Research on Porcine Circovirus
Porcine circovirus (PCV) belongs to the Circoviridae family and is a circular single-stranded DNA virus. Porcine circoviruses currently include porcine circovirus type 1 (PCV1), porcine circovirus type 2 (PCV2) and porcine circovirus type 3 (PCV3). Among them, PCV2 has caused severe economic losses to the pig industry. Recent studies have found that in some cases of porcine dermatitis and nephropathy syndrome (PDNS) and reproductive failure (RF), PCV2 was not detected by real-time polymerase chain reaction methods. However, through histopathology and molecular biological diagnostic technology, a new type of porcine circovirus was detected, which was named as PCV3. PCV3 was first discovered in 2015 through genetic sequencing analysis in tissues suffering from PDNS, reproductive failure, myocarditis and multisystem inflammation. The virus is the third member of the genus circovirus.
To end Classical Swine Fever (CSF) vaccination-
The surveillance and analysis of neutralizing antibodies against CSF in sentinel pigs.
Classical swine fever (CSF) is a highly contagious viral disease that affects domestic and wild pigs. Due to the significant global economic impact on countries experiencing outbreaks, the disease is notifiable to the World Organization for Animal Health (WOAH). Because of the comprehensive vaccination strategy, there have been no confirmed cases of CSF since 2006 in Taiwan. Council of Taiwan prepare to end vaccinations against CSF, and initiated a surveillance program since 2021. One of the national CSF surveillances of domestic pigs is the “sentinel pig program”. Each year, over 300 domestic pig farms were sampled from sentinel pigs that have not received CSF vaccination. These pigs were sampled twice, with the first inspection conducted when the pigs were 3-12 week-old and the second inspection at 13-27 week-old. The specimens were tested for CSFV RNA and anti-CSFV neutralizing antibody (NA). In this report, we presented that the seropositive rates for anti-CSFV NAs during the first inspection of sentinel pigs were 68% in 2021 and 70.8% in 2022. During the second inspection, the seropositive rates for anti-CSFV NAs significantly decreased to 10.8% in 2021 and 9.5% in 2022. To confirm whether CSFV exist in the environment, antibody levels and other surveillance measures should be continuously monitored even as all farms gradually stop CSFV vaccination.
The report of “East Asia CVO/contact persons meeting on Peste des Petits Ruminants & Lumpy Skin Disease”
This meeting aims to share the disease status, distribution and control measures of Peste des Petits Ruminants (PPR) and Lumpy Skin Disease (LSD) of the participating members, and under global and regional context. This meeting also aims to strengthen the cooperation and connection between the diagnostic labs, in the hope to enforce the prevention and control of PPR and LSD. For PPR, regional disease status, and also “PPR global control and eradication strategy (GCES)” and its progress, were introduced. For LSD, latest revisions of WOAH territorial manual were covered, especially focusing on the phylogenetic status of vaccine-like recombinant strains that emerged in South-East Asia recently. The influence of these recombinant strains to the diagnostic tests were discussed, and the choice of safe and efficacious vaccine were emphasized.
Conclusions and recommendations: Participating the international meeting like this can facilitate information sharing of diseases status and control measures between neighboring countries, and help to focus the resources in diseases of high priority. According to experts, under natural condition, the mutation rate of LSDV is slow, and evidences shown that the emergence of the recombinant strains was due to poor quality control of vaccine production; therefor continue monitoring was needed. LSDV is a popular research subject, topics such as its mutation mechanism, virulence gene, nature hosts, diagnostic techniques, risk factors, etc., warrant future researches.