Foot-and-mouth disease (FMD) is an economically important contagious disease of livestock mainly cattle, buffalo, sheep, goats, and pig. There is limited data available on pathogenesis of foot and ...mouth disease in goats. In the study, the sheep and goats were infected experimentally with a serotype O foot-and-mouth disease virus by different challenge routes. The sheep and goats challenged by coronary band route and coronary band and intra-dermo-lingual route exhibited FMD clinical signs at 2–5 days post challenge. Whereas intra-dermo-lingual challenged sheep and goats did not exhibit FMD clinical signs. Live virus could be isolated from blood of infected sheep and goats at 2–5 days post challenge. Viral RNA could be detected from blood of infected sheep and goats at 1–10 days post challenge. The neutralizing antibody titre was detected at 10 days post challenge and maintained up to 35 days post challenge in all infected sheep and goats. Non structural protein (NSP) antibodies were detected as early as 5–10 days post challenge and remain positive up to 35 days post challenge in the infected sheep and goats. In conclusion, the pathogenesis of sheep and goats with serotype O foot and mouth disease virus by different challenge routes could be demonstrated.
Foot-and-mouth disease virus (FMDV) samples transported to the laboratory from far and inaccessible areas for serodiagnosis pose a major problem in a tropical country like India, where there is ...maximum temperature fluctuation. Inadequate storage methods lead to spoilage of FMDV samples collected from clinically positive animals in the field. Such samples are declared as non-typeable by the typing laboratories with the consequent loss of valuable epidemiological data. The present study evaluated the usefulness of FTA
® Classic Cards for the collection, shipment, storage and identification of the FMDV genome by RT-PCR and real-time RT-PCR. The stability of the viral RNA, the absence of infectivity and ease of processing the sample for molecular methods make the FTA
® cards a useful option for transport of FMDV genome for identification and serotyping. The method can be used routinely for FMDV research as it is economical and the cards can be transported easily in envelopes by regular document transport methods. Live virus cannot be isolated from samples collected in FTA
® cards, which is a limitation. This property can be viewed as an advantage as it limits the risk of transmission of live virus.
Sudden death of ducklings was reported in a duck farm located at Tiruvallur district in Tamil Nadu, India. Disease investigation began with post mortem findings of dead birds revealing enlarged ...pale-pink / pale-yellow liver with multifocal petechiae and ecchymosis. A positive amplification with duck hepatitis A virus specific primers by reverse transcription-polymerase chain reaction (RT-PCR) on the tissue samples collected from dead birds indicated infection by duck hepatitis A virus (DHAV), an avian picornavirus, known to cause acute and high-mortality in ducklings. The virus isolation was successful in 9-days old embryonated chicken eggs, in primary chicken embryo fibroblast (CEF) cells and from experimentally infected ducklings. The embryonic death on day 5 to 7 post inoculation in chicken embryos with signs of cutaneous hemorrhage, edema and greenish yellow liver together with histopathology of embryonic liver and kidney further confirmed DHAV infection. TEM analysis of the infected allantoic fluid and infected CEF cell culture supernatant showed the presence of spherical shaped, non-enveloped virion particles of ~ 20–38 nm diameter, typical for DHAV. Experimental infection of ducklings with RT-PCR positive tissue supernatant caused 40% to 50% mortality with typical petechial hemorrhages on the surface of liver. Further, histopathological analysis and RT-PCR of the inoculated duckling’s tissues confirmed the presence of DHAV. Nucleotide sequencing of the 5′UTR region and VP1 region confirmed duck hepatitis A virus genotype 2 (DHAV-2). To the best of our knowledge, this is the first report of laboratory confirmation of DHAV-2 in India. This study warrants the need for the extensive epidemiological surveillance to understand the prevalence of DHAV-2 in India and to take appropriate control measures to curtail the disease spread.
Serology is used to predict vaccine induced protection against challenge with a heterologous strain of the same serotype of foot-and-mouth disease virus (FMDV). To evaluate the accuracy of such ...predictions, we compared the protection afforded to cattle vaccinated with the O
1 Manisa strain of FMDV against challenge with either a homologous (O
1 Manisa) or a heterologous strain (O
1 Campos). Serology by virus neutralization test (VNT) using O
1 Manisa antiserum predicted an acceptable protection against such a challenge. Two experiments were carried out to compare the results for consistency. A total of 78 naïve cattle were vaccinated with different antigen payloads (60–0.94
μg) of O
1 Manisa. They were challenged by intradermolingual inoculation with live FMDV, either O
1 Manisa or O
1 Campos. Unvaccinated naïve control cattle (
n
=
20) were also challenged with either the O
1 Manisa or O
1 Campos viruses and all developed generalized FMD. The protection results for the vaccinated cattle revealed that higher payloads of O
1 Manisa vaccine were needed to protect against heterologous challenge compared to that for homologous challenge. The 50% protective dose (PD
50) values for the vaccine in experiments 1 and 2 were found to be 28.78 and 9.44 for the homologous challenge and 3.98 and 5.01 for heterologous challenge. Furthermore, protection against O
1 Campos required a higher level of vaccine-induced antibody against this virus compared to the level of O
1 Manisa neutralizing antibody associated with protection against homologous challenge. The 50% protective level of
in vitro neutralizing antibody was found to be log
10
1.827 for O
1 Campos and log
10
0.954 for O
1 Manisa based on O
1 Manisa based virus neutralization test.
Abstract Serology is used to predict vaccine induced protection against challenge with a heterologous strain of the same serotype of foot-and-mouth disease virus (FMDV). To evaluate the accuracy of ...such predictions, we compared the protection afforded to cattle vaccinated with the O1 Manisa strain of FMDV against challenge with either a homologous (O1 Manisa) or a heterologous strain (O1 Campos). Serology by virus neutralization test (VNT) using O1 Manisa antiserum predicted an acceptable protection against such a challenge. Two experiments were carried out to compare the results for consistency. A total of 78 naïve cattle were vaccinated with different antigen payloads (60–0.94 μg) of O1 Manisa. They were challenged by intradermolingual inoculation with live FMDV, either O1 Manisa or O1 Campos. Unvaccinated naïve control cattle ( n = 20) were also challenged with either the O1 Manisa or O1 Campos viruses and all developed generalized FMD. The protection results for the vaccinated cattle revealed that higher payloads of O1 Manisa vaccine were needed to protect against heterologous challenge compared to that for homologous challenge. The 50% protective dose (PD50 ) values for the vaccine in experiments 1 and 2 were found to be 28.78 and 9.44 for the homologous challenge and 3.98 and 5.01 for heterologous challenge. Furthermore, protection against O1 Campos required a higher level of vaccine-induced antibody against this virus compared to the level of O1 Manisa neutralizing antibody associated with protection against homologous challenge. The 50% protective level of in vitro neutralizing antibody was found to be log10 1.827 for O1 Campos and log10 0.954 for O1 Manisa based on O1 Manisa based virus neutralization test.
Bovine tropical theileriosis (BTT) is a tick-borne protozoan disease of cattle and responsible for major economic losses to the dairy farmers in India. This report describes diagnosis, genotyping and ...successful treatment of heavy infection of Theileria annulata in an organized dairy farm at Kattupakkam, Chennai. Four cross bred cows of 2 to 5 years of age showed clinical signs i.e., anorexia, salivation and panting. Clinical examination revealed pyrexia (40.0 °C to 40.1 °C), pale mucus membranes, enlarged prescapular lymph nodes and haemoglobinuria. The peripheral blood smear examination of infected cows revealed presence of piroplasm within the RBCs indicating high parasitemia. Haematology results suggested that decreased levels of Hb, RBC, WBC and PCV in the infected cows when compared with normal reference values. There were increased serum ALT and AST values and reduced serum total protein, albumin, calcium and phosphorous values in the infected cows. Semi-nested PCR using T. annulata specific oligonucleotide primers amplified 199 bp of the partial T. annulata 18S rRNA gene. Presence of four satellite markers TS6, TS8, TS9, and TS12 in the Theileria annulata isolates 1 and 2 indicating that the isolates were the same haplotype and suggested the infection in the farm was due to a single haplotype of T. annulata parasite. Based on the clinical signs, microscopic examination of blood smear and molecular diagnosis, the condition was diagnosed as tropical theileriosis. Infected cows were successfully treated with a single deep intramuscular injection of buparvaquone (Zubion®, INTAS pharmaceuticals LTD, Ahmedabad, India) along with supportive medication.
In this study, the nucleotide sequences of the complete leader proteinase (Lpro) region of 21 isolates of foot-and-mouth disease virus (FMDV) serotype O collected during various outbreaks in India ...were sequenced and compared with vaccine strains. The phylogenetic analysis of these Lpro sequences showed a difference in the clustering of the isolates based on the VP1 capsid coding region sequences. The comparison of amino acid sequences at the N terminus end of the Lpro region showed very high variability, although 2 conserved start codons (AUG) at 1st and 29th sites. Furthermore, all the amino acid residues that formed the active cleft site of the Lpro sequences of this study were conserved. These results suggest that Lpro sequences could also be used for phylogenetic comparison of FMDV isolates.
The ability of foot-and-mouth disease (FMD) vaccine to protect sheep and goats from a homologous direct in-contact challenge and the effect on virus excretion from the nasal secretions and oropharynx ...was examined. An experimental oil adjuvant O₁ Manisa FMD vaccine protected sheep and goats from clinical disease from 7 days post vaccination following 24 hours of direct in-contact exposure to four infected donor sheep or goats. Goats required lower antibody titres for protection when compared with sheep. Protection from clinical disease did not prevent localized viral replication in goats and at least two goats had viral RNA detected on day 28 post challenge. Quantitative reverse transcriptase polymerase chain reaction showed that the level of virus replication shortly after direct in-contact challenge in oropharynx and nasal secretions of vaccinated animals was reduced by 100 and 1000 times respectively when compared with unvaccinated controls. The findings also show that after direct in-contact challenge, use of FMD vaccine will prevent or reduce local virus replication, thereby significantly reduce the amount of virus released into the environment in the all-important early post-exposure period. There is low risk of vaccinated animals transmitting disease as live virus could not be readily isolated.
Emergence of genetically and antigenically divergent lineages/genotypes and poor intergenotypic antigenic coverage is a major concern in serotype A foot-and-mouth-disease virus (FMDV) in India. In ...2009, to cover antigenic diversity emerged in serotype A virus field isolates, IND40/2000 was selected as the new vaccine strain for incorporation in the trivalent FMD vaccine formulation used in India. Although current vaccine strain (IND40/2000) covers most isolates antigenically, a few VP359-deletion group isolates showed low r-value in routine vaccine matching exercise. The VP359-deletion group within genotype 18 emerged first in late part of 2002 and in 2007 causing outbreaks along with non-deletion isolates of the same genotype. In case of emergence or re-emergence of more antigenically divergent isolates in future, a need for a new vaccine candidate to cover maximum isolates of both deletion and non-deletion group may arise. Four alternate candidate vaccine strains (IND281/2003, IND195/2007, IND360/2007 and IND123/2008) were selected based on set criteria and antigenic relationships with field isolates sampled between 2002 and 2009 were analyzed using a micro-neutralization test. Phylogenetic analysis based on capsid region of serotype A isolates revealed existence of two broad distinct clusters (VP359-deletion and non-deletion group) within genotype 18. The VP359-deletion group has diversified genetically with time giving rise to three different sub-lineages (clade18a, 18b and 18c). The present study indicates that the virus candidates IND281/2003 (VP359-deletion group) and IND195/2007 (non-deletion group) can be used as an adjunct or alternative strain to currently used vaccine strain IND40/2000 in case of emergence of more antigenically divergent isolates in future.
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