From Foot-and-mouth Disease Research Articles

MILK PRODUCTION AND BUSINESS ANALYSIS ON DAIRY CATTLE AFFECTED BY PMK IN “KAMPOENG TERNAK” SIDOARJO LIVESTOCK: A LITERATURE REVIEW

mineral superboosters and concentrating immunoboosters in the feed. This research was conducted on the smallholder dairy cattle in "Kampoeng Ternak," Taman District, Sidoarjo, for 42 days. The material used was 18 Friesian Holstein (FH) dairy cattle suffering from FMD and decreased milk production. This research was carried out experimentally with three treatments: P0 (treatment injected multivitamins 10 ml + antibiotic long-acting 20 ml), P1 (treatment injected multivitamins 10 ml + antibiotic long-acting 20 ml and mineral super booster 40 grams), and P2 (10 ml treatment injected multivitamins + 20 ml long-acting antibiotics, adding 40-gram mineral super booster and 800-gram concentrate immunobooster). The data collected in this study is feed consumption, milk production, and profit analysis of business in the farm. The data were calculated and analyzed using anova. This literature review aims to describe adding mineral supplements to FH dairy cattle suffering from foot and mouth disease (FMD) as an alternative because it can increase milk production.

Characterization of Senecavirus A Isolates Collected From the Environment of U.S. Sow Slaughter Plants.

Vesicular disease caused by Senecavirus A (SVA) is clinically indistinguishable from foot-and-mouth disease (FMD) and other vesicular diseases of swine. When a vesicle is observed in FMD-free countries, a costly and time-consuming foreign animal disease investigation (FADI) is performed to rule out FMD. Recently, there has been an increase in the number of FADIs and SVA positive samples at slaughter plants in the U.S. The objectives of this investigation were to: (1) describe the environmental burden of SVA in sow slaughter plants; (2) determine whether there was a correlation between PCR diagnostics, virus isolation (VI), and swine bioassay results; and (3) phylogenetically characterize the genetic diversity of contemporary SVA isolates. Environmental swabs were collected from three sow slaughter plants (Plants 1-3) and one market-weight slaughter plant (Plant 4) between June to December 2020. Of the 426 samples taken from Plants 1-3, 304 samples were PCR positive and 107 were VI positive. There was no detection of SVA by PCR or VI at Plant 4. SVA positive samples were most frequently found in the summer (78.3% June-September, vs. 59.4% October-December), with a peak at 85% in August. Eighteen PCR positive environmental samples with a range of Ct values were selected for a swine bioassay: a single sample infected piglets (n = 2). A random subset of the PCR positive samples was sequenced; and phylogenetic analysis demonstrated co-circulation and divergence of two genetically distinct groups of SVA. These data demonstrate that SVA was frequently found in the environment of sow slaughter plants, but environmental persistence and diagnostic detection was not indicative of whether a sampled was infectious to swine. Consequently, a more detailed understanding of the epidemiology of SVA and its environmental persistence in the marketing chain is necessary to reduce the number of FADIs and aide in the development of control measures to reduce the spread of SVA.

Seneca Valley Virus 3C Protease Inhibits Stress Granule Formation by Disrupting eIF4GI-G3BP1 Interaction.

Stress granules (SGs) are the sites of mRNA storage and related to the regulation of mRNA translation, which are dynamic structures in response to various environmental stresses and viral infections. Seneca Valley virus (SVV), an oncolytic RNA virus belonging to Picornaviridae family, can cause vesicular disease (VD) indistinguished from foot-and-mouth disease (FMD) and other pig VDs. In this study, we found that SVV induced SG formation in the early stage of infection in a PKR-eIF2α dependent manner, as demonstrated by the recruitment of marker proteins of G3BP1 and eIF4GI. Surprisingly, we found that downregulating SG marker proteins TIA1 or G3BP1, or expressing an eIF2α non-phosphorylatable mutant inhibited SG formation, but this inhibition of transient SG formation had no significant effect on SVV propagation. Depletion of G3BP1 significantly attenuated the activation of NF-κB signaling pathway. In addition, we found that SVV inhibited SG formation at the late stage of infection and 3C protease was essential for the inhibition depending on its enzyme activity. Furthermore, we also found that 3C protease blocked the SG formation by disrupting eIF4GI-G3BP1 interaction. Overall, our results demonstrate that SVV induces transient SG formation in an eIF2α phosphorylation and PKR-dependent manner, and that 3C protease inhibits SG formation by interfering eIF4GI-G3BP1 interaction.

A Novel Live Attenuated Vaccine Candidate Protects Against Heterologous Senecavirus A Challenge.

Senecavirus A (SVA) is an emerging picornavirus causing vesicular disease (VD) clinically indistinguishable from foot-and-mouth disease (FMD) in pigs. Currently there are no vaccines currently available for SVA. Here we developed a recombinant SVA strain (rSVAm SacII) using reverse genetics and assessed its immunogenicity and protective efficacy in pigs. In vivo characterization of the rSVAm SacII strain demonstrated that the virus is attenuated, as evidenced by absence of lesions, decreased viremia and virus shedding in inoculated animals. Notably, while attenuated, rSVA mSacII virus retained its immunogenicity as high neutralizing antibody (NA) responses were detected in inoculated animals. To assess the immunogenicity and protective efficacy of rSVA mSacII, 4-week-old piglets were sham-immunized or immunized with inactivated or live rSVA mSacII virus-based formulations. A single immunization with live rSVA mSacII virus via the intramuscular (IM) and intranasal (IN) routes resulted in robust NA responses with antibodies being detected between days 3–7 pi. Neutralizing antibody responses in animals immunized with the inactivated virus via the IM route were delayed and only detected after a booster on day 21 pi. Immunization with live virus resulted in recall T cell proliferation (CD4+, CD8+, and CD4+/CD8+ T cells), demonstrating efficient stimulation of cellular immunity. Notably, a single dose of the live attenuated vaccine candidate resulted in protection against heterologous SVA challenge, as demonstrated by absence of overt disease and reduced viremia, virus shedding and viral load in tissues. The live attenuated vaccine candidate developed here represents a promising alternative to prevent and control SVA in swine.

Senecavirus A 3C Protease Mediates Host Cell Apoptosis Late in Infection.

Senecavirus A (SVA), an oncolytic picornavirus used for cancer treatment in humans, has recently emerged as a vesicular disease (VD)-causing agent in swine worldwide. Notably, SVA-induced VD is indistinguishable from foot-and-mouth disease (FMD) and other high-consequence VDs of pigs. Here we investigated the role of apoptosis on infection and replication of SVA. Given the critical role of the nuclear factor-kappa B (NF-κB) signaling pathway on modulation of cell death, we first assessed activation of NF-κB during SVA infection. Results here show that while early during infection SVA induces activation of NF-κB, as evidenced by nuclear translocation of NF-κB-p65 and NF-κB-mediated transcription, late in infection a cleaved product corresponding to the C-terminus of NF-κB-p65 is detected in infected cells, resulting in lower NF-κB transcriptional activity. Additionally, we assessed the potential role of SVA 3C protease (3Cpro) in SVA-induced host-cell apoptosis and cleavage of NF-κB-p65. Transient expression of SVA 3Cpro was associated with cleavage of NF-κB-p65 and Poly (ADP-ribose) polymerase (PARP), suggesting its involvement in virus-induced apoptosis. Most importantly, we showed that while cleavage of NF-κB-p65 is secondary to caspase activation, the proteolytic activity of SVA 3Cpro is essential for induction of apoptosis. Experiments using the pan-caspase inhibitor Z-VAD-FMK confirmed the relevance of late apoptosis for SVA infection, indicating that SVA induces apoptosis, presumably, as a mechanism to facilitate virus release and/or spread from infected cells. Together, these results suggest an important role of apoptosis for SVA infection biology.

Risk factors associated with clinical signs of vesicular stomatitis and seroconversion without clinical disease in Colorado horses during the 2014 outbreak

Vesicular stomatitis (VS) is caused by a contagious rhabdovirus that affects horses, cattle, and swine. Clinical signs of vesicular stomatitis virus (VSV) infection in pigs and cattle are indistinguishable from foot-and-mouth disease (FMD), a foreign animal disease and reportable disease in the United States (Rodriguez et al., 2000). A VS epidemic occurred in the Rocky Mountain region in 2014–15. A study was conducted in Colorado to evaluate horse- and management-level factors associated with VS. For a horse to be considered a clinical VS horse, there were two requirements. First, clinical VS horses had to have clinical signs consistent with VS, including one or more of the following: vesicles, ulcers, erosions or crusting on the muzzle, nares, lips, oral or nasal mucosa, ears, ventrum, udder or penile sheath, or coronary band lesions. Second, clinical VS horses had to have laboratory confirmation of VSV exposure via virus isolation from lesions or a positive complement fixation test performed on sera. All non-clinical horses residing on VSV-affected premises enrolled in the study were evaluated for exposure (i.e., seroconversion) to VSV. Overall, management and housing data were collected from 334 horses on 48 premises in Colorado. Approximately one-third (31.4%) of enrolled horses were clinical cases and two-thirds (68.6%) were controls. Three premises-matched logistic regression models were constructed in SAS using backward elimination (P-value < 0.05) after univariate screening of a priori-selected variables (P-value < 0.20). Model outcomes included differences in characteristics and management of 1) clinical and nonclinical horses, 2) exposed and unexposed horses, and 3) exposed nonclinical and unexposed nonclinical horses. Overall, factors most strongly associated with risk of being a VS clinical horse were access to pasture (P-value = 0.002), and pregnancy status (P-value = 0.001). Factors most strongly associated with VSV exposure among horses were access to pasture (P-value = 0.003) and lack of any insect control (P-value = 0.001). The only factor associated with VSV-exposed nonclinical horses compared with unexposed VSV horses was contact with clinical horses (P-value = 0.013). There were no associations identified regarding clinical horses compared with exposed nonclinical horses. With regard to severity of lesions (severe vs. moderate or mild), no variables met the criteria for inclusion in the multivariable model. Results of this study provide evidence that pasture access and fly control are important factors associated with VSV exposure.

Adaptive Immune Responses following Senecavirus A Infection in Pigs

Senecavirus A (SVA), an emerging picornavirus of swine, causes vesicular disease (VD) that is clinically indistinguishable from foot-and-mouth disease (FMD) in pigs. Many aspects of SVA interactions with the host and the host immune responses to infection, however, remain unknown. In the present study, humoral and cellular immune responses to SVA were evaluated following infection in pigs. We show that SVA infection elicited an early and robust virus-neutralizing (VN) antibody response, which coincided and was strongly correlated with VP2- and VP3-specific IgM responses. Notably, the neutralizing antibody (NA) responses paralleled the reduction of viremia and resolution of the disease. Analysis of the major porcine T-cell subsets revealed that during the acute/clinical phase of SVA infection (14 days postinfection [p.i.]), T-cell responses were characterized by an increased frequency of αβ T cells, especially CD4+ T cells, which were first detected by day 7 p.i. and increased in frequency until day 14 p.i. Additionally, the frequency of CD8+ and double-positive CD4+ CD8+ T cells (effector/memory T cells) expressing interferon gamma (IFN-γ) or proliferating in response to SVA antigen stimulation increased after day 10 p.i. Results presented here show that SVA elicits B- and T-cell activation early upon infection, with IgM antibody levels being correlated with early neutralizing activity against the virus and peak B- and T-cell responses paralleling clinical resolution of the disease. The work provides important insights into the immunological events that follow SVA infection in the natural host.IMPORTANCE Senecavirus A (SVA) has recently emerged in swine, causing outbreaks of vesicular disease (VD) in major swine-producing countries around the world, including the United States, Brazil, China, Thailand, and Colombia. Notably, SVA-induced disease is clinically indistinguishable from other high-consequence VDs of swine, such as FMD, swine vesicular disease, vesicular stomatitis, and vesicular exanthema of swine. Despite the clinical relevance of SVA-induced VD, many aspects of the virus infection biology remain unknown. Here, we assessed host immune responses to SVA infection. The results show that SVA infection elicits early B- and T-cell responses, with the levels of VN antibody and CD4+ T-cell responses paralleling the reduction of viremia and resolution of the disease. SVA-specific CD8+ T cells are detected later during infection. A better understanding of SVA interactions with the host immune system may allow the design and implementation of improved control strategies for this important pathogen of swine.

EVALUATION OF CLINICAL RECOVERY AND HEALING OF ORAL LESIONS BY 3 DIFFERENT THERAPEUTIC REGIMENS IN CATTLE WITH FOOT AND MOUTH DISEASE (FMD)

The study compares the clinical outcome of the use of different topical treatments for oral lesions in cattle suffering from foot and mouth disease (FMD). One hundred diseased cattle, during an outbreak of FMD in Assiut governorate, Egypt, were used in this study. The animals divided into four equal groups. The oral lesions after being washed with physiological saline solution to remove necrotic tissues, were sprayed twice daily by Phenytoin (PHEN group), Bacitracin and Neomycin (BAC-NEO group), Oxytetracycline and Crystal violet (OXY-CRY group), and the lesions leaved without any topical applications (control group). All animals in the four groups treated daily and for 3 consecutive days by the intramuscular injection of both Oxytetracycline as a broad spectrum antibiotics and Flunixin meglumine as antipyretic and anti-inflammatory drugs. It was observed that all animals in PHEN group show complete healing of oral lesions and the animals return to its normal appetite after 4 days whereas animals in BAC-NEO and OXY-CRY groups take a longer time to show improvement. The lesions in control group remain unhealed with bad appetite till the end of the observation period. It is concluded that Phenytoin (Healosol®) has a potent wound healing activity comparable to Bacitracin-Neomycin (Bivatracin®) and Oxytetracycline-Crystal violet (Oxy G®) in treatment of the oral lesions of FMD in cattle.

Qualitative Assessment of the Commodity Risk for Spread of Foot-and-Mouth Disease Associated with International Trade in Deboned Beef

The risk of importing foot-and-mouth disease virus (FMDV) restricts trade in livestock and their products from parts of the world where the virus is present. This reduces trade opportunities and investment in the livestock sector of many developing countries and constrains global food supply. This review focuses on the risks associated with trade in deboned beef (DB) from foot-and-mouth disease (FMD)-infected cattle, countries or zones. A definition of DB is provided along with a description of the procedures for its preparation within beef slaughtering operations. Evidence is reviewed for circumstances under which DB can be contaminated with FMDV, and a commodity risk factor approach is used to consider the mitigating efficacy of slaughterhouse procedures. A combination of pre-slaughter and slaughterhouse measures has enabled DB to be safely imported into FMD-free countries from countries that were not nationally or zonally FMD-free. Nevertheless, current evidence does not provide absolute assurance that abattoir procedures for producing DB can result, by themselves, in a commodity with a negligible risk of transmitting FMDV without complementary measures to reduce the likelihood of slaughtering infected cattle. The main areas of uncertainty are the amounts of residual FMDV-harbouring tissues within DB, and our understanding of what constitutes a safe level of contamination. More detailed guidance should be developed to specify the mitigating measures needed in support of the export of DB from regions that are not officially FMD-free. This will help to avoid differences in interpretation of what is needed that give rise to obstacles to trade.

Development and laboratory evaluation of a lateral flow device for the detection of swine vesicular disease virus in clinical samples

A lateral flow device (LFD) for the detection of swine vesicular disease (SVD) virus (SVDV) and differential diagnosis from foot-and-mouth disease (FMD) was developed using a monoclonal antibody (Mab C70). The performance of the LFD was evaluated in the laboratory on suspensions of vesicular epithelia and cell culture passage derived supernatants of SVDV and porcine teschovirus (enterovirus; PEV). The collection of test samples included 157 which were positive for SVDV (84 vesicular epithelial suspensions and 73 cell culture antigens) from suspected cases of vesicular disease in pigs collected from 14 countries between 1966 and 2008 and 663 samples which were either shown to be negative for SVDV and FMD virus (FMDV) or else collected from healthy pigs or demonstrated to be positive for FMDV, PEV or vesicular exanthema (VEV) and collected from 16 countries between 1965 and 2008 or else were derived from experimental animals. Three further samples containing vesicular stomatitis virus (VSV) were also tested. The diagnostic sensitivity of the LFD for SVDV was similar at 82% compared to 86% obtained by the reference method of antigen ELISA, and the diagnostic specificity was 100% compared to 99.7% for the ELISA. The device recognized virus strains of each of the known genotypes of the sole SVDV serotype. Reactions with FMDV, VEV, VSV and PEV which can produce clinically indistinguishable syndromes in pigs, did not occur. These data illustrate the potential for the LFD to be used next to the animal for providing rapid and objective support to veterinarians in their clinical judgment of vesicular disease in pigs and for the specific pen-side diagnosis of SVD and differential diagnosis from FMD.

Development of a real-time reverse transcription polymerase chain reaction assay for detection of marine caliciviruses (genus Vesivirus)

Marine caliciviruses form a distinct lineage within the genus Vesivirus (family Caliciviridae). This group includes vesicular exanthema of swine virus (VESV) and San Miguel sea lion virus (SMSV) and other related viruses which have been proposed to be marine in origin isolated from a variety of terrestrial and marine animals. Rapid and reliable detection of marine caliciviruses is important as these viruses appear to be widespread and can cause vesicular disease in a wide variety of susceptible hosts including pigs and experimentally infected cattle where clinical signs cannot be easily distinguished from foot-and-mouth disease (FMD), swine vesicular disease (SVD) and vesicular stomatitis (VS). A real-time RT-PCR assay targeting conserved nucleotide sequences in the RNA-dependent RNA polymerase (3D) region of the genome successfully detected cell culture-grown virus preparations of more than thirty marine calicivirus serotypes. Only the atypical SMSV serotypes 8 and 12 failed to be detected, which provided further indication of genetic divergence between these and the other calicivirus serotypes said to be marine in origin. The real-time RT-PCR assay also specifically amplified RNA from samples collected following experimental inoculation of pigs with VESV. No cross-reactivity was demonstrated when the assay was tested with RNA prepared from representative viruses of FMD, SVD and VS. The real-time RT-PCR assay described is a sensitive and specific tool for detection and differential diagnosis of these viruses from other vesicular-disease causing viruses.

‘Flames and fear on the farms’: controlling foot and mouth disease in Britain, 1892–2001*

Abstract For over a century, the British government has pursued a policy of national freedom from foot and mouth disease (F.M.D.), a highly contagious disease of cloven-footed animals. One of the cornerstones of this policy was the slaughter of infected animals. However, on several occasions – most notably in 2001 – slaughter struggled to contain F.M.D., and provoked widespread criticism and calls for policy change. Drawing upon a range of previously unexamined sources, this article examines the history of F.M.D. in Britain, in an attempt to explain the twenty-first-century persistence of a Victorian disease control policy.

Identification and isolation of foot-and-mouth disease virus from primary suspect cases in Korea in 2000.

The Republic of Korea had been free from foot and mouth disease (FMD) since 1934, until a recent outbreak in 2000. From March to April 2000, a total of 15 FMD outbreaks due to the serotype O virus were recorded. Coincidental outbreaks of FMD in cattle or pigs by the serotype O virus were reported in the region, including Taiwan, China, Japan, Russia and Mongolia. In this report, the results of emergency investigations of FMD cases on a dairy farm located approximately 5-km from the demilitarized zone in Korea are described. The causative agent of the disease was identified as the FMD virus O by reverse transcription-polymerase chain reaction (RT-PCR) assays using primers derived from the 3D polymerase, internal ribosome entry site (IRES), 1D/2B regions, enzyme-linked immunosorbent assay (ELISA) for antigen detection and typing. Sequence data of the partial 1D/2B region obtained from vesicular fluid showed close similarity (98% sequence identity) to the Kinmen isolate of the FMD virus O in Taiwan. The causative virus was isolated using black goat fetal lung cells following propagation in unweaned mice.

Recent outbreaks of foot and mouth disease in countries of east Asia.

Japan regained the status of freedom from foot and mouth disease (FMD) without vaccination in September 2000 and the Republic of Korea likewise obtained this status in September 2001. However, new outbreaks of FMD caused by the pan-Asian topotype have occurred in pigs in the Republic of Korea since May 2002. Taipei China has not experienced an outbreak of FMD since February 2001 and the country is currently implementing an eradication programme. These countries had been free from FMD for many decades when in 1997, the FMD virus (FMDV) once again invaded the region, particularly in 2000; this resulted in widespread occurrence of the disease. The types of FMDV were investigated by genome analysis, and in each case the virus concerned was found to be a member of the pan-Asian O lineage. The authors present the recent situations and the characteristics of FMD in countries of east Asia.

Emergence and re-emergence of vesicular stomatitis in the United States

Vesicular stomatitis (VS) is an important disease of cattle, horses and pigs. The causal agent is an arbovirus; vesicular stomatitis virus (VSV) of which two distinct serotypes New Jersey (NJ) and Indiana (IN) have been described. The clinical signs in cattle and pigs are undistinguishable from foot-and-mouth disease (FMD), one of the most devastating viral infections of livestock. VSV is the most important cause of vesicular disease in FMD-free countries in the Americas, causing thousands of outbreaks every year from southern Mexico to northern South America. In the United States VS has two different patterns of occurrence; in the southeastern states (Georgia, Alabama, North Carolina and South Carolina) a pattern of yearly occurrence of clinical cases in livestock was reported from early 1900s until the mid 1970s. Since then, viral activity in the region has been focal and limited to isolated wildlife populations. In contrast in the southwestern states (New Mexico, Arizona, Utah and Colorado) VS outbreaks have occurred sporadically at approximately 10-year intervals, with the last cycle of activity occurring from 1995 to 1998. Phylogenetic analyses of VSV have shown that distinct viral lineages occur in the southwestern and southeastern US. Furthermore, in the last 70 years each sporadic outbreak in the Southwest was associated to viral lineages distant from those causing previous outbreaks in the US but closely related to viruses maintained in endemic areas of Mexico. This pattern of viral occurrence contrasts with that observed in endemic areas in Central and South America where viral genetic lineages are maintained in specific ecological areas over long periods of time. The phylogenetic data together with the geographical and temporal distribution of outbreaks indicate that VSV does not have a stable endemic cycle in the western United States.

An immunoglobulin G based chimeric protein induced foot-and-mouth disease specific immune response in swine

Epitopes containing the residues 141aa–160aa and 200aa–213aa from foot-and-mouth disease (FMD) serotype O1K HK type FMDV VP1 were joined to a swine immunoglobulin G single heavy chain constant region (scIgG), creating a novel chimeric protein, named F1-scIgG. In this study, inoculation with F1-scIgG induced both FMD virus-neutralizing antibody response and T cell response in swine. Antisera from these F1-scIgG-inoculated swine protected suckling mice against 1000 lethal dose 50 (1000LD 50) FMD challenge. F1-scIgG-inoculated swine were also fully protected against 50LD 50 FMD virus challenge. The present study demonstrates the clear potential for viral epitopes linked with self-Ig in novel FMD vaccine design.

Managing an animal health emergency in Taipei China: foot and mouth disease.

Taipei China had been free from foot and mouth disease (FMD) over 68 years before the disease occurred in March 1997. The first suspected case was recorded on a pig farm in the Hsinchu Prefecture on 14 March 1997. Based on clinical signs, gross histopathological findings, and results of enzyme-linked immunosorbent assays and reverse-transcriptase polymerase chain reaction tests, diagnosis of FMD was confirmed by the Taiwan Animal Health Research Institute on 19 March 1997 and was reconfirmed by the FMD World Reference Laboratory in Pirbright (United Kingdom), on 25 March 1997. By the end of July 1997, 6,147 pig farms (about a quarter of the pig farms in Taipei China), were affected. The disease was well under control within two months by means of stamping-out and blanket vaccination. The Government purchased 21 million doses of inactivated oil-adjuvant FMD vaccine, which allowed for two injections per pig and one injection of other cloven-hoofed animals. Before the vaccine was used, the stamping-out policy was implemented, ensuring that all pigs in the affected farms were destroyed. After blanket vaccination, a partial stamping-out policy was adopted, i.e. only pigs showing clinical signs were destroyed.

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.

Risk assessment on the importation of milk and milk products (excluding cheese) from countries not free from foot and mouth disease

The authors discuss the risk assessment conducted by the Australian Quarantine and Inspection Service (AQIS) on the importation of milk and milk products (excluding cheese) from countries not free from foot and mouth disease (FMD). This assessment was undertaken in response to requests from countries wishing to export dairy products for sale on the Australian market. AQIS conducted a public consultation on the proposal, in line with Australian Government policy on transparency and accountability in the quarantine decision-making process. The authors examine the procedures involved in the investigation of the likely presence of FMD virus in milk of vaccinated and non-vaccinated cows, and of the heat treatment parameters effective in the inactivation of the virus. The data provide a useful aid in the assessment of the risk factors associated with the importation of milk and milk products, and in the development of quarantine conditions for importation.

Rapid detection of vesicular stomatitis virus New Jersey serotype in clinical samples by using polymerase chain reaction

Vesicular stomatitis virus of the New Jersey serotype (VSV-NJ) causes vesicular disease in cattle, pigs, and horses throughout the Americas. Vesicular disease is clinically indistinguishable from foot-and-mouth disease (FMD). Therefore, outbreaks of vesicular disease in FMD-free areas must be rapidly diagnosed by laboratory methods and affected farms must be quarantined until laboratory results confirm the absence of FMD. Diagnosis is currently performed in high-containment (biosafety level 3) laboratories by using complement fixation and virus isolation in tissue culture. We describe here an alternative method for the detection of VSV-NJ RNA in clinical samples. This method includes a rapid acid guanidine-phenol RNA extraction procedure coupled with a one-tube polymerase chain reaction (PCR) using reverse transcriptase. By using this test, we were able to detect the largest number of positive samples (53 of 58), followed by complement (48 of 58) and isolation in tissue culture (43 of 58). The primers chosen for this assay amplify a 642-nucleotide region of the phosphoprotein gene of VSV-NJ but not of VSV-IN. Sequencing of the PCR product enables genetic typing of virus isolates and epidemiological studies. Since no infectious materials are necessary to perform this test and any infectious virus in clinical samples is destroyed by acid guanidine-phenol treatment, diagnosis can be safely performed in regular diagnostic laboratories.