-linked immunosorbent assay (ELISA) for anti-3D antibodies (ELISA-3D). No anti-VIAA or anti-3D antibodies were detected after the initial vaccination. Following revaccination, animals giving positive results were detected by both methods. This immune response disappeared 60-120 days post-revaccination (dprv) according to the AGID method, and 90-180 dprv when ELISA-3D was used. Samples of oesophageal-pharyngeal fluid obtained from animals that remained positive for anti-VIAA antibodies at 90-120 dprv gave negative results for viral isolation, indicating that the transitional antibody response induced by the vaccine was due to the presence of non-structural antigens in the vaccine and not to viral infection. These results indicate that the ELISA-3D method could be used as a complementary method for sero-epidemiological studies as an indirect indicator of viral activity, as long as the age and vaccination status of the animals being sampled are taken into consideration.

Detection of antibodies against foot-and-mouth disease virus using a liquid-phase blocking sandwich ELISA (LPBE) with a bioengineered 3D protein.

A liquid-phase blocking sandwich enzyme-linked immunosorbent assay (ELISA-3D) was developed to detect specific antibodies to the 3D protein in sera from foot-and-mouth disease (FMD) virus (FMDV)-infected animals. The assay uses a nonstructural 3D recombinant protein and two polyclonal antisera, one for capture (bovine) and the other for detector (guinea pig). The specificity of the assay was demonstrated by negative results with 101 sera of cattle from the FMD-free zone in Argentina and with bovine and porcine sera raised against various RNA and DNA viruses. The ELISA-3D was able to detect antibodies in cattle after natural or experimental infection with FMDV of A, O, or C types as early as 5 days postinfection and at later stages in persistently infected animals. Comparison of the results with those obtained with the routinely used agar gel immunodiffusion test and a previously described ELISA, both employing a partially purified virus-infection-associated antigen, shows that the ELISA-3D is highly sensitive and specific and gives reproducible results. Its use as a tool for monitoring viral activity and for certification of FMDV-free animals is recommended.

Susceptibility of llamas (Lama glama) to infection with foot-and-mouth-disease virus.

An experimental trial was conducted to evaluate the ability of foot-and-mouth-disease (FMD) virus (serotypes A79, C3, O1) to infect susceptible llamas exposed either directly to affected livestock, or indirectly to llamas that had been directly exposed to affected livestock. In addition, susceptible livestock species (cattle, pigs, goats, and sheep) were exposed to those llamas that had been both directly and indirectly exposed to the FMD virus to further look at potential transmission possibilities. Of 30 llamas directly exposed to the FMD virus, only three (3/30) showed evidence of infection, and of those, only two (2/30) had mild clinical signs. No FMD virus was isolated from either oesophageal-pharyngeal (OP) fluid or blood samples collected from the infected llamas beyond 14 days post-exposure. There was no evidence of virus transmission between the directly exposed and indirectly exposed llamas or between both groups of llamas and susceptible domestic livestock, as determined by the lack of clinical signs, by virus isolation, and by serology results. These results provide further evidence that llamas are resistant to FMD infection, and that they play a minor role, if any, in transmitting the virus to domestic livestock.