Caprine lentivirus in sheep milk and semen

Detection and isolation of small ruminant lentivirus in the amniotic fluid of goats

The objective of this study was to verify the presence of small ruminant lentivirus in the amniotic fluid of goats using molecular tests and viral isolation by cocultivation in the amniotic fluid of naturally infected goats. The study analyzed eight goats: seven were small ruminant lentivirus-positive and one was negative. The amniotic fluid was collected from each of the eight animals during cesarean section at 147 days of pregnancy. Cocultivation was undertaken using secondary goat nictitating membrane cell cultures obtained by explant from a small ruminant lentivirus-negative calf followed by trypsinization and sub-cultivation of the cells for 63 days. During this period, five supernatant collections were performed for DNA extraction and subsequent nested polymerase chain reaction. DNA was extracted from the amniotic fluid after 3 h of cellular sedimentation, from which a sample of 600 μL was taken from the sediment and another 600 μL sample from the supernatant. After DNA extraction, nested polymerase chain reaction was performed. Of the eight goats, 62.5 % (05/08) were small ruminant lentivirus-positive, with 43.75 % (07/16) of the total samples positive when considering the two repetitions (supernatant and cell sediment). Moreover, positivity was confirmed by small ruminant lentivirus pro-viral DNA amplification in the cell supernatant throughout the cocultivation period. Small ruminant lentivirus were present in the amniotic fluid samples from the naturally infected goats indicating an intrauterine transmission route. Moreover, this biological fluid can be adopted for the diagnosis of these lentiviruse because it is an important risk factor related to intrauterine transmission.

Vertical transmissibility of small ruminant lentivirus

This study aimed to evaluate by means of Nested Polymerase Chain Reaction (nPCR), co-cultivation and sequencing, with genetic comparison between strains (mother/newborn), the occurrence of vertical transmission of Small Ruminant Lentiviruses (SRLV) from naturally occurring nannies infected for their offspring. For the detection of SRLV seropositive progenitors, blood was collected from 42 nannies in the final third of gestation in tubes with and without anticoagulant. The diagnostic tests used were Western Blot (WB) and nPCR. During the period of birth, the same blood collection procedure was performed on 73 newborns at zero hours of birth, with the same diagnostic tests. Seventeen blood samples from seven-day-old kids, proven positive for SRLV by nPCR, chosen at random, were subjected to coculture in goat synovial membrane (GSM) cells for 105 days. The pro-viral DNA extracted from the cell supernatant from the coculture was subjected to nPCR. For DNA sequencing from the nPCR products, nine positive samples were chosen at random, four nannies with their respective offspring, also positive. Each sample was performed in triplicate, thus generating 27 nPCR products of which only 19 were suitable for analysis. Among the 42 pregnant goats, in 50% (21/42) pro-viral DNA was detected by nPCR, while in the WB, only 7.14% (3/42) presented antibodies against SRLV. Regarding neonates, of the 73 kids, 34 (46.57%) were positive for the virus, using the nPCR technique, while in the serological test (WB), three positive animals (4.10%) were observed. The coculture of the 17 samples with a positive result in the nPCR was confirmed in viral isolation by amplification of the SRLV pro-viral DNA. When aligned, the pro-viral DNA sequences (nannies and their respective offspring) presented homology in relation to the standard strain CAEV Co. It was concluded that the transmission of SRLV through intrauterine route was potentially the source of infection in the newborn goats.

Sheep infection by caprine lentivirus

SUMMARY The objective of this study was to demonstrate iatrogenic transmission of small ruminant lentivirus (SRLV) from goats to sheep and horizontal transmission between sheep. The study was conducted on a farm with separate goat and sheep rearing, and animals were monitored for lentivirus occurrence by clinical examination and testing by immunoblotting (IB), agar gel immunodiffusion (AGID), and nested polymerase chain reaction (nPCR). Positive results had not been observed in the sheep flock until this study. Conversely, virus positive dairy goats were known. For this reason, the farm performed the caprine arthritis-encephalitis (CAE) control program. The study was designed with a sheep group that presented positive animals for SRLV by nPCR. It was verified that three newborn animals in this group were rejected by their mothers and consequently received milk from the goat herd. These three animals remained with another 20 sheep of the same age, totaling 23 animals. After one year, during monitoring, 11 of the 23 animals in the group presented positive results in the nPCR and three demonstrated seroconversion by IB. Of the animals that had received goat milk, two had positive results in the nPCR and IB. The 11 animals positive in the nPCR were followed and it was verified that five animals did not present further positive results in the nPCR, nor seroconversion; two continued presenting positive results in the nPCR but were negative in the IB and AGID and four were positive in the nPCR, IB, and AGID. Thus, it was possible to demonstrate iatrogenic interspecific infection and the occurrence of horizontal caprine lentivirus transmission among sheep.

Evaluation of caprine arthritis-encephalitis virus transmission in newborn goat kids

ABSTRACT: Caprine arthritis encephalitis causes considerable losses in goat production. The main form of the caprine arthritis encephalitis virus transmission is through the ingestion of colostrum or milk from infected females. However, some transmissions cannot be explained in this manner. Therefore, this study aimed to evaluate transplacental transmission of caprine arthritis encephalitis virus. Blood samples were collected from 283 newborn kids of Anglo-Nubian and Saanen breeds born from seropositive and seronegative goats. Samples were collected immediately after birth and analyzed with agarose gel immunodiffusion and western blot. All samples were negative in the agarose gel immunodiffusion. However, the western blot test demonstrated that four kids were born positive for caprine arthritis encephalitis virus. This result indicates that although in a low frequency (1.4%), there is a possibility of transplacental transmission of small ruminant lentivirus.