West Nile Virus: Basic Principles, Replication Mechanism, Immune Response and Important Genetic Determinants of Virulence

Medical genetic

The splay leg syndrome in piglets: A review

Problem statement: The splay leg syndrome is the major congenital cause of lameness in suckling piglets. It is characterized by a temporarily impaired functionality of the hind leg muscles immediately after birth, resulting in an ability to stand and walk. Etiology and pathogenesis is complex and remain still poorly understood. Approach: The aim of the present study is to perform the update information about the etiology, clinical signs and control strategies of the syndrome. Results: A sexaffected inheritance of the splay leg syndrome is assumed since higher frequencies have been observed in male piglets. Several biochemical and histomorphological investigations indicate an immaturity of the skeletal muscle in the affected piglets at birth. Splay leg is caused by a reduction of the axonal diameter and myelin sheath thickness of the fiber that innervate the hindlimb adductors. The existence of one or more major genes for congenital splay leg seems possible. Among the fragments strongly displayed in the splay leg muscle, are identified the porcine CDKN3 gene. Various management and genetic factors have been connected with the etiology, such as the farrowing induction, low birth weight, short gestation lengths, slippery floors and breeds (e.g., Large White and Landrace). Moreover, nutrition can play a role to pathogenesis, as choline or methionine deficiency in sow diets and the fusarium toxicity. Furthermore, Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) are also involved in etiological factors. Piglets suffering from splay leg should be kept in a warm place and be helped to take colostrums or artificial milk for 2-3 days. Conclusion: Management practices should be applied in order to be avoided the occurrence of splay leg syndrome, such as non-slip floors, use of anti-mycotoxins products in feed, avoiding the farrowing induction before day 113. Finally, a herd health management programme should be applied in order to prevent and control PRRSV infection. © 2012 Science Publications

Exploration of the Connection Between Porcine Necrotic Ear Syndrome and PCV2 Infection

This study provides an overview of current knowledge relating to porcine necrotic ear syndrome (or ear tip necrosis) associated with PCV2 infection. It is believed that Porcine Circovirus type 2 (PCV2) may be involved in etiology of porcine necrotic ear syndrome. PCV2 is the primary causative agent for Porcine Circovirus Associated Diseases (PCVAD). In cases when clinical signs of PCVAD (mainly PMWS) are present on a farm, the porcine necrotic ear syndrome is more often. Initially, the lesions of ear tip necrosis appeared at the margin of the pinna(e) as asuperficial vesicular dermatitis associated with superficial auricular trauma. These lesions are characterized by systemic necrotizing vasculitis accompanied by epidermal necrosis/ulceration and dermal haemorrhage. The purpose of this study is to investigate the connection between clinical signs of porcine necrotic ear syndrome and of PCV2

Porcine respiratory and reproductive syndrome virus vaccinology: A review for commercial vaccines

Porcine Reproductive and Respiratory Syndrome (PRRS) since its appearance in Europe in the early 1990's has resulted in tremendous economic losses. Under field conditions vaccination is one of the most efficient strategies for the prevention and control of PRRS. The aim of this study is to perform the PRRSV vaccinology regarding current status of commercial vaccines in Europe. There are two types of PRRSV commercial available vaccines in Europe: Killed Virus (KV) or inactivated vaccines and Modified-Live Virus (MLV) or attenuated vaccines. EU KV commercial vaccines provide limited efficacy due to the weak stimulation of the immune system and no effective induction of neutralizing antibodies. However, KV vaccines can induce a strong Cell Mediated Immune (CMI) response. One the other hand, commercial EU MLV vaccines provide effective strain-specific protection, only partial protection against genetically heterologous PRRSV and elicit relatively late humoral and CMI responses which lead to delayed protection. In Europe, the KV vaccination prove to reduce the negative effects of PRRSV in breeding herds, improving their reproductive performance, e.g., increase of farrowing rate and number of live or weaned pigs, reduction of premature farrowing rate, abortion rate and number of mummified and stillborn piglets. The use of commercial MLV vaccines in PRRSV-infected breeding herds leads to improvement of: (a) reproductive performance e.g., reduction of the abortion and return to oestrus rate and increase of the farrowing rate and number of weaners, (b) the viraemic status, morbidity and mortality rate of piglets and (c) the growth performance of vaccinated pigs. In conclusion, nowadays the use of MLV or KV vaccines in Europe is the most economical tool to control the economic losses of PRRSV infection. However, the development of more efficacious PRRSV vaccines is the significant future goal for PRRSV vaccinology. © 2012 Science Publication